Allow user to pass in a custom actions-runner directory (#56)

* Allow user to pass in a custom actions-runner directory which contains pre-installed runner software and scripts

* Add comment

* Fix input refs

* Fix linter error

Author: jpalomaki

README.md

@@ -193,6 +193,7 @@ Now you're ready to go!
 | `ec2-instance-id`                                                                                                                                                            | Required if you use the `stop` mode.       | EC2 Instance Id of the created runner. <br><br> The id is provided by the output of the action in the `start` mode. <br><br> The id is used to terminate the EC2 instance when the runner is not needed anymore.                                                                                                                      |
 | `iam-role-name`                                                                                                                                                              | Optional. Used only with the `start` mode. | IAM role name to attach to the created EC2 runner. <br><br> This allows the runner to have permissions to run additional actions within the AWS account, without having to manage additional GitHub secrets and AWS users. <br><br> Setting this requires additional AWS permissions for the role launching the instance (see above). |
 | `aws-resource-tags`                                                                                                                                                          | Optional. Used only with the `start` mode. | Specifies tags to add to the EC2 instance and any attached storage. <br><br> This field is a stringified JSON array of tag objects, each containing a `Key` and `Value` field (see example below). <br><br> Setting this requires additional AWS permissions for the role launching the instance (see above).                         |
+| `runner-home-dir`                                                                                                                                                              | Optional. Used only with the `start` mode. | Specifies a directory where pre-installed actions-runner software and scripts are located.<br><br> |
 
 ### Environment variables
 

action.yml

@@ -61,6 +61,10 @@ inputs:
       for example: '[{"Key": "TagKey1", "Value": "TagValue1"}, {"Key": "TagKey2", "Value": "TagValue2"}]'
     required: false
     default: '[]'
+  runner-home-dir:
+    description: >-
+      Directory that contains actions-runner software and scripts. E.g. /home/runner/actions-runner.
+    required: false
 outputs:
   label:
     description: >-

src/aws.js

@@ -2,22 +2,38 @@ const AWS = require('aws-sdk');
 const core = require('@actions/core');
 const config = require('./config');
 
+// User data scripts are run as the root user
+function buildUserDataScript(githubRegistrationToken, label) {
+  if (config.input.runnerHomeDir) {
+    // If runner home directory is specified, we expect the actions-runner software (and dependencies)
+    // to be pre-installed in the AMI, so we simply cd into that directory and then start the runner
+    return [
+      '#!/bin/bash',
+      `cd "${config.input.runnerHomeDir}"`,
+      'export RUNNER_ALLOW_RUNASROOT=1',
+      'export DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=1',
+      `./config.sh --url https://github.com/${config.githubContext.owner}/${config.githubContext.repo} --token ${githubRegistrationToken} --labels ${label}`,
+      './run.sh',
+    ];
+  } else {
+    return [
+      '#!/bin/bash',
+      'mkdir actions-runner && cd actions-runner',
+      'case $(uname -m) in aarch64) ARCH="arm64" ;; amd64|x86_64) ARCH="x64" ;; esac && export RUNNER_ARCH=${ARCH}',
+      'curl -O -L https://github.com/actions/runner/releases/download/v2.278.0/actions-runner-linux-${RUNNER_ARCH}-2.278.0.tar.gz',
+      'tar xzf ./actions-runner-linux-${RUNNER_ARCH}-2.278.0.tar.gz',
+      'export RUNNER_ALLOW_RUNASROOT=1',
+      'export DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=1',
+      `./config.sh --url https://github.com/${config.githubContext.owner}/${config.githubContext.repo} --token ${githubRegistrationToken} --labels ${label}`,
+      './run.sh',
+    ];
+  }
+}
+
 async function startEc2Instance(label, githubRegistrationToken) {
   const ec2 = new AWS.EC2();
 
-  // User data scripts are run as the root user.
-  // Docker and git are necessary for GitHub runner and should be pre-installed on the AMI.
-  const userData = [
-    '#!/bin/bash',
-    'mkdir actions-runner && cd actions-runner',
-    'case $(uname -m) in aarch64) ARCH="arm64" ;; amd64|x86_64) ARCH="x64" ;; esac && export RUNNER_ARCH=${ARCH}',
-    'curl -O -L https://github.com/actions/runner/releases/download/v2.278.0/actions-runner-linux-${RUNNER_ARCH}-2.278.0.tar.gz',
-    'tar xzf ./actions-runner-linux-${RUNNER_ARCH}-2.278.0.tar.gz',
-    'export RUNNER_ALLOW_RUNASROOT=1',
-    'export DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=1',
-    `./config.sh --url https://github.com/${config.githubContext.owner}/${config.githubContext.repo} --token ${githubRegistrationToken} --labels ${label}`,
-    './run.sh',
-  ];
+  const userData = buildUserDataScript(githubRegistrationToken, label);
 
   const params = {
     ImageId: config.input.ec2ImageId,

src/config.js

@@ -13,6 +13,7 @@ class Config {
       label: core.getInput('label'),
       ec2InstanceId: core.getInput('ec2-instance-id'),
       iamRoleName: core.getInput('iam-role-name'),
+      runnerHomeDir: core.getInput('runner-home-dir'),
     };
 
     const tags = JSON.parse(core.getInput('aws-resource-tags'));