Moving here from fortio/dflag#50 (#1)

* adding files from fortio/dflag#50 where this was initially done

* update package path

* update test to use canonical package name, add to readme

* adding workflows

* refactor/inline some type conversion and start returning error lists instead of logging. also testing that linter ci should fail

* fix lints

* removed dependency on assert and log, 0 dependencies now

* add back depguard - yet OpenPeeDeeP/depguard#66. add note about go version(s)

.github/dependabot.yml

@@ -0,0 +1,16 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+updates:
+  - package-ecosystem: "gomod"
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "daily"
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      # Check for updates to GitHub Actions every week
+      interval: "weekly"

.github/workflows/codecov.yml

@@ -0,0 +1,21 @@
+name: "Code Coverage"
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - uses: actions/setup-go@v4
+      with:
+          go-version: '1.20'
+    - name: Run test coverage
+      run: go test -race -coverprofile=coverage.out -covermode=atomic ./...
+    - uses: codecov/codecov-action@v3
+      with:
+        files: coverage.out

.github/workflows/codeql-analysis.yml

@@ -0,0 +1,67 @@
+# For most projects, this workflow file will not need changing; you simply need
+# to commit it to your repository.
+#
+# You may wish to alter this file to override the set of languages analyzed,
+# or to provide custom queries or build logic.
+#
+# ******** NOTE ********
+# We have attempted to detect the languages in your repository. Please check
+# the `language` matrix defined below to confirm you have the correct set of
+# supported CodeQL languages.
+#
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [ main ]
+  schedule:
+    - cron: '42 20 * * 3'
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'go' ]
+        # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python', 'ruby' ]
+        # Learn more about CodeQL language support at https://aka.ms/codeql-docs/language-support
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # pin@v3
+
+      # Initializes the CodeQL tools for scanning.
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@cdcdbb579706841c47f7063dda365e292e5cad7a # pin@v2
+        with:
+          languages: ${{ matrix.language }}
+          # If you wish to specify custom queries, you can do so here or in a config file.
+          # By default, queries listed here will override any specified in a config file.
+          # Prefix the list here with "+" to use these queries and those in the config file.
+          # Details on CodeQL's query packs refer to : https://docs.github.com/en/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/configuring-code-scanning#using-queries-in-ql-packs
+          # queries: security-extended,security-and-quality
+
+      # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
+      # If this step fails, then you should remove it and run the build manually (see below)
+      - name: Autobuild
+        uses: github/codeql-action/autobuild@cdcdbb579706841c47f7063dda365e292e5cad7a # pin@v2
+
+      # ℹ️ Command-line programs to run using the OS shell.
+      # 📚 See https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idstepsrun
+      #   If the Autobuild fails above, remove it and uncomment the following three lines. 
+      #   modify them (or add more) to build your code if your project, please refer to the EXAMPLE below for guidance.
+      # - run: |
+      #   echo "Run, Build Application using script"
+      #   ./location_of_script_within_repo/buildscript.sh
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@cdcdbb579706841c47f7063dda365e292e5cad7a # pin@v2

.github/workflows/gochecks.yml

@@ -0,0 +1,26 @@
+name: go-checks
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [main]
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # pin@v3
+      - name: Setup Go environment
+        uses: actions/setup-go@93397bea11091df50f3d7e59dc26a7711a8bcfbe # pin@v4
+        with:
+          go-version: '1.20'
+          check-latest: true
+      - name: Run Vulncheck
+        run: |
+          go install golang.org/x/vuln/cmd/govulncheck@latest
+          govulncheck ./...
+      - name: Run golangci-lint
+        uses: golangci/golangci-lint-action@3a919529898de77ec3da873e3063ca4b10e7f5cc # pin@v3

.golangci.yml

@@ -0,0 +1,168 @@
+# Config for golangci-lint
+
+# output configuration options
+
+# all available settings of specific linters
+linters-settings:
+  gocritic:
+    disabled-checks:
+      - ifElseChain
+  dupl:
+    # tokens count to trigger issue, 150 by default
+    threshold: 100
+  exhaustive:
+    # indicates that switch statements are to be considered exhaustive if a
+    # 'default' case is present, even if all enum members aren't listed in the
+    # switch
+    default-signifies-exhaustive: false
+  funlen:
+    lines: 140
+    statements: 70
+  gocognit:
+    # minimal code complexity to report, 30 by default (but we recommend 10-20)
+    min-complexity: 42
+  nestif:
+    # minimal complexity of if statements to report, 5 by default
+    min-complexity: 4
+  gocyclo:
+    # minimal code complexity to report, 30 by default (but we recommend 10-20)
+    min-complexity: 30
+  godot:
+    # check all top-level comments, not only declarations
+    check-all: false
+  govet:
+    # report about shadowed variables
+    check-shadowing: true
+    # settings per analyzer
+    settings:
+      printf: # analyzer name, run `go tool vet help` to see all analyzers
+        funcs: # run `go tool vet help printf` to see available settings for `printf` analyzer
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Infof
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Warnf
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Errorf
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Fatalf
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Printf
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).FErrf
+    enable-all: true
+    disable-all: false
+  lll:
+    # max line length, lines longer will be reported. Default is 120.
+    # '\t' is counted as 1 character by default, and can be changed with the tab-width option
+    line-length: 132
+    # tab width in spaces. Default to 1.
+    tab-width: 1
+  misspell:
+    # Correct spellings using locale preferences for US or UK.
+    # Default is to use a neutral variety of English.
+    # Setting locale to US will correct the British spelling of 'colour' to 'color'.
+    locale: US
+    ignore-words:
+      - fortio
+  nakedret:
+    # make an issue if func has more lines of code than this setting and it has naked returns; default is 30
+    max-func-lines: 30
+  nolintlint:
+    require-specific: true
+  whitespace:
+    multi-if: false   # Enforces newlines (or comments) after every multi-line if statement
+    multi-func: false # Enforces newlines (or comments) after every multi-line function signature
+  gofumpt:
+    # Choose whether or not to use the extra rules that are disabled
+    # by default
+    extra-rules: false
+
+
+linters:
+  disable:
+    # bad ones:
+    - musttag
+    # Deprecated ones:
+    - scopelint
+    - golint
+    - interfacer
+    - maligned
+    - varcheck
+    - structcheck
+    - nosnakecase
+    - deadcode
+    # Weird/bad ones:
+    - wsl
+    - nlreturn
+    - gochecknoinits
+    - gochecknoglobals
+    - gomnd
+    - testpackage
+    - wrapcheck
+    - exhaustivestruct
+    - tagliatelle
+    - nonamedreturns
+    - varnamelen
+    - exhaustruct # seems like a good idea at first but actually a pain and go does have zero values for a reason.
+# TODO consider putting these back, when they stop being bugged (ifshort, wastedassign,...)
+    - paralleltest
+    - thelper
+    - forbidigo
+    - ifshort
+    - wastedassign
+    - cyclop
+    - forcetypeassert
+    - ireturn
+  enable-all: true
+  disable-all: false
+  # Must not use fast: true in newer golangci-lint or it'll just skip a bunch of linter instead of doing caching like before (!)
+  fast: false
+
+
+issues:
+  # Excluding configuration per-path, per-linter, per-text and per-source
+  exclude-rules:
+    # Exclude some linters from running on tests files.
+    - path: _test\.go
+      linters:
+        - gocyclo
+        - errcheck
+        - dupl
+        - gosec
+        - gochecknoinits
+        - gochecknoglobals
+        - forcetypeassert
+        - nosnakecase
+        - noctx
+
+    # Exclude lll issues for long lines with go:generate
+    - linters:
+        - lll
+      source: "^//go:generate "
+    - linters:
+        - goerr113
+      text: "do not define dynamic errors"
+    - linters:
+        - govet
+      text: "fieldalignment:"
+    - linters:
+        - godox
+      text: "TODO"
+    - linters:
+        - nosnakecase
+      text: "grpc_|_SERVING|O_"
+
+  # Maximum issues count per one linter. Set to 0 to disable. Default is 50.
+  max-issues-per-linter: 0
+
+  # Maximum count of issues with the same text. Set to 0 to disable. Default is 3.
+  max-same-issues: 0
+
+severity:
+  # Default value is empty string.
+  # Set the default severity for issues. If severity rules are defined and the issues
+  # do not match or no severity is provided to the rule this will be the default
+  # severity applied. Severities should match the supported severity names of the
+  # selected out format.
+  # - Code climate: https://docs.codeclimate.com/docs/issues#issue-severity
+  # -   Checkstyle: https://checkstyle.sourceforge.io/property_types.html#severity
+  # -       Github: https://help.github.com/en/actions/reference/workflow-commands-for-github-actions#setting-an-error-message
+  default-severity: error
+
+  # The default value is false.
+  # If set to true severity-rules regular expressions become case sensitive.
+  case-sensitive: false

README.md

@@ -1,2 +1,38 @@
 # struct2env
 Convert between go structures to environment variable and back (for structured config <-> shell env)
+
+There are many go packages that are doing environment to go struct config (for instance https://github.com/kelseyhightower/envconfig) but I didn't find one doing the inverse and we needed to set a bunch of environment variables for shell and other tools to get some configuration structured as JSON and Go object, so this was born. For symetry the reverse was also added (history of commit on https://github.com/fortio/dflag/pull/50/commits)
+
+Standalone package with 0 dependencies outside of the go standard library. Developed with go 1.20 but tested with go as old as 1.17
+but should works with pretty much any go version, as it only depends on reflection and strconv.
+
+
+The unit test has a fairly extensive example on how:
+```go
+type FooConfig struct {
+	Foo          string
+	Bar          string
+	Blah         int `env:"A_SPECIAL_BLAH"`
+	ABool        bool
+	NotThere     int `env:"-"`
+	HTTPServer   string
+	IntPointer   *int
+	FloatPointer *float64
+    // ...
+}
+```
+
+Turns into
+```shell
+TST_FOO="a\nfoo with \" quotes and \\ and '"
+TST_BAR="42str"
+TST_A_SPECIAL_BLAH="42"
+TST_A_BOOL=true
+TST_HTTP_SERVER="http://localhost:8080"
+TST_INT_POINTER="199"
+```
+
+Using
+```go
+struct2env.ToShellWithPrefix("TST_", struct2env.StructToEnvVars(foo))
+```