Randomize SSH auth socket, kill agent to support non-ephemeral, self hosted runners (@thommyhh, #27)

Thanks to @thommyhh for this contribution!

Unless the `SSH_AUTH_SOCK` is configured explicitly, this change will make the SSH agent use a random file name for the socket. That way, multiple, concurrent SSH agents can be used on non-ephemeral, self-hosted runners.

A new post-action step will automatically clean up the running agent at the end of a job.

Be aware of the possible security implications: Two jobs running on the same runner might be able to access each other's socket and thus access repositories and/or hosts.

README.md

@@ -57,6 +57,11 @@ The `ssh-agent` will load all of the keys and try each one in order when establi
 There's one **caveat**, though: SSH servers may abort the connection attempt after a number of mismatching keys have been presented. So if, for example, you have
 six different keys loaded into the `ssh-agent`, but the server aborts after five unknown keys, the last key (which might be the right one) will never even be tried.
 
+## Exported variables
+The action exports `SSH_AUTH_SOCK` and `SSH_AGENT_PID` through the Github Actions core module.
+The `$SSH_AUTH_SOCK` is used by several applications like git or rsync to connect to the SSH authentication agent.
+The `$SSH_AGENT_PID` contains the process id of the agent. This is used to kill the agent in post job action.
+
 ## Known issues and limitations
 
 ### Currently OS X and Linux only
@@ -116,7 +121,7 @@ As a note to my future self, in order to work on this repo:
 * Run `npm install` to fetch dependencies
 * _hack hack hack_
 * `node index.js`. Inputs are passed through `INPUT_` env vars with their names uppercased. Use `env "INPUT_SSH-PRIVATE-KEY=\`cat file\`" node index.js` for this action.
-* Run `./node_modules/.bin/ncc build index.js` to update `dist/index.js`, which is the file actually run
+* Run `npm run build` to update `dist/*`, which holds the files actually run
 * Read https://help.github.com/en/articles/creating-a-javascript-action if unsure.
 * Maybe update the README example when publishing a new version.
 

action.yml

@@ -6,10 +6,10 @@ inputs:
         required: true
     ssh-auth-sock:
         description: 'Where to place the SSH Agent auth socket'
-        default: /tmp/ssh-auth.sock
 runs:
     using: 'node12'
     main: 'dist/index.js'
+    post: 'dist/cleanup.js'
 branding:
     icon: loader
     color: 'yellow'

cleanup.js

@@ -0,0 +1,10 @@
+const core = require('@actions/core')
+const { execSync } = require('child_process')
+
+try {
+    // Kill the started SSH agent
+    console.log('Stopping SSH agent')
+    execSync('kill ${SSH_AGENT_PID}', { stdio: 'inherit' })
+} catch (error) {
+    core.setFailed(error.message)
+}

dist/cleanup.js

@@ -0,0 +1,332 @@
+module.exports =
+/******/ (function(modules, runtime) { // webpackBootstrap
+/******/ 	"use strict";
+/******/ 	// The module cache
+/******/ 	var installedModules = {};
+/******/
+/******/ 	// The require function
+/******/ 	function __webpack_require__(moduleId) {
+/******/
+/******/ 		// Check if module is in cache
+/******/ 		if(installedModules[moduleId]) {
+/******/ 			return installedModules[moduleId].exports;
+/******/ 		}
+/******/ 		// Create a new module (and put it into the cache)
+/******/ 		var module = installedModules[moduleId] = {
+/******/ 			i: moduleId,
+/******/ 			l: false,
+/******/ 			exports: {}
+/******/ 		};
+/******/
+/******/ 		// Execute the module function
+/******/ 		modules[moduleId].call(module.exports, module, module.exports, __webpack_require__);
+/******/
+/******/ 		// Flag the module as loaded
+/******/ 		module.l = true;
+/******/
+/******/ 		// Return the exports of the module
+/******/ 		return module.exports;
+/******/ 	}
+/******/
+/******/
+/******/ 	__webpack_require__.ab = __dirname + "/";
+/******/
+/******/ 	// the startup function
+/******/ 	function startup() {
+/******/ 		// Load entry module and return exports
+/******/ 		return __webpack_require__(175);
+/******/ 	};
+/******/
+/******/ 	// run startup
+/******/ 	return startup();
+/******/ })
+/************************************************************************/
+/******/ ({
+
+/***/ 87:
+/***/ (function(module) {
+
+module.exports = require("os");
+
+/***/ }),
+
+/***/ 129:
+/***/ (function(module) {
+
+module.exports = require("child_process");
+
+/***/ }),
+
+/***/ 175:
+/***/ (function(__unusedmodule, __unusedexports, __webpack_require__) {
+
+const core = __webpack_require__(470)
+const { execSync } = __webpack_require__(129)
+
+try {
+    // Kill the started SSH agent
+    console.log('Stopping SSH agent')
+    execSync('kill ${SSH_AGENT_PID}', { stdio: 'inherit' })
+} catch (error) {
+    core.setFailed(error.message)
+}
+
+
+/***/ }),
+
+/***/ 431:
+/***/ (function(__unusedmodule, exports, __webpack_require__) {
+
+"use strict";
+
+Object.defineProperty(exports, "__esModule", { value: true });
+const os = __webpack_require__(87);
+/**
+ * Commands
+ *
+ * Command Format:
+ *   ##[name key=value;key=value]message
+ *
+ * Examples:
+ *   ##[warning]This is the user warning message
+ *   ##[set-secret name=mypassword]definitelyNotAPassword!
+ */
+function issueCommand(command, properties, message) {
+    const cmd = new Command(command, properties, message);
+    process.stdout.write(cmd.toString() + os.EOL);
+}
+exports.issueCommand = issueCommand;
+function issue(name, message = '') {
+    issueCommand(name, {}, message);
+}
+exports.issue = issue;
+const CMD_PREFIX = '##[';
+class Command {
+    constructor(command, properties, message) {
+        if (!command) {
+            command = 'missing.command';
+        }
+        this.command = command;
+        this.properties = properties;
+        this.message = message;
+    }
+    toString() {
+        let cmdStr = CMD_PREFIX + this.command;
+        if (this.properties && Object.keys(this.properties).length > 0) {
+            cmdStr += ' ';
+            for (const key in this.properties) {
+                if (this.properties.hasOwnProperty(key)) {
+                    const val = this.properties[key];
+                    if (val) {
+                        // safely append the val - avoid blowing up when attempting to
+                        // call .replace() if message is not a string for some reason
+                        cmdStr += `${key}=${escape(`${val || ''}`)};`;
+                    }
+                }
+            }
+        }
+        cmdStr += ']';
+        // safely append the message - avoid blowing up when attempting to
+        // call .replace() if message is not a string for some reason
+        const message = `${this.message || ''}`;
+        cmdStr += escapeData(message);
+        return cmdStr;
+    }
+}
+function escapeData(s) {
+    return s.replace(/\r/g, '%0D').replace(/\n/g, '%0A');
+}
+function escape(s) {
+    return s
+        .replace(/\r/g, '%0D')
+        .replace(/\n/g, '%0A')
+        .replace(/]/g, '%5D')
+        .replace(/;/g, '%3B');
+}
+//# sourceMappingURL=command.js.map
+
+/***/ }),
+
+/***/ 470:
+/***/ (function(__unusedmodule, exports, __webpack_require__) {
+
+"use strict";
+
+var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
+    function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
+    return new (P || (P = Promise))(function (resolve, reject) {
+        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
+        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
+        function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
+    });
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+const command_1 = __webpack_require__(431);
+const path = __webpack_require__(622);
+/**
+ * The code to exit an action
+ */
+var ExitCode;
+(function (ExitCode) {
+    /**
+     * A code indicating that the action was successful
+     */
+    ExitCode[ExitCode["Success"] = 0] = "Success";
+    /**
+     * A code indicating that the action was a failure
+     */
+    ExitCode[ExitCode["Failure"] = 1] = "Failure";
+})(ExitCode = exports.ExitCode || (exports.ExitCode = {}));
+//-----------------------------------------------------------------------
+// Variables
+//-----------------------------------------------------------------------
+/**
+ * sets env variable for this action and future actions in the job
+ * @param name the name of the variable to set
+ * @param val the value of the variable
+ */
+function exportVariable(name, val) {
+    process.env[name] = val;
+    command_1.issueCommand('set-env', { name }, val);
+}
+exports.exportVariable = exportVariable;
+/**
+ * exports the variable and registers a secret which will get masked from logs
+ * @param name the name of the variable to set
+ * @param val value of the secret
+ */
+function exportSecret(name, val) {
+    exportVariable(name, val);
+    // the runner will error with not implemented
+    // leaving the function but raising the error earlier
+    command_1.issueCommand('set-secret', {}, val);
+    throw new Error('Not implemented.');
+}
+exports.exportSecret = exportSecret;
+/**
+ * Prepends inputPath to the PATH (for this action and future actions)
+ * @param inputPath
+ */
+function addPath(inputPath) {
+    command_1.issueCommand('add-path', {}, inputPath);
+    process.env['PATH'] = `${inputPath}${path.delimiter}${process.env['PATH']}`;
+}
+exports.addPath = addPath;
+/**
+ * Gets the value of an input.  The value is also trimmed.
+ *
+ * @param     name     name of the input to get
+ * @param     options  optional. See InputOptions.
+ * @returns   string
+ */
+function getInput(name, options) {
+    const val = process.env[`INPUT_${name.replace(' ', '_').toUpperCase()}`] || '';
+    if (options && options.required && !val) {
+        throw new Error(`Input required and not supplied: ${name}`);
+    }
+    return val.trim();
+}
+exports.getInput = getInput;
+/**
+ * Sets the value of an output.
+ *
+ * @param     name     name of the output to set
+ * @param     value    value to store
+ */
+function setOutput(name, value) {
+    command_1.issueCommand('set-output', { name }, value);
+}
+exports.setOutput = setOutput;
+//-----------------------------------------------------------------------
+// Results
+//-----------------------------------------------------------------------
+/**
+ * Sets the action status to failed.
+ * When the action exits it will be with an exit code of 1
+ * @param message add error issue message
+ */
+function setFailed(message) {
+    process.exitCode = ExitCode.Failure;
+    error(message);
+}
+exports.setFailed = setFailed;
+//-----------------------------------------------------------------------
+// Logging Commands
+//-----------------------------------------------------------------------
+/**
+ * Writes debug message to user log
+ * @param message debug message
+ */
+function debug(message) {
+    command_1.issueCommand('debug', {}, message);
+}
+exports.debug = debug;
+/**
+ * Adds an error issue
+ * @param message error issue message
+ */
+function error(message) {
+    command_1.issue('error', message);
+}
+exports.error = error;
+/**
+ * Adds an warning issue
+ * @param message warning issue message
+ */
+function warning(message) {
+    command_1.issue('warning', message);
+}
+exports.warning = warning;
+/**
+ * Begin an output group.
+ *
+ * Output until the next `groupEnd` will be foldable in this group
+ *
+ * @param name The name of the output group
+ */
+function startGroup(name) {
+    command_1.issue('group', name);
+}
+exports.startGroup = startGroup;
+/**
+ * End an output group.
+ */
+function endGroup() {
+    command_1.issue('endgroup');
+}
+exports.endGroup = endGroup;
+/**
+ * Wrap an asynchronous function call in a group.
+ *
+ * Returns the same type as the function itself.
+ *
+ * @param name The name of the group
+ * @param fn The function to wrap in the group
+ */
+function group(name, fn) {
+    return __awaiter(this, void 0, void 0, function* () {
+        startGroup(name);
+        let result;
+        try {
+            result = yield fn();
+        }
+        finally {
+            endGroup();
+        }
+        return result;
+    });
+}
+exports.group = group;
+//# sourceMappingURL=core.js.map
+
+/***/ }),
+
+/***/ 622:
+/***/ (function(module) {
+
+module.exports = require("path");
+
+/***/ })
+
+/******/ });

dist/index.js

@@ -62,7 +62,7 @@ try {
     const home = process.env['HOME'];
     const homeSsh = home + '/.ssh';
 
-    const privateKey = core.getInput('ssh-private-key').trim();
+    const privateKey = core.getInput('ssh-private-key');
 
     if (!privateKey) {
         core.setFailed("The ssh-private-key argument is empty. Maybe the secret has not been configured, or you are using a wrong secret name in your workflow file.");
@@ -77,8 +77,21 @@ try {
 
     console.log("Starting ssh-agent");
     const authSock = core.getInput('ssh-auth-sock');
-    child_process.execFileSync('ssh-agent', ['-a', authSock]);
+    let sshAgentOutput = ''
-    core.exportVariable('SSH_AUTH_SOCK', authSock);
+    if (authSock && authSock.length > 0) {
+        sshAgentOutput = child_process.execFileSync('ssh-agent', ['-a', authSock]);
+    } else {
+        sshAgentOutput = child_process.execFileSync('ssh-agent')
+    }
+
+    // Extract auth socket path and agent pid and set them as job variables
+    const lines = sshAgentOutput.toString().split("\n")
+    for (const lineNumber in lines) {
+        const matches = /^(SSH_AUTH_SOCK|SSH_AGENT_PID)=(.*); export \1/.exec(lines[lineNumber])
+        if (matches && matches.length > 0) {
+            core.exportVariable(matches[1], matches[2])
+        }
+    }
 
     console.log("Adding private key to agent");
     privateKey.split(/(?=-----BEGIN)/).forEach(function(key) {

index.js

@@ -22,8 +22,21 @@ try {
 
     console.log("Starting ssh-agent");
     const authSock = core.getInput('ssh-auth-sock');
-    child_process.execFileSync('ssh-agent', ['-a', authSock]);
+    let sshAgentOutput = ''
-    core.exportVariable('SSH_AUTH_SOCK', authSock);
+    if (authSock && authSock.length > 0) {
+        sshAgentOutput = child_process.execFileSync('ssh-agent', ['-a', authSock]);
+    } else {
+        sshAgentOutput = child_process.execFileSync('ssh-agent')
+    }
+
+    // Extract auth socket path and agent pid and set them as job variables
+    const lines = sshAgentOutput.toString().split("\n")
+    for (const lineNumber in lines) {
+        const matches = /^(SSH_AUTH_SOCK|SSH_AGENT_PID)=(.*); export \1/.exec(lines[lineNumber])
+        if (matches && matches.length > 0) {
+            core.exportVariable(matches[1], matches[2])
+        }
+    }
 
     console.log("Adding private key to agent");
     privateKey.split(/(?=-----BEGIN)/).forEach(function(key) {

package-lock.json

@@ -5,9 +5,9 @@
     "requires": true,
     "dependencies": {
         "@actions/core": {
-            "version": "1.1.0",
+            "version": "1.2.4",
-            "resolved": "https://registry.npmjs.org/@actions/core/-/core-1.1.0.tgz",
+            "resolved": "https://registry.npmjs.org/@actions/core/-/core-1.2.4.tgz",
-            "integrity": "sha512-KKpo3xzo0Zsikni9tbOsEQkxZBGDsYSJZNkTvmo0gPSXrc98TBOcdTvKwwjitjkjHkreTggWdB1ACiAFVgsuzA==",
+            "integrity": "sha512-YJCEq8BE3CdN8+7HPZ/4DxJjk/OkZV2FFIf+DlZTC/4iBlzYCD5yjRR6eiOS5llO11zbRltIRuKAjMKaWTE6cg==",
             "dev": true
         },
         "@zeit/ncc": {
@@ -15,12 +15,6 @@
             "resolved": "https://registry.npmjs.org/@zeit/ncc/-/ncc-0.20.5.tgz",
             "integrity": "sha512-XU6uzwvv95DqxciQx+aOLhbyBx/13ky+RK1y88Age9Du3BlA4mMPCy13BGjayOrrumOzlq1XV3SD/BWiZENXlw==",
             "dev": true
-        },
-        "child_process": {
-            "version": "1.0.2",
-            "resolved": "https://registry.npmjs.org/child_process/-/child_process-1.0.2.tgz",
-            "integrity": "sha1-sffn/HPSXn/R1FWtyU4UODAYK1o=",
-            "dev": true
         }
     }
 }

package.json

@@ -7,8 +7,10 @@
     "author": "webfactory GmbH <info@webfactory.de>",
     "license": "MIT",
     "devDependencies": {
-        "@actions/core": "^1.1.0",
+        "@actions/core": "^1.2.4",
-        "@zeit/ncc": "^0.20.5",
+        "@zeit/ncc": "^0.20.5"
-        "child_process": "^1.0.2"
+    },
+    "scripts": {
+        "build": "node scripts/build.js"
     }
 }

scripts/build.js

@@ -0,0 +1,35 @@
+const { execSync } = require('child_process')
+const path = require('path')
+const fs = require('fs')
+
+const buildDir = path.join(process.cwd(), 'build')
+const distDir = path.join(process.cwd(), 'dist')
+
+const buildIndexJs = path.join(buildDir, 'index.js')
+const distIndexJs = path.join(distDir, 'index.js')
+const distCleanupJs = path.join(distDir, 'cleanup.js')
+
+if (!fs.existsSync(buildDir)) {
+    fs.mkdirSync(buildDir)
+}
+
+// Build the main index.js file
+console.log('Building index.js...')
+execSync(`./node_modules/.bin/ncc build index.js -q -o ${buildDir}`)
+if (fs.existsSync(distIndexJs)) {
+    fs.unlinkSync(distIndexJs)
+}
+fs.renameSync(buildIndexJs, distIndexJs)
+
+// Build the cleanup.js file
+console.log('Building cleanup.js...')
+execSync(`./node_modules/.bin/ncc build cleanup.js -q -o ${buildDir}`)
+if (fs.existsSync(distCleanupJs)) {
+    fs.unlinkSync(distCleanupJs)
+}
+fs.renameSync(buildIndexJs, distCleanupJs)
+
+console.log('Cleaning up...')
+fs.rmdirSync(buildDir)
+
+console.log('Done')