feat: ported action definition from setup-terraform

Signed-off-by: Dmitry Kisler <admin@dkisler.com>

.github/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: "npm"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/workflows/continuous-integration.yml

@@ -0,0 +1,15 @@
+name: 'Continuous Integration'
+
+on:
+  push:
+    branches:
+    - main
+  pull_request:
+
+jobs:
+  check-dist:
+    name: Check dist/ directory
+    uses: actions/reusable-workflows/.github/workflows/check-dist.yml@a8533f184b279cfc1b2dd6a96ed2f097ccf81189
+  test:
+    name: Test
+    uses: actions/reusable-workflows/.github/workflows/basic-validation.yml@a8533f184b279cfc1b2dd6a96ed2f097ccf81189

.github/workflows/data/local/main.tf

@@ -0,0 +1,5 @@
+resource "null_resource" "null" {
+  triggers = {
+    value = timestamp()
+  }
+}

.github/workflows/setup-terraform.yml

@@ -0,0 +1,316 @@
+name: 'Setup OpenTofu'
+
+on:
+  push:
+    branches:
+    - main
+  pull_request:
+  # TODO: remove after manual tests
+  workflow_dispatch:
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  tofu-versions:
+    name: 'OpenTofu Versions'
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+        # TODO: add move versions to test when the feature is added
+        tofu-versions: [latest]
+    steps:
+    - name: Checkout
+      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+
+    - name: Setup OpenTofu - ${{ matrix['tofu-versions'] }}
+      uses: ./
+      with:
+        tofu_version: ${{ matrix['tofu-versions'] }}
+
+    - name: Validate OpenTofu Version - ${{ matrix['tofu-versions'] }}
+      if: ${{ matrix['tofu-versions'] != 'latest' }}
+      run: tofu version | grep ${{ matrix['tofu-versions']}}
+
+    - name: Validate OpenTofu Version - ${{ matrix['tofu-versions'] }}
+      if: ${{ matrix['tofu-versions'] == 'latest' }}
+      run: tofu version | grep 'OpenTofu v'
+
+  tofu-versions-no-wrapper:
+    name: 'OpenTofu Versions No Wrapper'
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+        # TODO: add more versions to test when the semver feature is implemented
+        tofu-versions: [latest]
+    steps:
+    - name: Checkout
+      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+
+    - name: Setup OpenTofu (no wrapper) - ${{ matrix['tofu-versions'] }}
+      uses: ./
+      with:
+        tofu_version: ${{ matrix['tofu-versions'] }}
+        tofu_wrapper: false
+
+    - name: Validate OpenTofu Version - ${{ matrix['tofu-versions'] }}
+      if: ${{ matrix['tofu-versions'] != 'latest' }}
+      run: tofu version | grep ${{ matrix['tofu-versions']}}
+
+    - name: Validate OpenTofu Version - ${{ matrix['tofu-versions'] }}
+      if: ${{ matrix['tofu-versions'] == 'latest' }}
+      run: tofu version | grep 'OpenTofu v'
+
+# TODO: uncomment when the semver feature is implemented
+#  tofu-versions-constraints:
+#    name: 'OpenTofu Versions Constraints'
+#    runs-on: ${{ matrix.os }}
+#    strategy:
+#      matrix:
+#        os: [ubuntu-latest, windows-latest, macos-latest]
+#        tofu-versions: [~0.12, 0.12.x, <0.13.0]
+#    steps:
+#    - name: Checkout
+#      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+#
+#    - name: Setup OpenTofu - ${{ matrix['tofu-versions'] }}
+#      uses: ./
+#      with:
+#        tofu_version: ${{ matrix['tofu-versions'] }}
+#
+#    - name: Validate OpenTofu Version - ${{ matrix['tofu-versions'] }}
+#      run: tofu version | grep 'OpenTofu v0\.12'
+
+# TODO: uncomment when the semver feature is implemented
+#  tofu-versions-constraints-no-wrapper:
+#    name: 'OpenTofu Versions Constraints No Wrapper'
+#    runs-on: ${{ matrix.os }}
+#    strategy:
+#      matrix:
+#        os: [ubuntu-latest, windows-latest, macos-latest]
+#        tofu-versions: [~0.12, 0.12.x, <0.13.0]
+#    steps:
+#    - name: Checkout
+#      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+#
+#    - name: Setup OpenTofu (no wrapper) - ${{ matrix['tofu-versions'] }}
+#      uses: ./
+#      with:
+#        tofu_version: ${{ matrix['tofu-versions'] }}
+#        tofu_wrapper: false
+#
+#    - name: Validate OpenTofu Version - ${{ matrix['tofu-versions'] }}
+#      run: tofu version | grep 'OpenTofu v0\.12'
+
+  tofu-credentials-cloud:
+    name: 'OpenTofu Cloud Credentials'
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    env:
+      TF_CLOUD_API_TOKEN: 'XXXXXXXXXXXXXX.atlasv1.XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
+    steps:
+    - name: Checkout
+      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+
+    - name: Setup OpenTofu
+      uses: ./
+      with:
+        cli_config_credentials_token: ${{ env.TF_CLOUD_API_TOKEN }}
+
+    - name: Validate OpenTofu Credentials (Windows)
+      if: runner.os == 'Windows'
+      run: |
+        cat ${APPDATA}/terraform.rc | grep 'credentials "app.terraform.io"'
+        cat ${APPDATA}/terraform.rc | grep 'token = "${{ env.TF_CLOUD_API_TOKEN }}"'
+
+    - name: Validate Teraform Credentials (Linux & macOS)
+      if: runner.os != 'Windows'
+      run: |
+        cat ${HOME}/.terraformrc | grep 'credentials "app.terraform.io"'
+        cat ${HOME}/.terraformrc | grep 'token = "${{ env.TF_CLOUD_API_TOKEN }}"'
+
+  tofu-credentials-enterprise:
+    name: 'OpenTofu Enterprise Credentials'
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    env:
+      TF_CLOUD_API_TOKEN: 'XXXXXXXXXXXXXX.atlasv1.XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
+    steps:
+    - name: Checkout
+      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+
+    - name: Setup OpenTofu
+      uses: ./
+      with:
+        cli_config_credentials_hostname: 'tofu.example.com'
+        cli_config_credentials_token: ${{ env.TF_CLOUD_API_TOKEN }}
+
+    - name: Validate OpenTofu Credentials (Windows)
+      if: runner.os == 'Windows'
+      run: |
+        cat ${APPDATA}/terraform.rc | grep 'credentials "tofu.example.com"'
+        cat ${APPDATA}/terraform.rc | grep 'token = "${{ env.TF_CLOUD_API_TOKEN }}"'
+
+    - name: Validate Teraform Credentials (Linux & macOS)
+      if: runner.os != 'Windows'
+      run: |
+        cat ${HOME}/.terraformrc | grep 'credentials "tofu.example.com"'
+        cat ${HOME}/.terraformrc | grep 'token = "${{ env.TF_CLOUD_API_TOKEN }}"'
+
+  tofu-credentials-none:
+    name: 'OpenTofu No Credentials'
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    steps:
+    - name: Checkout
+      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+
+    - name: Setup OpenTofu
+      uses: ./
+
+    - name: Validate OpenTofu Credentials (Windows)
+      if: runner.os == 'Windows'
+      run: |
+        [[ -f ${APPDATA}/terraform.rc ]] || exit 0
+
+    - name: Validate Teraform Credentials (Linux & macOS)
+      if: runner.os != 'Windows'
+      run: |
+        [[ -f ${HOME}/.terraformrc ]] || exit 0
+
+  tofu-arguments:
+    name: 'OpenTofu Arguments'
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    steps:
+    - name: Checkout
+      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+
+    - name: Setup OpenTofu
+      uses: ./
+
+    - name: Check No Arguments
+      run: tofu || exit 0
+
+    - name: Check Single Argument
+      run: tofu help || exit 0
+
+    - name: Check Single Argument Hyphen
+      run: tofu -help
+
+    - name: Check Single Argument Double Hyphen
+      run: tofu --help
+
+    - name: Check Single Argument Subcommand
+      run: tofu fmt -check
+
+    - name: Check Multiple Arguments Subcommand
+      run: tofu fmt -check -list=true -no-color
+
+  tofu-arguments-no-wrapper:
+    name: 'OpenTofu Arguments No Wrapper'
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    steps:
+    - name: Checkout
+      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+
+    - name: Setup OpenTofu
+      uses: ./
+      with:
+        tofu_wrapper: false
+
+    - name: Check No Arguments
+      run: tofu || exit 0
+
+    - name: Check Single Argument
+      run: tofu help || exit 0
+
+    - name: Check Single Argument Hyphen
+      run: tofu -help
+
+    - name: Check Single Argument Double Hyphen
+      run: tofu --help
+
+    - name: Check Single Argument Subcommand
+      run: tofu fmt -check
+
+    - name: Check Multiple Arguments Subcommand
+      run: tofu fmt -check -list=true -no-color
+
+  tofu-run-local:
+    name: 'OpenTofu Run Local'
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    defaults:
+      run:
+        working-directory: ./.github/workflows/data/local
+    steps:
+    - name: Checkout
+      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+
+    - name: Setup OpenTofu
+      uses: ./
+
+    - name: OpenTofu Init
+      shell: bash
+      run: tofu init
+
+    - name: OpenTofu Format
+      shell: bash
+      run: tofu fmt -check
+
+    - name: OpenTofu Plan
+      id: plan
+      shell: bash
+      run: tofu plan
+
+    - name: Print OpenTofu Plan
+      shell: bash
+      run: echo "${{ steps.plan.outputs.stdout }}"
+
+  tofu-run-local-no-wrapper:
+    name: 'OpenTofu Run Local No Wrapper'
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    defaults:
+      run:
+        working-directory: ./.github/workflows/data/local
+    steps:
+    - name: Checkout
+      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+
+    - name: Setup OpenTofu
+      uses: ./
+      with:
+        tofu_wrapper: false
+
+    - name: OpenTofu Init
+      shell: bash
+      run: tofu init
+
+    - name: OpenTofu Format
+      shell: bash
+      run: tofu fmt -check
+
+    - name: OpenTofu Plan
+      id: plan
+      shell: bash
+      run: tofu plan

.gitignore

@@ -0,0 +1,72 @@
+node_modules/
+
+# Editors
+.vscode
+
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (https://nodejs.org/api/addons.html)
+build/Release
+
+# Other Dependency directories
+jspm_packages/
+
+# TypeScript v1 declaration files
+typings/
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variables file
+.env
+
+# next.js build output
+.next
+
+# ./wrapper/dist gets included in top-level ./dist
+wrapper/dist
+
+# Jetbrains IDEs
+.idea/
+.iml

.husky/.gitignore

@@ -0,0 +1 @@
+_

.husky/pre-commit

@@ -0,0 +1,4 @@
+#!/bin/sh
+. "$(dirname "$0")/_/husky.sh"
+
+npm run build && git add dist/

README.md

@@ -2,9 +2,9 @@
 
 The `opentofu/setup-opentofu` action sets up OpenTofu CLI in your GitHub Actions workflow by:
 
-- [ ] Downloading the latest version of OpenTofu CLI and adding it to the `PATH`.
+- Downloading the latest version of OpenTofu CLI and adding it to the `PATH`.
-- [ ] Configuring the [CLI configuration file](https://www.terraform.io/docs/commands/cli-config.html) with a Terraform Cloud/Enterprise hostname and API token.
+- Configuring the [CLI configuration file](https://www.terraform.io/docs/commands/cli-config.html) with a Terraform Cloud/Enterprise hostname and API token.
-- [ ] Installing a wrapper script to wrap subsequent calls of the `tofu` binary and expose its STDOUT, STDERR, and exit code as outputs named `stdout`, `stderr`, and `exitcode` respectively. (This can be optionally skipped if subsequent steps in the same job do not need to access the results of
+- Installing a wrapper script to wrap subsequent calls of the `tofu` binary and expose its STDOUT, STDERR, and exit code as outputs named `stdout`, `stderr`, and `exitcode` respectively. (This can be optionally skipped if subsequent steps in the same job do not need to access the results of
   OpenTofu commands.)
 
 After you've used the action, subsequent steps in the same job can run arbitrary OpenTofu commands using [the GitHub Actions `run` syntax](https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idstepsrun). This allows most OpenTofu commands to work exactly

index.js

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+const core = require('@actions/core');
+
+const setup = require('./lib/setup-tofu');
+
+(async () => {
+  try {
+    await setup();
+  } catch (error) {
+    core.setFailed(error.message);
+  }
+})();

lib/releases.js

@@ -0,0 +1,62 @@
+/**
+ * Copyright (c) OpenTofu
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+class Build {
+  constructor (name, url) {
+    this.name = name;
+    this.url = url;
+  }
+}
+
+class Release {
+  constructor (releaseMeta) {
+    this.version = releaseMeta.tag_name.replace('v', '');
+    this.builds = releaseMeta.assets.map(asset => new Build(asset.name, asset.browser_download_url));
+  }
+
+  getBuild (platform, arch) {
+    const requiredName = `tofu_${this.version}_${platform}_${arch}.zip`;
+    return this.builds.find(build => build.name === requiredName);
+  }
+}
+
+/**
+ * Fetches the top 30 releases sorted in desc order.
+ *
+ */
+async function fetchReleases () {
+  const url = 'https://api.github.com/repos/opentofu/opentofu/releases';
+
+  const resp = await fetch(url, {
+    headers: {
+      Accept: 'application/vnd.github+json',
+      'X-GitHub-Api-Version': '2022-11-28'
+    }
+  });
+
+  if (!resp.ok) {
+    throw Error('failed fetching releases');
+  }
+
+  const releasesMeta = await resp.json();
+
+  return releasesMeta.map(releaseMeta => new Release(releaseMeta));
+}
+
+/**
+ * Fetches the release given the version.
+ *
+ * @param {string} version: Release version.
+ */
+async function getRelease (version) {
+  const releases = await fetchReleases();
+  return releases.find(release => release.version === version);
+}
+
+// Note that the export is defined as adaptor to replace hashicorp/js-releases
+// See: https://github.com/hashicorp/setup-terraform/blob/e192cfcbae6c6ed207c277ed7624131996c9bf13/lib/setup-terraform.js#L15
+module.exports = {
+  getRelease
+};

lib/setup-tofu.js

@@ -0,0 +1,170 @@
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * Copyright (c) OpenTofu
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+// Node.js core
+const fs = require('fs').promises;
+const os = require('os');
+const path = require('path');
+
+// External
+const core = require('@actions/core');
+const tc = require('@actions/tool-cache');
+const io = require('@actions/io');
+const releases = require('./releases');
+
+// arch in [arm, x32, x64...] (https://nodejs.org/api/os.html#os_os_arch)
+// return value in [amd64, 386, arm]
+function mapArch (arch) {
+  const mappings = {
+    x32: '386',
+    x64: 'amd64'
+  };
+  return mappings[arch] || arch;
+}
+
+// os in [darwin, linux, win32...] (https://nodejs.org/api/os.html#os_os_platform)
+// return value in [darwin, linux, windows]
+function mapOS (os) {
+  const mappings = {
+    win32: 'windows'
+  };
+  return mappings[os] || os;
+}
+
+async function downloadCLI (url) {
+  core.debug(`Downloading OpenTofu CLI from ${url}`);
+  const pathToCLIZip = await tc.downloadTool(url);
+
+  let pathToCLI = '';
+
+  core.debug('Extracting OpenTofu CLI zip file');
+  if (os.platform().startsWith('win')) {
+    core.debug(`OpenTofu CLI Download Path is ${pathToCLIZip}`);
+    const fixedPathToCLIZip = `${pathToCLIZip}.zip`;
+    io.mv(pathToCLIZip, fixedPathToCLIZip);
+    core.debug(`Moved download to ${fixedPathToCLIZip}`);
+    pathToCLI = await tc.extractZip(fixedPathToCLIZip);
+  } else {
+    pathToCLI = await tc.extractZip(pathToCLIZip);
+  }
+
+  core.debug(`OpenTofu CLI path is ${pathToCLI}.`);
+
+  if (!pathToCLIZip || !pathToCLI) {
+    throw new Error(`Unable to download OpenTofu from ${url}`);
+  }
+
+  return pathToCLI;
+}
+
+async function installWrapper (pathToCLI) {
+  let source, target;
+
+  // If we're on Windows, then the executable ends with .exe
+  const exeSuffix = os.platform().startsWith('win') ? '.exe' : '';
+
+  // Rename tofu(.exe) to tofu-bin(.exe)
+  try {
+    source = [pathToCLI, `tofu${exeSuffix}`].join(path.sep);
+    target = [pathToCLI, `tofu-bin${exeSuffix}`].join(path.sep);
+    core.debug(`Moving ${source} to ${target}.`);
+    await io.mv(source, target);
+  } catch (e) {
+    core.error(`Unable to move ${source} to ${target}.`);
+    throw e;
+  }
+
+  // Install our wrapper as tofu
+  try {
+    source = path.resolve([__dirname, '..', 'wrapper', 'dist', 'index.js'].join(path.sep));
+    target = [pathToCLI, 'tofu'].join(path.sep);
+    core.debug(`Copying ${source} to ${target}.`);
+    await io.cp(source, target);
+  } catch (e) {
+    core.error(`Unable to copy ${source} to ${target}.`);
+    throw e;
+  }
+
+  // Export a new environment variable, so our wrapper can locate the binary
+  core.exportVariable('TOFU_CLI_PATH', pathToCLI);
+}
+
+// Add credentials to CLI Configuration File
+// https://www.tofu.io/docs/commands/cli-config.html
+async function addCredentials (credentialsHostname, credentialsToken, osPlat) {
+  // format HCL block
+  // eslint-disable
+  const creds = `
+credentials "${credentialsHostname}" {
+  token = "${credentialsToken}"
+}`.trim();
+  // eslint-enable
+
+  // default to OS-specific path
+  let credsFile = osPlat === 'win32'
+    ? `${process.env.APPDATA}/terraform.rc`
+    : `${process.env.HOME}/.terraformrc`;
+
+  // override with TF_CLI_CONFIG_FILE environment variable
+  credsFile = process.env.TF_CLI_CONFIG_FILE ? process.env.TF_CLI_CONFIG_FILE : credsFile;
+
+  // get containing folder
+  const credsFolder = path.dirname(credsFile);
+
+  core.debug(`Creating ${credsFolder}`);
+  await io.mkdirP(credsFolder);
+
+  core.debug(`Adding credentials to ${credsFile}`);
+  await fs.writeFile(credsFile, creds);
+}
+
+async function run () {
+  try {
+    // Gather GitHub Actions inputs
+    const version = '1.6.0-alpha1';
+    // TODO: allow dynamic version selection once logic is ready
+    // const version = core.getInput('tofu_version');
+    const credentialsHostname = core.getInput('cli_config_credentials_hostname');
+    const credentialsToken = core.getInput('cli_config_credentials_token');
+    const wrapper = core.getInput('tofu_wrapper') === 'true';
+
+    // Gather OS details
+    const osPlatform = os.platform();
+    const osArch = os.arch();
+
+    core.debug(`Finding releases for OpenTofu version ${version}`);
+    const release = await releases.getRelease(version);
+    const platform = mapOS(osPlatform);
+    const arch = mapArch(osArch);
+    core.debug(`Getting build for OpenTofu version ${release.version}: ${platform} ${arch}`);
+    const build = release.getBuild(platform, arch);
+    if (!build) {
+      throw new Error(`OpenTofu version ${version} not available for ${platform} and ${arch}`);
+    }
+
+    // Download requested version
+    const pathToCLI = await downloadCLI(build.url);
+
+    // Install our wrapper
+    if (wrapper) {
+      await installWrapper(pathToCLI);
+    }
+
+    // Add to path
+    core.addPath(pathToCLI);
+
+    // Add credentials to file if they are provided
+    if (credentialsHostname && credentialsToken) {
+      await addCredentials(credentialsHostname, credentialsToken, osPlatform);
+    }
+    return release;
+  } catch (error) {
+    core.error(error);
+    throw error;
+  }
+}
+
+module.exports = run;

package.json

@@ -0,0 +1,40 @@
+{
+  "name": "setup-opentofu",
+  "version": "0.0.1",
+  "description": "Setup OpenTofu CLI for GitHub Actions",
+  "license": "MPL-2.0",
+  "publisher": "OpenTofu",
+  "main": "index.js",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/opentofu/setup-opentofu.git"
+  },
+  "scripts": {
+    "test": "semistandard --env jest && jest --coverage",
+    "lint": "semistandard --env jest --fix",
+    "build": "ncc build wrapper/tofu.js --out wrapper/dist && ncc build index.js --out dist",
+    "prepare": "husky install",
+    "format-check": "echo \"unimplemented for actions/reusable-workflows basic-validation\""
+  },
+  "keywords": [],
+  "author": "",
+  "dependencies": {
+    "@actions/core": "^1.10.1",
+    "@actions/exec": "^1.1.1",
+    "@actions/github": "^5.1.1",
+    "@actions/io": "^1.1.3",
+    "@actions/tool-cache": "^2.0.1"
+  },
+  "devDependencies": {
+    "@vercel/ncc": "^0.38.0",
+    "husky": "^8.0.3",
+    "jest": "^29.7.0",
+    "nock": "^13.3.3",
+    "semistandard": "^17.0.0"
+  },
+  "semistandard": {
+    "ignore": [
+      "**/dist/**"
+    ]
+  }
+}

wrapper/lib/output-listener.js

@@ -0,0 +1,41 @@
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+/**
+ * Acts as a listener for @actions/exec, by capturing STDOUT and STDERR
+ * streams, and exposing them via a contents attribute.
+ *
+ * @example
+ * // Instantiate a new listener
+ * const listener = new OutputListener();
+ * // Register listener against STDOUT stream
+ * await exec.exec('ls', ['-ltr'], {
+ *  listeners: {
+ *    stdout: listener.listener
+ *  }
+ * });
+ * // Log out STDOUT contents
+ * console.log(listener.contents);
+ */
+class OutputListener {
+  constructor () {
+    this._buff = [];
+  }
+
+  get listener () {
+    const listen = function listen (data) {
+      this._buff.push(data);
+    };
+    return listen.bind(this);
+  }
+
+  get contents () {
+    return this._buff
+      .map(chunk => chunk.toString())
+      .join('');
+  }
+}
+
+module.exports = OutputListener;

wrapper/lib/tofu-bin.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+const os = require('os');
+const path = require('path');
+
+module.exports = (() => {
+  // If we're on Windows, then the executable ends with .exe
+  const exeSuffix = os.platform().startsWith('win') ? '.exe' : '';
+
+  return [process.env.TOFU_CLI_PATH, `tofu-bin${exeSuffix}`].join(path.sep);
+})();

wrapper/test/output-listener.test.js

@@ -0,0 +1,17 @@
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+const OutputListener = require('../lib/output-listener');
+
+describe('output-listener', () => {
+  it('receives and exposes data', () => {
+    const listener = new OutputListener();
+    const listen = listener.listener;
+    listen(Buffer.from('foo'));
+    listen(Buffer.from('bar'));
+    listen(Buffer.from('baz'));
+    expect(listener.contents).toEqual('foobarbaz');
+  });
+});

wrapper/tofu.js

@@ -0,0 +1,59 @@
+#!/usr/bin/env node
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+const io = require('@actions/io');
+const core = require('@actions/core');
+const { exec } = require('@actions/exec');
+
+const OutputListener = require('./lib/output-listener');
+const pathToCLI = require('./lib/tofu-bin');
+
+async function checkTofu () {
+  // Setting check to `true` will cause `which` to throw if tofu isn't found
+  const check = true;
+  return io.which(pathToCLI, check);
+}
+
+(async () => {
+  // This will fail if tofu isn't found, which is what we want
+  await checkTofu();
+
+  // Create listeners to receive output (in memory) as well
+  const stdout = new OutputListener();
+  const stderr = new OutputListener();
+  const listeners = {
+    stdout: stdout.listener,
+    stderr: stderr.listener
+  };
+
+  // Execute tofu and capture output
+  const args = process.argv.slice(2);
+  const options = {
+    listeners,
+    ignoreReturnCode: true
+  };
+  const exitCode = await exec(pathToCLI, args, options);
+  core.debug(`OpenTofu exited with code ${exitCode}.`);
+  core.debug(`stdout: ${stdout.contents}`);
+  core.debug(`stderr: ${stderr.contents}`);
+  core.debug(`exitcode: ${exitCode}`);
+
+  // Set outputs, result, exitcode, and stderr
+  core.setOutput('stdout', stdout.contents);
+  core.setOutput('stderr', stderr.contents);
+  core.setOutput('exitcode', exitCode.toString(10));
+
+  if (exitCode === 0 || exitCode === 2) {
+    // A exitCode of 0 is considered a success
+    // An exitCode of 2 may be returned when the '-detailed-exitcode' option
+    // is passed to plan. This denotes Success with non-empty
+    // diff (changes present).
+    return;
+  }
+
+  // A non-zero exitCode is considered an error
+  core.setFailed(`OpenTofu exited with code ${exitCode}.`);
+})();