From 64de3c12533145c97ce2ffcefaf3c291caaa204c Mon Sep 17 00:00:00 2001
From: Jaime Soriano Pastor <jaime.soriano@elastic.co>
Date: Wed, 18 Sep 2019 18:26:57 +0200
Subject: [PATCH] Implement check and add headers in mage (#13215)

Add a framework to wrap go tooling in mage, taken from go-txtfile.

Using it, reimplement all uses of go-licenser in mage.

go-licenser is vendored.
---
 Makefile                                      |  12 +-
 NOTICE.txt                                    |  16 ++
 dev-tools/mage/check.go                       |  21 ++
 dev-tools/mage/fmt.go                         |  12 +-
 dev-tools/mage/gotool/get.go                  |  31 +++
 dev-tools/mage/gotool/go.go                   | 257 ++++++++++++++++++
 dev-tools/mage/gotool/licenser.go             |  37 +++
 dev-tools/mage/install.go                     |  49 ++++
 dev-tools/mage/target/common/check.go         |   5 +
 dev-tools/mage/target/common/fmt.go           |   5 +
 libbeat/scripts/Makefile                      |  10 +-
 magefile.go                                   |  51 +++-
 .../elastic/go-licenser/CONTRIBUTING.md       |  47 ++++
 vendor/github.com/elastic/go-licenser/LICENSE | 202 ++++++++++++++
 .../github.com/elastic/go-licenser/Makefile   | 105 +++++++
 vendor/github.com/elastic/go-licenser/NOTICE  |   5 +
 .../github.com/elastic/go-licenser/README.md  |  46 ++++
 .../elastic/go-licenser/appveyor.yml          |  38 +++
 .../github.com/elastic/go-licenser/error.go   |  39 +++
 vendor/github.com/elastic/go-licenser/go.mod  |   1 +
 .../elastic/go-licenser/licensing/doc.go      |  20 ++
 .../elastic/go-licenser/licensing/license.go  | 132 +++++++++
 vendor/github.com/elastic/go-licenser/main.go | 236 ++++++++++++++++
 vendor/github.com/elastic/go-licenser/path.go |  54 ++++
 .../github.com/elastic/go-licenser/version.go |  23 ++
 vendor/vendor.json                            |  16 ++
 26 files changed, 1440 insertions(+), 30 deletions(-)
 create mode 100644 dev-tools/mage/gotool/get.go
 create mode 100644 dev-tools/mage/gotool/go.go
 create mode 100644 dev-tools/mage/gotool/licenser.go
 create mode 100644 dev-tools/mage/install.go
 create mode 100644 vendor/github.com/elastic/go-licenser/CONTRIBUTING.md
 create mode 100644 vendor/github.com/elastic/go-licenser/LICENSE
 create mode 100644 vendor/github.com/elastic/go-licenser/Makefile
 create mode 100644 vendor/github.com/elastic/go-licenser/NOTICE
 create mode 100644 vendor/github.com/elastic/go-licenser/README.md
 create mode 100644 vendor/github.com/elastic/go-licenser/appveyor.yml
 create mode 100644 vendor/github.com/elastic/go-licenser/error.go
 create mode 100644 vendor/github.com/elastic/go-licenser/go.mod
 create mode 100644 vendor/github.com/elastic/go-licenser/licensing/doc.go
 create mode 100644 vendor/github.com/elastic/go-licenser/licensing/license.go
 create mode 100644 vendor/github.com/elastic/go-licenser/main.go
 create mode 100644 vendor/github.com/elastic/go-licenser/path.go
 create mode 100644 vendor/github.com/elastic/go-licenser/version.go

diff --git a/Makefile b/Makefile
index 16f326ab0200..a75c772d7aa6 100644
--- a/Makefile
+++ b/Makefile
@@ -98,16 +98,12 @@ check: python-env
 	@git diff-index --exit-code HEAD --
 
 .PHONY: check-headers
-check-headers:
-	@go get -u github.com/elastic/go-licenser
-	@go-licenser -d -exclude x-pack -exclude generator/beat/\{beat\} -exclude generator/metricbeat/\{beat\}
-	@go-licenser -d -license Elastic x-pack
+check-headers: mage
+	@mage checkLicenseHeaders
 
 .PHONY: add-headers
-add-headers:
-	@go get github.com/elastic/go-licenser
-	@go-licenser -exclude x-pack
-	@go-licenser -license Elastic x-pack
+add-headers: mage
+	@mage addLicenseHeaders
 
 # Corrects spelling errors
 .PHONY: misspell
diff --git a/NOTICE.txt b/NOTICE.txt
index 907b79cf3b35..da031af8026c 100644
--- a/NOTICE.txt
+++ b/NOTICE.txt
@@ -859,6 +859,22 @@ License type (autodetected): Apache-2.0
 Apache License 2.0
 
 
+--------------------------------------------------------------------
+Dependency: github.com/elastic/go-licenser
+Version: 0.2.0
+Revision: 2b2abd4ee9b58025ebd0630d7621cfd7619f58ac
+License type (autodetected): Apache-2.0
+./vendor/github.com/elastic/go-licenser/LICENSE:
+--------------------------------------------------------------------
+Apache License 2.0
+
+-------NOTICE-----
+Elastic go-licenser
+Copyright 2018 Elasticsearch B.V.
+
+This product includes software developed at
+Elasticsearch, B.V. (https://www.elastic.co/).
+
 --------------------------------------------------------------------
 Dependency: github.com/elastic/go-lookslike
 Version: =v0.3.0
diff --git a/dev-tools/mage/check.go b/dev-tools/mage/check.go
index 86f0a28ef617..6c30bd1dafc1 100644
--- a/dev-tools/mage/check.go
+++ b/dev-tools/mage/check.go
@@ -35,6 +35,7 @@ import (
 	"github.com/magefile/mage/sh"
 	"github.com/pkg/errors"
 
+	"github.com/elastic/beats/dev-tools/mage/gotool"
 	"github.com/elastic/beats/libbeat/processors/dissect"
 )
 
@@ -189,6 +190,26 @@ func GoVet() error {
 	return errors.Wrap(err, "failed running go vet, please fix the issues reported")
 }
 
+// CheckLicenseHeaders checks license headers in .go files.
+func CheckLicenseHeaders() error {
+	fmt.Println(">> fmt - go-licenser: Checking for missing headers")
+
+	mg.Deps(InstallGoLicenser)
+
+	var license string
+	switch BeatLicense {
+	case "ASL2", "ASL 2.0":
+		license = "ASL2"
+	case "Elastic", "Elastic License":
+		license = "Elastic"
+	default:
+		return errors.Errorf("unknown license type %v", BeatLicense)
+	}
+
+	licenser := gotool.Licenser
+	return licenser(licenser.Check(), licenser.License(license))
+}
+
 // CheckDashboardsFormat checks the format of dashboards
 func CheckDashboardsFormat() error {
 	dashboardSubDir := "/_meta/kibana/"
diff --git a/dev-tools/mage/fmt.go b/dev-tools/mage/fmt.go
index e2671015fa98..8851f67676ad 100644
--- a/dev-tools/mage/fmt.go
+++ b/dev-tools/mage/fmt.go
@@ -26,6 +26,8 @@ import (
 	"github.com/magefile/mage/mg"
 	"github.com/magefile/mage/sh"
 	"github.com/pkg/errors"
+
+	"github.com/elastic/beats/dev-tools/mage/gotool"
 )
 
 var (
@@ -35,9 +37,6 @@ var (
 	// GoImportsLocalPrefix is a string prefix matching imports that should be
 	// grouped after third-party packages.
 	GoImportsLocalPrefix = "github.com/elastic"
-
-	// GoLicenserImportPath controls the import path used to install go-licenser.
-	GoLicenserImportPath = "github.com/elastic/go-licenser"
 )
 
 // Format adds license headers, formats .go files with goimports, and formats
@@ -120,9 +119,7 @@ func AddLicenseHeaders() error {
 
 	fmt.Println(">> fmt - go-licenser: Adding missing headers")
 
-	if err := sh.Run("go", "get", GoLicenserImportPath); err != nil {
-		return err
-	}
+	mg.Deps(InstallGoLicenser)
 
 	var license string
 	switch BeatLicense {
@@ -134,5 +131,6 @@ func AddLicenseHeaders() error {
 		return errors.Errorf("unknown license type %v", BeatLicense)
 	}
 
-	return sh.RunV("go-licenser", "-license", license)
+	licenser := gotool.Licenser
+	return licenser(licenser.License(license))
 }
diff --git a/dev-tools/mage/gotool/get.go b/dev-tools/mage/gotool/get.go
new file mode 100644
index 000000000000..6a147ca93921
--- /dev/null
+++ b/dev-tools/mage/gotool/get.go
@@ -0,0 +1,31 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package gotool
+
+type goGet func(opts ...ArgOpt) error
+
+// Get runs `go get` and provides optionals for adding command line arguments.
+var Get goGet = runGoGet
+
+func runGoGet(opts ...ArgOpt) error {
+	args := buildArgs(opts)
+	return runVGo("get", args)
+}
+
+func (goGet) Update() ArgOpt            { return flagBoolIf("-u", true) }
+func (goGet) Package(pkg string) ArgOpt { return posArg(pkg) }
diff --git a/dev-tools/mage/gotool/go.go b/dev-tools/mage/gotool/go.go
new file mode 100644
index 000000000000..def2d5d59acb
--- /dev/null
+++ b/dev-tools/mage/gotool/go.go
@@ -0,0 +1,257 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package gotool
+
+import (
+	"os"
+	"strings"
+
+	"github.com/magefile/mage/mg"
+	"github.com/magefile/mage/sh"
+)
+
+// Args holds parameters, environment variables and flag information used to
+// pass to the go tool.
+type Args struct {
+	extra map[string]string // extra flags one can pass to the command
+	env   map[string]string
+	flags map[string][]string
+	pos   []string
+}
+
+// ArgOpt is a functional option adding info to Args once executed.
+type ArgOpt func(args *Args)
+
+type goTest func(opts ...ArgOpt) error
+
+// Test runs `go test` and provides optionals for adding command line arguments.
+var Test goTest = runGoTest
+
+// ListProjectPackages lists all packages in the current project
+func ListProjectPackages() ([]string, error) {
+	return ListPackages("./...")
+}
+
+// ListPackages calls `go list` for every package spec given.
+func ListPackages(pkgs ...string) ([]string, error) {
+	return getLines(callGo(nil, "list", pkgs...))
+}
+
+// ListTestFiles lists all go and cgo test files available in a package.
+func ListTestFiles(pkg string) ([]string, error) {
+	const tmpl = `{{ range .TestGoFiles }}{{ printf "%s\n" . }}{{ end }}` +
+		`{{ range .XTestGoFiles }}{{ printf "%s\n" . }}{{ end }}`
+
+	return getLines(callGo(nil, "list", "-f", tmpl, pkg))
+}
+
+// HasTests returns true if the given package contains test files.
+func HasTests(pkg string) (bool, error) {
+	files, err := ListTestFiles(pkg)
+	if err != nil {
+		return false, err
+	}
+	return len(files) > 0, nil
+}
+
+func (goTest) WithCoverage(to string) ArgOpt {
+	return combine(flagArg("-cover", ""), flagArgIf("-test.coverprofile", to))
+}
+func (goTest) Short(b bool) ArgOpt        { return flagBoolIf("-test.short", b) }
+func (goTest) Use(bin string) ArgOpt      { return extraArgIf("use", bin) }
+func (goTest) OS(os string) ArgOpt        { return envArgIf("GOOS", os) }
+func (goTest) ARCH(arch string) ArgOpt    { return envArgIf("GOARCH", arch) }
+func (goTest) Create() ArgOpt             { return flagArg("-c", "") }
+func (goTest) Out(path string) ArgOpt     { return flagArg("-o", path) }
+func (goTest) Package(path string) ArgOpt { return posArg(path) }
+func (goTest) Verbose() ArgOpt            { return flagArg("-test.v", "") }
+func runGoTest(opts ...ArgOpt) error {
+	args := buildArgs(opts)
+	if bin := args.Val("use"); bin != "" {
+		flags := map[string][]string{}
+		for k, v := range args.flags {
+			if strings.HasPrefix(k, "-test.") {
+				flags[k] = v
+			}
+		}
+
+		useArgs := &Args{}
+		*useArgs = *args
+		useArgs.flags = flags
+
+		_, err := sh.Exec(useArgs.env, os.Stdout, os.Stderr, bin, useArgs.build()...)
+		return err
+	}
+
+	return runVGo("test", args)
+}
+
+func getLines(out string, err error) ([]string, error) {
+	if err != nil {
+		return nil, err
+	}
+
+	lines := strings.Split(out, "\n")
+	res := lines[:0]
+	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if len(line) > 0 {
+			res = append(res, line)
+		}
+	}
+
+	return res, nil
+}
+
+func callGo(env map[string]string, cmd string, opts ...string) (string, error) {
+	args := []string{cmd}
+	args = append(args, opts...)
+	return sh.OutputWith(env, mg.GoCmd(), args...)
+}
+
+func runVGo(cmd string, args *Args) error {
+	return execGoWith(func(env map[string]string, cmd string, args ...string) error {
+		_, err := sh.Exec(env, os.Stdout, os.Stderr, cmd, args...)
+		return err
+	}, cmd, args)
+}
+
+func runGo(cmd string, args *Args) error {
+	return execGoWith(sh.RunWith, cmd, args)
+}
+
+func execGoWith(
+	fn func(map[string]string, string, ...string) error,
+	cmd string, args *Args,
+) error {
+	cliArgs := []string{cmd}
+	cliArgs = append(cliArgs, args.build()...)
+	return fn(args.env, mg.GoCmd(), cliArgs...)
+}
+
+func posArg(value string) ArgOpt {
+	return func(a *Args) { a.Add(value) }
+}
+
+func extraArg(k, v string) ArgOpt {
+	return func(a *Args) { a.Extra(k, v) }
+}
+
+func extraArgIf(k, v string) ArgOpt {
+	if v == "" {
+		return nil
+	}
+	return extraArg(k, v)
+}
+
+func envArg(k, v string) ArgOpt {
+	return func(a *Args) { a.Env(k, v) }
+}
+
+func envArgIf(k, v string) ArgOpt {
+	if v == "" {
+		return nil
+	}
+	return envArg(k, v)
+}
+
+func flagArg(flag, value string) ArgOpt {
+	return func(a *Args) { a.Flag(flag, value) }
+}
+
+func flagArgIf(flag, value string) ArgOpt {
+	if value == "" {
+		return nil
+	}
+	return flagArg(flag, value)
+}
+
+func flagBoolIf(flag string, b bool) ArgOpt {
+	if b {
+		return flagArg(flag, "")
+	}
+	return nil
+}
+
+func combine(opts ...ArgOpt) ArgOpt {
+	return func(a *Args) {
+		for _, opt := range opts {
+			if opt != nil {
+				opt(a)
+			}
+		}
+	}
+}
+
+func buildArgs(opts []ArgOpt) *Args {
+	a := &Args{}
+	combine(opts...)(a)
+	return a
+}
+
+// Extra sets a special k/v pair to be interpreted by the execution function.
+func (a *Args) Extra(k, v string) {
+	if a.extra == nil {
+		a.extra = map[string]string{}
+	}
+	a.extra[k] = v
+}
+
+// Val returns a special functions value for a given key.
+func (a *Args) Val(k string) string {
+	if a.extra == nil {
+		return ""
+	}
+	return a.extra[k]
+}
+
+// Env sets an environmant variable to be passed to the child process on exec.
+func (a *Args) Env(k, v string) {
+	if a.env == nil {
+		a.env = map[string]string{}
+	}
+	a.env[k] = v
+}
+
+// Flag adds a flag to be passed to the child process on exec.
+func (a *Args) Flag(flag, value string) {
+	if a.flags == nil {
+		a.flags = map[string][]string{}
+	}
+	a.flags[flag] = append(a.flags[flag], value)
+}
+
+// Add adds a positional argument to be passed to the child process on exec.
+func (a *Args) Add(p string) {
+	a.pos = append(a.pos, p)
+}
+
+func (a *Args) build() []string {
+	args := make([]string, 0, 2*len(a.flags)+len(a.pos))
+	for k, values := range a.flags {
+		for _, v := range values {
+			args = append(args, k)
+			if v != "" {
+				args = append(args, v)
+			}
+		}
+	}
+
+	args = append(args, a.pos...)
+	return args
+}
diff --git a/dev-tools/mage/gotool/licenser.go b/dev-tools/mage/gotool/licenser.go
new file mode 100644
index 000000000000..1d7c6d5255c7
--- /dev/null
+++ b/dev-tools/mage/gotool/licenser.go
@@ -0,0 +1,37 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package gotool
+
+import (
+	"github.com/magefile/mage/sh"
+)
+
+type goLicenser func(opts ...ArgOpt) error
+
+// Licenser runs `go-licenser` and provides optionals for adding command line arguments.
+var Licenser goLicenser = runGoLicenser
+
+func runGoLicenser(opts ...ArgOpt) error {
+	args := buildArgs(opts).build()
+	return sh.RunV("go-licenser", args...)
+}
+
+func (goLicenser) Check() ArgOpt                 { return flagBoolIf("-d", true) }
+func (goLicenser) License(license string) ArgOpt { return flagArgIf("-license", license) }
+func (goLicenser) Exclude(path string) ArgOpt    { return flagArgIf("-exclude", path) }
+func (goLicenser) Path(path string) ArgOpt       { return posArg(path) }
diff --git a/dev-tools/mage/install.go b/dev-tools/mage/install.go
new file mode 100644
index 000000000000..9b2c7795c631
--- /dev/null
+++ b/dev-tools/mage/install.go
@@ -0,0 +1,49 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package mage
+
+import (
+	"path/filepath"
+
+	"github.com/pkg/errors"
+
+	"github.com/elastic/beats/dev-tools/mage/gotool"
+)
+
+var (
+	// GoLicenserImportPath controls the import path used to install go-licenser.
+	GoLicenserImportPath = "github.com/elastic/go-licenser"
+)
+
+// InstallVendored uses go get to install a command from its vendored source
+func InstallVendored(importPath string) error {
+	beatDir, err := ElasticBeatsDir()
+	if err != nil {
+		return errors.Wrap(err, "failed to obtain beats repository path")
+	}
+
+	get := gotool.Get
+	return get(
+		get.Package(filepath.Join(beatDir, "vendor", importPath)),
+	)
+}
+
+// InstallGoLicenser target installs go-licenser
+func InstallGoLicenser() error {
+	return InstallVendored(GoLicenserImportPath)
+}
diff --git a/dev-tools/mage/target/common/check.go b/dev-tools/mage/target/common/check.go
index 16ad95689497..d5038c99c947 100644
--- a/dev-tools/mage/target/common/check.go
+++ b/dev-tools/mage/target/common/check.go
@@ -39,3 +39,8 @@ func Check() {
 	deps = append(deps, devtools.Check)
 	mg.SerialDeps(deps...)
 }
+
+// CheckLicenseHeaders checks license headers
+func CheckLicenseHeaders() {
+	mg.Deps(devtools.CheckLicenseHeaders)
+}
diff --git a/dev-tools/mage/target/common/fmt.go b/dev-tools/mage/target/common/fmt.go
index 69f45fd4a824..9405d69ca487 100644
--- a/dev-tools/mage/target/common/fmt.go
+++ b/dev-tools/mage/target/common/fmt.go
@@ -27,3 +27,8 @@ import (
 func Fmt() {
 	mg.Deps(devtools.Format)
 }
+
+// AddLicenseHeaders adds license headers
+func AddLicenseHeaders() {
+	mg.Deps(devtools.AddLicenseHeaders)
+}
diff --git a/libbeat/scripts/Makefile b/libbeat/scripts/Makefile
index 180d567f0332..8c6969d3bca8 100755
--- a/libbeat/scripts/Makefile
+++ b/libbeat/scripts/Makefile
@@ -125,17 +125,15 @@ check: check-headers mage ## @build Checks project and source code if everything
 	@mage check
 
 .PHONY: $(.OVER)check-headers
-$(.OVER)check-headers:
+$(.OVER)check-headers: mage
 ifndef CHECK_HEADERS_DISABLED
-	@go get -u github.com/elastic/go-licenser
-	@go-licenser -d -license ${LICENSE}
+	@mage checkLicenseHeaders
 endif
 
 .PHONY: $(.OVER)add-headers
-$(.OVER)add-headers:
+$(.OVER)add-headers: mage
 ifndef CHECK_HEADERS_DISABLED
-	@go get github.com/elastic/go-licenser
-	@go-licenser -license ${LICENSE}
+	@mage addLicenseHeaders
 endif
 
 .PHONY: fmt
diff --git a/magefile.go b/magefile.go
index e89775b07ba2..25eddd0acef6 100644
--- a/magefile.go
+++ b/magefile.go
@@ -25,11 +25,11 @@ import (
 	"path/filepath"
 
 	"github.com/magefile/mage/mg"
-	"github.com/magefile/mage/sh"
 	"github.com/pkg/errors"
 	"go.uber.org/multierr"
 
 	devtools "github.com/elastic/beats/dev-tools/mage"
+	"github.com/elastic/beats/dev-tools/mage/gotool"
 )
 
 var (
@@ -87,21 +87,54 @@ func PackageBeatDashboards() error {
 // Fmt formats code and adds license headers.
 func Fmt() {
 	mg.Deps(devtools.GoImports, devtools.PythonAutopep8)
-	mg.Deps(addLicenseHeaders)
+	mg.Deps(AddLicenseHeaders)
 }
 
-// addLicenseHeaders adds ASL2 headers to .go files outside of x-pack and
+// AddLicenseHeaders adds ASL2 headers to .go files outside of x-pack and
 // add Elastic headers to .go files in x-pack.
-func addLicenseHeaders() error {
+func AddLicenseHeaders() error {
 	fmt.Println(">> fmt - go-licenser: Adding missing headers")
 
-	if err := sh.Run("go", "get", devtools.GoLicenserImportPath); err != nil {
-		return err
-	}
+	mg.Deps(devtools.InstallGoLicenser)
+
+	licenser := gotool.Licenser
+
+	return multierr.Combine(
+		licenser(
+			licenser.License("ASL2"),
+			licenser.Exclude("x-pack"),
+			licenser.Exclude("generator/beat/{beat}"),
+			licenser.Exclude("generator/metricbeat/{beat}"),
+		),
+		licenser(
+			licenser.License("Elastic"),
+			licenser.Path("x-pack"),
+		),
+	)
+}
+
+// CheckLicenseHeaders checks ASL2 headers in .go files outside of x-pack and
+// checks Elastic headers in .go files in x-pack.
+func CheckLicenseHeaders() error {
+	fmt.Println(">> fmt - go-licenser: Checking for missing headers")
+
+	mg.Deps(devtools.InstallGoLicenser)
+
+	licenser := gotool.Licenser
 
 	return multierr.Combine(
-		sh.RunV("go-licenser", "-license", "ASL2", "-exclude", "x-pack"),
-		sh.RunV("go-licenser", "-license", "Elastic", "x-pack"),
+		licenser(
+			licenser.Check(),
+			licenser.License("ASL2"),
+			licenser.Exclude("x-pack"),
+			licenser.Exclude("generator/beat/{beat}"),
+			licenser.Exclude("generator/metricbeat/{beat}"),
+		),
+		licenser(
+			licenser.Check(),
+			licenser.License("Elastic"),
+			licenser.Path("x-pack"),
+		),
 	)
 }
 
diff --git a/vendor/github.com/elastic/go-licenser/CONTRIBUTING.md b/vendor/github.com/elastic/go-licenser/CONTRIBUTING.md
new file mode 100644
index 000000000000..0c8d15b6f59e
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/CONTRIBUTING.md
@@ -0,0 +1,47 @@
+# Contributing
+
+Contributions are very welcome, this includes documentation, tutorials, bug reports, issues, feature requests, feature implementations, pull requests or simply organizing the repository issues.
+
+*Pull requests that contain changes on the code base **and** related documentation, e.g. for a new feature, shall remain a single, atomic one.*
+
+## Building From Source
+
+### Environment Prerequisites
+
+To install the latest changes directly from source code, you will need to have `go` installed with `$GOPATH` defined. If you need assistance with this please follow [golangbootcamp guide](http://www.golangbootcamp.com/book/get_setup#cha-get_setup).
+
+### Actual installation commands
+
+**Make sure you have followed through the environment requisites**
+
+```sh
+go get -u github.com/elastic/go-licenser
+```
+
+## Reporting Issues
+
+If you have found an issue or defect in `go-licenser` or the latest documentation, use the GitHub [issue tracker](https://github.com/elastic/go-licenser/issues) to report the problem. Make sure to follow the template provided for you to provide all the useful details possible.
+
+
+### Code Contribution Guidelines
+
+For the benefit of all, here are some recommendations with regards to your PR:
+
+* Go ahead and fork the project and make your changes.  We encourage pull requests to allow for review and discussion of code changes.
+* As a best practice it's best to open an Issue on the repository before submitting a PR.
+* When you’re ready to create a pull request, be sure to:
+    * Sign your commit messages, see [DCO details](https://probot.github.io/apps/dco/)
+    * Have test cases for the new code. If you have questions about how to do this, please ask in your pull request.
+    * Run `make format` and `make lint`.
+    * Ensure that `make unit` succeeds.
+
+
+### Golden Files
+
+If you're working with a function that relies on testdata or golden files, you might need to update those if your
+change is modifying that logic.
+
+```console
+$ make update-golden-files
+ok  	github.com/elastic/go-licenser	0.029s
+```
diff --git a/vendor/github.com/elastic/go-licenser/LICENSE b/vendor/github.com/elastic/go-licenser/LICENSE
new file mode 100644
index 000000000000..0d4ee7515f06
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/LICENSE
@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright 2018 Elasticsearch B.V.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
diff --git a/vendor/github.com/elastic/go-licenser/Makefile b/vendor/github.com/elastic/go-licenser/Makefile
new file mode 100644
index 000000000000..c60e3872397b
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/Makefile
@@ -0,0 +1,105 @@
+export VERSION := 0.2.0
+OWNER ?= elastic
+REPO ?= go-licenser
+TEST_UNIT_FLAGS ?= -timeout 10s -p 4 -race -cover
+TEST_UNIT_PACKAGE ?= ./...
+GOLINT_PRESENT := $(shell command -v golint 2> /dev/null)
+GOIMPORTS_PRESENT := $(shell command -v goimports 2> /dev/null)
+GORELEASER_PRESENT := $(shell command -v goreleaser 2> /dev/null)
+RELEASED = $(shell git tag -l $(VERSION))
+DEFAULT_LDFLAGS ?= -X main.version=$(VERSION)-dev -X main.commit=$(shell git rev-parse HEAD)
+
+define HELP
+/////////////////////////////////////////
+/\t$(REPO) Makefile \t\t/
+/////////////////////////////////////////
+
+## Build target
+
+- build:                  It will build $(REPO) for the current architecture in bin/$(REPO).
+- install:                It will install $(REPO) in the current system (by default in $(GOPATH)/bin/$(REPO)).
+
+## Development targets
+
+- deps:                   It will install the dependencies required to run developemtn targets.
+- unit:                   Runs the unit tests.
+- lint:                   Runs the linters.
+- format:                 Formats the source files according to gofmt, goimports and go-licenser.
+- update-golden-files:    Updates the test golden files.
+
+## Release targets
+
+- release:                Creates and publishes a new release matching the VERSION variable.
+- snapshot:               Creates a snapshot locally in the dist/ folder.
+
+endef
+export HELP
+
+.DEFAULT: help
+.PHONY: help
+help:
+	@ echo "$$HELP"
+
+.PHONY: deps
+deps:
+ifndef GOLINT_PRESENT
+	@ go get -u golang.org/x/lint/golint
+endif
+ifndef GOIMPORTS_PRESENT
+	@ go get -u golang.org/x/tools/cmd/goimports
+endif
+
+.PHONY: release_deps
+release_deps:
+ifndef GORELEASER_PRESENT
+	@ echo "-> goreleaser not found in path, please install it following the instructions:"
+	@ echo "-> https://goreleaser.com/introduction"
+	@ exit 1
+endif
+
+.PHONY: update-golden-files
+update-golden-files:
+	$(eval GOLDEN_FILE_PACKAGES := "github.com/$(OWNER)/$(REPO)")
+	@ go test $(GOLDEN_FILE_PACKAGES) -update
+
+.PHONY: unit
+unit:
+	@ go test $(TEST_UNIT_FLAGS) $(TEST_UNIT_PACKAGE)
+
+.PHONY: build
+build: deps
+	@ go build -o bin/$(REPO) -ldflags="$(DEFAULT_LDFLAGS)"
+
+.PHONY: install
+install: deps
+	@ go install
+
+.PHONY: lint
+lint: build
+	@ golint -set_exit_status $(shell go list ./...)
+	@ gofmt -d -e -s .
+	@ ./bin/go-licenser -d -exclude golden
+
+.PHONY: format
+format: deps build
+	@ gofmt -e -w -s .
+	@ goimports -w .
+	@ ./bin/go-licenser -exclude golden
+
+.PHONY: release
+release: deps release_deps
+	@ echo "-> Releasing $(REPO) $(VERSION)..."
+	@ git fetch upstream
+ifeq ($(strip $(RELEASED)),)
+	@ echo "-> Creating and pushing a new tag $(VERSION)..."
+	@ git tag $(VERSION)
+	@ git push upstream $(VERSION)
+	@ goreleaser release --rm-dist
+else
+	@ echo "-> git tag $(VERSION) already present, skipping release..."
+endif
+
+.PHONY: snapshot
+snapshot: deps release_deps
+	@ echo "-> Snapshotting $(REPO) $(VERSION)..."
+	@ goreleaser release --snapshot --rm-dist
diff --git a/vendor/github.com/elastic/go-licenser/NOTICE b/vendor/github.com/elastic/go-licenser/NOTICE
new file mode 100644
index 000000000000..4972cec5acdd
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/NOTICE
@@ -0,0 +1,5 @@
+Elastic go-licenser
+Copyright 2018 Elasticsearch B.V.
+
+This product includes software developed at
+Elasticsearch, B.V. (https://www.elastic.co/).
diff --git a/vendor/github.com/elastic/go-licenser/README.md b/vendor/github.com/elastic/go-licenser/README.md
new file mode 100644
index 000000000000..435b4b1cc3cb
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/README.md
@@ -0,0 +1,46 @@
+# Go Licenser [![Build Status](https://travis-ci.org/elastic/go-licenser.svg?branch=master)](https://travis-ci.org/elastic/go-licenser)
+
+Small zero dependency license header checker for source files. The aim of this project is to provide a common
+binary that can be used to ensure that code source files contain a license header. It's unlikely that this project
+is useful outside of Elastic **_at the current stage_**, but the `licensing` package can be used as a building block.
+
+## Supported Licenses
+
+* Apache 2.0
+* Elastic
+
+## Supported languages
+
+* Go
+
+## Installing
+
+```
+go get -u github.com/elastic/go-licenser
+```
+
+## Usage
+
+```
+Usage: go-licenser [flags] [path]
+
+  go-licenser walks the specified path recursiely and appends a license Header if the current
+  header doesn't match the one found in the file.
+
+Options:
+
+  -d	skips rewriting files and returns exitcode 1 if any discrepancies are found.
+  -exclude value
+    	path to exclude (can be specified multiple times).
+  -ext string
+    	sets the file extension to scan for. (default ".go")
+  -license string
+    	sets the license type to check: ASL2, Elastic (default "ASL2")
+  -version
+    	prints out the binary version.
+```
+
+## Contributing
+
+See [CONTRIBUTING.md](./CONTRIBUTING.md).
+
diff --git a/vendor/github.com/elastic/go-licenser/appveyor.yml b/vendor/github.com/elastic/go-licenser/appveyor.yml
new file mode 100644
index 000000000000..2292bcb2d933
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/appveyor.yml
@@ -0,0 +1,38 @@
+version: "{build}"
+
+# Source Config
+
+clone_folder: c:\gopath\src\github.com\elastic\go-licenser
+
+# Build host
+
+environment:
+  GOPATH: c:\gopath
+  GOVERSION: 1.10
+
+# Build
+
+install:
+  # Install the specific Go version.
+  - rmdir c:\go /s /q
+  - appveyor DownloadFile https://storage.googleapis.com/golang/go%GOVERSION%.windows-amd64.msi
+  - msiexec /i go%GOVERSION%.windows-amd64.msi /q
+  - choco install bzr
+  - set Path=c:\go\bin;c:\gopath\bin;C:\Program Files (x86)\Bazaar\;C:\Program Files\Mercurial\%Path%
+  - go version
+  - go env
+
+before_build:
+  - go get -u golang.org/x/lint/golint
+  - go get -u golang.org/x/tools/cmd/goimports
+  - golint -set_exit_status .
+  - gofmt -d -e -s .
+  - goimports -d .
+
+build_script:
+  - appveyor AddCompilationMessage "Starting Compilation"
+  - go install github.com/elastic/go-licenser
+
+test_script:
+  - go-licenser -d -exclude golden
+  - go test -timeout 10s -p 4 -race -cover ./...
diff --git a/vendor/github.com/elastic/go-licenser/error.go b/vendor/github.com/elastic/go-licenser/error.go
new file mode 100644
index 000000000000..5c40faa3b2cb
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/error.go
@@ -0,0 +1,39 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package main
+
+// Error wraps a normal error with an Exitcode.
+type Error struct {
+	err  error
+	code int
+}
+
+func (e Error) Error() string {
+	if e.err != nil {
+		return e.err.Error()
+	}
+	return "<nil>"
+}
+
+// Code returns the exitcode for the error
+func Code(e error) int {
+	if err, ok := e.(*Error); ok {
+		return err.code
+	}
+	return 0
+}
diff --git a/vendor/github.com/elastic/go-licenser/go.mod b/vendor/github.com/elastic/go-licenser/go.mod
new file mode 100644
index 000000000000..89b964cbf36b
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/go.mod
@@ -0,0 +1 @@
+module github.com/elastic/go-licenser
diff --git a/vendor/github.com/elastic/go-licenser/licensing/doc.go b/vendor/github.com/elastic/go-licenser/licensing/doc.go
new file mode 100644
index 000000000000..3fcc1ac56b34
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/licensing/doc.go
@@ -0,0 +1,20 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+// Package licensing provides a set of functions that read the top
+// lines of a file and can determine if they match a specific header.
+package licensing
diff --git a/vendor/github.com/elastic/go-licenser/licensing/license.go b/vendor/github.com/elastic/go-licenser/licensing/license.go
new file mode 100644
index 000000000000..fad14c14ed9a
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/licensing/license.go
@@ -0,0 +1,132 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package licensing
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"io"
+	"io/ioutil"
+	"os"
+	"reflect"
+	"strings"
+)
+
+var (
+	startPrefixes = []string{"// Copyright", "// copyright", "// Licensed", "// licensed"}
+	endPrefixes   = []string{"package ", "// Package ", "// +build ", "// Code generated by", "// code generated by"}
+
+	errHeaderIsTooShort = errors.New("header is too short")
+)
+
+// ContainsHeader reads the first N lines of a file and checks if the header
+// matches the one that is expected
+func ContainsHeader(r io.Reader, headerLines []string) bool {
+	var found []string
+	var scanner = bufio.NewScanner(r)
+
+	for scanner.Scan() {
+		found = append(found, scanner.Text())
+	}
+
+	if len(found) < len(headerLines) {
+		return false
+	}
+
+	if !reflect.DeepEqual(found[:len(headerLines)], headerLines) {
+		return false
+	}
+
+	return true
+}
+
+// RewriteFileWithHeader reads a file from a path and rewrites it with a header
+func RewriteFileWithHeader(path string, header []byte) error {
+	if len(header) < 2 {
+		return errHeaderIsTooShort
+	}
+
+	info, err := os.Stat(path)
+	if err != nil {
+		return err
+	}
+
+	origin, err := ioutil.ReadFile(path)
+	if err != nil {
+		return err
+	}
+
+	data := RewriteWithHeader(origin, header)
+	return ioutil.WriteFile(path, data, info.Mode())
+}
+
+// RewriteWithHeader rewrites the src byte buffers header with the new header.
+func RewriteWithHeader(src []byte, header []byte) []byte {
+	// Ensures that the header includes two break lines as the last bytes
+	for !reflect.DeepEqual(header[len(header)-2:], []byte("\n\n")) {
+		header = append(header, []byte("\n")...)
+	}
+
+	var oldHeader = headerBytes(bytes.NewReader(src))
+	return bytes.Replace(src, oldHeader, header, 1)
+}
+
+// headerBytes detects the header lines of an io.Reader contents and returns
+// what it considerst to be the header as a slice of bytes.
+func headerBytes(r io.Reader) []byte {
+	var scanner = bufio.NewScanner(r)
+	var replaceableHeader []byte
+	var continuedHeader bool
+	for scanner.Scan() {
+		var t = scanner.Text()
+
+		for i := range endPrefixes {
+			if strings.HasPrefix(t, endPrefixes[i]) {
+				return replaceableHeader
+			}
+		}
+
+		for i := range startPrefixes {
+			if strings.HasPrefix(t, startPrefixes[i]) {
+				continuedHeader = true
+			}
+		}
+
+		if continuedHeader {
+			replaceableHeader = append(replaceableHeader, []byte(t+"\n")...)
+		}
+	}
+
+	return replaceableHeader
+}
+
+// containsHeaderLine reads the first N lines of a file and checks if the header
+// matches the one that is expected
+func containsHeaderLine(r io.Reader, headerLines []string) bool {
+	var scanner = bufio.NewScanner(r)
+	for scanner.Scan() {
+		for i := range headerLines {
+			if scanner.Text() == headerLines[i] {
+				return true
+			}
+		}
+	}
+
+	return false
+}
diff --git a/vendor/github.com/elastic/go-licenser/main.go b/vendor/github.com/elastic/go-licenser/main.go
new file mode 100644
index 000000000000..e04a421eaf9a
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/main.go
@@ -0,0 +1,236 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/elastic/go-licenser/licensing"
+)
+
+const (
+	defaultExt     = ".go"
+	defaultPath    = "."
+	defaultLicense = "ASL2"
+	defaultFormat  = "%s: is missing the license header\n"
+)
+
+const (
+	exitDefault = iota
+	exitSourceNeedsToBeRewritten
+	exitFailedToStatTree
+	exitFailedToStatFile
+	exitFailedToWalkPath
+	exitFailedToOpenWalkFile
+	errFailedRewrittingFile
+	errUnknownLicense
+)
+
+var usageText = `
+Usage: go-licenser [flags] [path]
+
+  go-licenser walks the specified path recursiely and appends a license Header if the current
+  header doesn't match the one found in the file.
+
+Options:
+
+`[1:]
+
+// Headers is the map of supported licenses
+var Headers = map[string][]string{
+	"ASL2": {
+		`// Licensed to Elasticsearch B.V. under one or more contributor`,
+		`// license agreements. See the NOTICE file distributed with`,
+		`// this work for additional information regarding copyright`,
+		`// ownership. Elasticsearch B.V. licenses this file to you under`,
+		`// the Apache License, Version 2.0 (the "License"); you may`,
+		`// not use this file except in compliance with the License.`,
+		`// You may obtain a copy of the License at`,
+		`//`,
+		`//     http://www.apache.org/licenses/LICENSE-2.0`,
+		`//`,
+		`// Unless required by applicable law or agreed to in writing,`,
+		`// software distributed under the License is distributed on an`,
+		`// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY`,
+		`// KIND, either express or implied.  See the License for the`,
+		`// specific language governing permissions and limitations`,
+		`// under the License.`,
+	},
+	"Elastic": {
+		`// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one`,
+		`// or more contributor license agreements. Licensed under the Elastic License;`,
+		`// you may not use this file except in compliance with the Elastic License.`,
+	},
+}
+
+var (
+	dryRun             bool
+	showVersion        bool
+	extension          string
+	args               []string
+	license            string
+	exclude            sliceFlag
+	defaultExludedDirs = []string{"vendor", ".git"}
+)
+
+type sliceFlag []string
+
+func (f *sliceFlag) String() string {
+	var s string
+	for _, i := range *f {
+		s += i + " "
+	}
+	return s
+}
+
+func (f *sliceFlag) Set(value string) error {
+	*f = append(*f, value)
+	return nil
+}
+
+func init() {
+	flag.Var(&exclude, "exclude", `path to exclude (can be specified multiple times).`)
+	flag.BoolVar(&dryRun, "d", false, `skips rewriting files and returns exitcode 1 if any discrepancies are found.`)
+	flag.BoolVar(&showVersion, "version", false, `prints out the binary version.`)
+	flag.StringVar(&extension, "ext", defaultExt, "sets the file extension to scan for.")
+	flag.StringVar(&license, "license", defaultLicense, "sets the license type to check: ASL2, Elastic")
+	flag.Usage = usageFlag
+	flag.Parse()
+	args = flag.Args()
+}
+
+func main() {
+	if showVersion {
+		fmt.Printf("go-licenser %s (%s)\n", version, commit)
+		return
+	}
+
+	err := run(args, license, exclude, extension, dryRun, os.Stdout)
+	if err != nil && err.Error() != "<nil>" {
+		fmt.Fprint(os.Stderr, err)
+	}
+
+	os.Exit(Code(err))
+}
+
+func run(args []string, license string, exclude []string, ext string, dry bool, out io.Writer) error {
+	header, ok := Headers[license]
+	if !ok {
+		return &Error{err: fmt.Errorf("unknown license: %s", license), code: errUnknownLicense}
+	}
+
+	var headerBytes []byte
+	for i := range header {
+		headerBytes = append(headerBytes, []byte(header[i])...)
+		headerBytes = append(headerBytes, []byte("\n")...)
+	}
+
+	var path = defaultPath
+	if len(args) > 0 {
+		path = args[0]
+	}
+
+	if _, err := os.Stat(path); err != nil {
+		return &Error{err: err, code: exitFailedToStatTree}
+	}
+
+	return walk(path, ext, license, headerBytes, exclude, dry, out)
+}
+
+func reportFile(out io.Writer, f string) {
+	cwd, _ := filepath.Abs(filepath.Dir(os.Args[0]))
+	rel, err := filepath.Rel(cwd, f)
+	if err != nil {
+		rel = f
+	}
+	fmt.Fprintf(out, defaultFormat, rel)
+}
+
+func walk(p, ext, license string, headerBytes []byte, exclude []string, dry bool, out io.Writer) error {
+	var err error
+	filepath.Walk(p, func(path string, info os.FileInfo, walkErr error) error {
+		if walkErr != nil {
+			err = &Error{err: walkErr, code: exitFailedToWalkPath}
+			return walkErr
+		}
+
+		var currentPath = cleanPathPrefixes(
+			strings.Replace(path, p, "", 1),
+			[]string{string(os.PathSeparator)},
+		)
+
+		var excludedDir = info.IsDir() && stringInSlice(info.Name(), defaultExludedDirs)
+		if needsExclusion(currentPath, exclude) || excludedDir {
+			return filepath.SkipDir
+		}
+
+		if e := addOrCheckLicense(path, ext, license, headerBytes, info, dry, out); e != nil {
+			err = e
+		}
+
+		return nil
+	})
+
+	return err
+}
+
+func addOrCheckLicense(path, ext, license string, headerBytes []byte, info os.FileInfo, dry bool, out io.Writer) error {
+	if info.IsDir() || filepath.Ext(path) != ext {
+		return nil
+	}
+
+	f, e := os.Open(path)
+	if e != nil {
+		return &Error{err: e, code: exitFailedToOpenWalkFile}
+	}
+	defer f.Close()
+
+	if licensing.ContainsHeader(f, Headers[license]) {
+		return nil
+	}
+
+	if dry {
+		reportFile(out, path)
+		return &Error{code: exitSourceNeedsToBeRewritten}
+	}
+
+	if err := licensing.RewriteFileWithHeader(path, headerBytes); err != nil {
+		return &Error{err: err, code: errFailedRewrittingFile}
+	}
+
+	return nil
+}
+
+func stringInSlice(a string, list []string) bool {
+	for _, b := range list {
+		if b == a {
+			return true
+		}
+	}
+	return false
+}
+
+func usageFlag() {
+	fmt.Fprintf(os.Stderr, usageText)
+	flag.PrintDefaults()
+}
diff --git a/vendor/github.com/elastic/go-licenser/path.go b/vendor/github.com/elastic/go-licenser/path.go
new file mode 100644
index 000000000000..fad555b0592d
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/path.go
@@ -0,0 +1,54 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package main
+
+import (
+	"os"
+	"strings"
+)
+
+func needsExclusion(path string, exclude []string) bool {
+	for _, excluded := range exclude {
+		excluded = cleanPathSuffixes(excluded, []string{"*", string(os.PathSeparator)})
+		if strings.HasPrefix(path, excluded) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func cleanPathSuffixes(path string, sufixes []string) string {
+	for _, suffix := range sufixes {
+		for strings.HasSuffix(path, suffix) && len(path) > 0 {
+			path = path[:len(path)-len(suffix)]
+		}
+	}
+
+	return path
+}
+
+func cleanPathPrefixes(path string, prefixes []string) string {
+	for _, prefix := range prefixes {
+		for strings.HasPrefix(path, prefix) && len(path) > 0 {
+			path = path[len(prefix):]
+		}
+	}
+
+	return path
+}
diff --git a/vendor/github.com/elastic/go-licenser/version.go b/vendor/github.com/elastic/go-licenser/version.go
new file mode 100644
index 000000000000..426d12340859
--- /dev/null
+++ b/vendor/github.com/elastic/go-licenser/version.go
@@ -0,0 +1,23 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package main
+
+var (
+	version string
+	commit  string
+)
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 78b6d1cd0d10..7a99840feab7 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -1366,6 +1366,22 @@
 			"version": "v0.4.0",
 			"versionExact": "v0.4.0"
 		},
+		{
+			"checksumSHA1": "qM65VcezrEdAS7HdzRAh3RGnwWw=",
+			"path": "github.com/elastic/go-licenser",
+			"revision": "2b2abd4ee9b58025ebd0630d7621cfd7619f58ac",
+			"revisionTime": "2018-08-30T07:58:35Z",
+			"version": "0.2.0",
+			"versionExact": "0.2.0"
+		},
+		{
+			"checksumSHA1": "R/WGo2p8J0KsCMu8nrbemg+iqIw=",
+			"path": "github.com/elastic/go-licenser/licensing",
+			"revision": "2b2abd4ee9b58025ebd0630d7621cfd7619f58ac",
+			"revisionTime": "2018-08-30T07:58:35Z",
+			"version": "0.2.0",
+			"versionExact": "0.2.0"
+		},
 		{
 			"checksumSHA1": "+nIsRlnG94bUQI6IQd4Mcj4diTY=",
 			"path": "github.com/elastic/go-lookslike",