Add an npm package output

.bazelrc

@@ -0,0 +1 @@
+build:release -c opt --stamp --workspace_status_command="$PWD/stamp.sh"

BUILD

@@ -1,5 +1,6 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
 load("@bazel_gazelle//:def.bzl", "gazelle")
+load("@build_bazel_rules_nodejs//:index.bzl", "pkg_npm")
 
 # gazelle:prefix github.com/bazelbuild/bazelisk
 gazelle(name = "gazelle")
@@ -54,3 +55,48 @@ go_binary(
     embed = [":go_default_library"],
     visibility = ["//visibility:public"],
 )
+
+
+go_binary(
+    name = "bazelisk-darwin",
+    out = "bazelisk-darwin_amd64",
+    embed = [":go_default_library"],
+    goarch = "amd64",
+    goos = "darwin",
+    pure = "on",
+    visibility = ["//visibility:public"],
+)
+
+go_binary(
+    name = "bazelisk-linux",
+    out = "bazelisk-linux_amd64",
+    embed = [":go_default_library"],
+    goarch = "amd64",
+    goos = "linux",
+    pure = "on",
+    visibility = ["//visibility:public"],
+)
+
+go_binary(
+    name = "bazelisk-windows",
+    out = "bazelisk-windows_amd64.exe",
+    embed = [":go_default_library"],
+    goarch = "amd64",
+    goos = "windows",
+    pure = "on",
+    visibility = ["//visibility:public"],
+)
+
+pkg_npm(
+    name = "npm_package",
+    srcs = [
+        "LICENSE",
+        "package.json",
+        "bazelisk.js",
+    ],
+    deps = [
+        ":bazelisk-darwin",
+        ":bazelisk-linux",
+        ":bazelisk-windows",
+    ],
+)

WORKSPACE

@@ -41,3 +41,13 @@ go_repository(
     sum = "h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=",
     version = "v1.1.0",
 )
+
+# We don't use any nodejs but this includes a rule for publishing releases to npm
+http_archive(
+    name = "build_bazel_rules_nodejs",
+    patches = ["//:rules_nodejs.pr1591.patch"],
+    sha256 = "ecaa54955b314b5e33948bd8f39e35c35ee89e905d8de1c03868100293510573",
+    urls = ["https://github.com/bazelbuild/rules_nodejs/releases/download/1.2.1/rules_nodejs-1.2.1.tar.gz"],
+)
+load("@build_bazel_rules_nodejs//:index.bzl", "node_repositories")
+node_repositories()

bazelisk.js

@@ -0,0 +1,73 @@
+#!/usr/bin/env node
+// Copyright 2020 The Bazel Authors. All rights reserved.
+//
+// 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.
+'use strict';
+
+// This package inspired by
+// https://github.com/angular/clang-format/blob/master/index.js
+const os = require('os');
+const path = require('path');
+const spawn = require('child_process').spawn;
+
+function getNativeBinary() {
+  const arch = {
+    'x64' : 'amd64',
+  }[os.arch()];
+  // Filter the platform based on the platforms that are build/included.
+  const platform = {
+    'darwin' : 'darwin',
+    'linux' : 'linux',
+    'win32' : 'windows',
+  }[os.platform()];
+  const extension = {
+    'darwin' : '',
+    'linux' : '',
+    'win32' : '.exe',
+  }[os.platform()];
+
+  if (arch == undefined || platform == undefined) {
+    console.error(`FATAL: Your platform/architecture combination ${
+        os.platform()} - ${os.arch()} is not yet supported.
+    You may need to compile Bazelisk yourself, or use the Python version.
+    See instructions at https://github.com/bazelbuild/bazelisk/blob/master/README.md.`);
+    return Promise.resolve(1);
+  }
+
+  const binary =
+      path.join(__dirname, `bazelisk-${platform}_${arch}${extension}`);
+  return binary;
+}
+
+function main(args) {
+  const binary = getNativeBinary();
+  const ps = spawn(binary, args, {stdio : 'inherit'});
+
+  function shutdown() {
+    ps.kill("SIGTERM")
+    process.exit();
+  }
+
+  process.on("SIGINT", shutdown);
+  process.on("SIGTERM", shutdown);
+
+  ps.on('close', e => process.exitCode = e);
+}
+
+if (require.main === module) {
+  main(process.argv.slice(2));
+}
+
+module.exports = {
+  getNativeBinary,
+};

build.sh

@@ -22,10 +22,7 @@ mkdir bin
 
 go build
 for platform in darwin linux windows; do
-    ./bazelisk build \
-        -c opt \
-        --stamp \
-        --workspace_status_command="$PWD/stamp.sh" \
+    ./bazelisk build --config=release \
         --platforms=@io_bazel_rules_go//go/toolchain:${platform}_amd64 \
         //:bazelisk
     if [[ $platform == windows ]]; then
@@ -44,3 +41,9 @@ rm -f bazelisk
 ### Print some information about the generated binaries.
 ls -lh bin/*
 file bin/*
+
+# Non-googlers: you should run this script with NPM_REGISTRY=https://registry.npmjs.org
+readonly REGISTRY=${NPM_REGISTRY:-https://wombat-dressing-room.appspot.com}
+# Googlers: you should npm login using the go/npm-publish service:
+# $ npm login --registry https://wombat-dressing-room.appspot.com
+./bazelisk run --config=release //:npm_package.publish -- --access=public --tag latest --registry $REGISTRY

package.json

@@ -0,0 +1,19 @@
+{
+    "name": "@bazel/bazelisk",
+    "description": "A user-friendly launcher for Bazel",
+    "version": "0.0.0-PLACEHOLDER",
+    "license": "Apache-2.0",
+    "bin": {
+        "bazelisk": "bazelisk.js"
+    },
+    "keywords": [
+        "bazel"
+    ],
+    "repository": {
+        "type": "git",
+        "url": "https://github.com/bazelbuild/bazelisk.git"
+    },
+    "bugs": {
+        "url": "https://github.com/bazelbuild/bazelisk/issues"
+    }
+}

rules_nodejs.pr1591.patch

@@ -0,0 +1,13 @@
+diff internal/pkg_npm/packager.js internal/pkg_npm/packager.js
+index ac41b585..48167a19 100644
+--- internal/pkg_npm/packager.js
++++ internal/pkg_npm/packager.js
+@@ -89,7 +89,7 @@ function main(args) {
+                              .find(s => s.startsWith('BUILD_SCM_VERSION'));
+       // Don't assume BUILD_SCM_VERSION exists
+       if (versionTag) {
+-        version = versionTag.split(' ')[1].trim();
++        version = versionTag.split(' ')[1].replace(/^v/, '').trim();
+       }
+     }
+     substitutions.push([new RegExp(replaceWithVersion, 'g'), version]);

stamp.sh

@@ -7,3 +7,5 @@ CURRENT_TAG=$(git tag -l --points-at HEAD | head -n1)
 CURRENT_COMMIT=$(git rev-parse HEAD)
 
 echo "STABLE_VERSION ${CURRENT_TAG:-$CURRENT_COMMIT}"
+# rules_nodejs expects to read from volatile-status.txt
+echo "BUILD_SCM_VERSION ${CURRENT_TAG:-$CURRENT_COMMIT}"