Support multiple EC2 runners

The code here is based upon machulav#82
with some updates to match the latest runner version. My IDE also decided to
run a formatter, so there are a few formatting changes that don't change
functionality.

Author: brianjaustin

action.yml

@@ -20,6 +20,11 @@ inputs:
       EC2 Image Id (AMI). The new runner will be launched from this image.
       This input is required if you use the 'start' mode.
     required: false
+  ec2-instance-count:
+    description: >-
+      Number of EC2 runners to launch, defaults to 1.
+    required: false
+    default: '1'
   ec2-instance-type:
     description: >-
       EC2 Instance Type. 
@@ -43,12 +48,13 @@ inputs:
       The label is used to remove the runner from GitHub when the runner is not needed anymore.
       This input is required if you use the 'stop' mode.
     required: false
-  ec2-instance-id:
+  ec2-instance-ids:
     description: >-
-      EC2 Instance Id of the created runner.
+      EC2 Instance Id(s) of the created runner(s).
       The id is used to terminate the EC2 instance when the runner is not needed anymore.
       This input is required if you use the 'stop' mode.
     required: false
+    default: 'null'
   iam-role-name:
     description: >-
       IAM Role Name to attach to the created EC2 instance.
@@ -77,9 +83,9 @@ outputs:
       The label is used in two cases:
       - to use as the input of 'runs-on' property for the following jobs;
       - to remove the runner from GitHub when it is not needed anymore.
-  ec2-instance-id:
+  ec2-instance-ids:
     description: >-
-      EC2 Instance Id of the created runner.
+      EC2 Instance Id(s) of the created runner(s).
       The id is used to terminate the EC2 instance when the runner is not needed anymore.
 runs:
   using: node20

src/aws.js

@@ -40,8 +40,8 @@ async function startEc2Instance(label, githubRegistrationToken) {
   const params = {
     ImageId: config.input.ec2ImageId,
     InstanceType: config.input.ec2InstanceType,
-    MinCount: 1,
-    MaxCount: 1,
+    MinCount: config.input.ec2InstanceCount,
+    MaxCount: config.input.ec2InstanceCount,
     UserData: Buffer.from(userData.join('\n')).toString('base64'),
     SubnetId: config.input.subnetId,
     SecurityGroupIds: [config.input.securityGroupId],
@@ -51,9 +51,9 @@ async function startEc2Instance(label, githubRegistrationToken) {
 
   try {
     const result = await ec2.runInstances(params).promise();
-    const ec2InstanceId = result.Instances[0].InstanceId;
-    core.info(`AWS EC2 instance ${ec2InstanceId} is started`);
-    return ec2InstanceId;
+    const ec2InstanceIds = result.Instances.map((inst) => inst.InstanceId);
+    core.info(`AWS EC2 instances ${ec2InstanceIds} are started`);
+    return ec2InstanceIds;
   } catch (error) {
     core.error('AWS EC2 instance starting error');
     throw error;
@@ -64,32 +64,32 @@ async function terminateEc2Instance() {
   const ec2 = new AWS.EC2();
 
   const params = {
-    InstanceIds: [config.input.ec2InstanceId],
+    InstanceIds: config.input.ec2InstanceIds,
   };
 
   try {
     await ec2.terminateInstances(params).promise();
-    core.info(`AWS EC2 instance ${config.input.ec2InstanceId} is terminated`);
+    core.info(`AWS EC2 instance ${config.input.ec2InstanceIds} are terminated`);
     return;
   } catch (error) {
-    core.error(`AWS EC2 instance ${config.input.ec2InstanceId} termination error`);
+    core.error(`AWS EC2 instance ${config.input.ec2InstanceIds} termination error`);
     throw error;
   }
 }
 
-async function waitForInstanceRunning(ec2InstanceId) {
+async function waitForInstanceRunning(ec2InstanceIds) {
   const ec2 = new AWS.EC2();
 
   const params = {
-    InstanceIds: [ec2InstanceId],
+    InstanceIds: ec2InstanceIds,
   };
 
   try {
     await ec2.waitFor('instanceRunning', params).promise();
-    core.info(`AWS EC2 instance ${ec2InstanceId} is up and running`);
+    core.info(`AWS EC2 instances ${ec2InstanceIds} are up and running`);
     return;
   } catch (error) {
-    core.error(`AWS EC2 instance ${ec2InstanceId} initialization error`);
+    core.error(`AWS EC2 instances ${ec2InstanceIds} initialization error`);
     throw error;
   }
 }

src/config.js

@@ -11,7 +11,8 @@ class Config {
       subnetId: core.getInput('subnet-id'),
       securityGroupId: core.getInput('security-group-id'),
       label: core.getInput('label'),
-      ec2InstanceId: core.getInput('ec2-instance-id'),
+      ec2InstanceCount: core.getInput('ec2-instance-count'),
+      ec2InstanceIds: JSON.parse(core.getInput('ec2-instance-ids')),
       iamRoleName: core.getInput('iam-role-name'),
       runnerHomeDir: core.getInput('runner-home-dir'),
       preRunnerScript: core.getInput('pre-runner-script'),
@@ -20,7 +21,10 @@ class Config {
     const tags = JSON.parse(core.getInput('aws-resource-tags'));
     this.tagSpecifications = null;
     if (tags.length > 0) {
-      this.tagSpecifications = [{ResourceType: 'instance', Tags: tags}, {ResourceType: 'volume', Tags: tags}];
+      this.tagSpecifications = [
+        { ResourceType: 'instance', Tags: tags },
+        { ResourceType: 'volume', Tags: tags },
+      ];
     }
 
     // the values of github.context.repo.owner and github.context.repo.repo are taken from
@@ -48,7 +52,7 @@ class Config {
         throw new Error(`Not all the required inputs are provided for the 'start' mode`);
       }
     } else if (this.input.mode === 'stop') {
-      if (!this.input.label || !this.input.ec2InstanceId) {
+      if (!this.input.label || !this.input.ec2InstanceIds) {
         throw new Error(`Not all the required inputs are provided for the 'stop' mode`);
       }
     } else {

src/gh.js

@@ -5,13 +5,13 @@ const config = require('./config');
 
 // use the unique label to find the runner
 // as we don't have the runner's id, it's not possible to get it in any other way
-async function getRunner(label) {
+async function getRunners(label) {
   const octokit = github.getOctokit(config.input.githubToken);
 
   try {
     const runners = await octokit.paginate('GET /repos/{owner}/{repo}/actions/runners', config.githubContext);
     const foundRunners = _.filter(runners, { labels: [{ name: label }] });
-    return foundRunners.length > 0 ? foundRunners[0] : null;
+    return foundRunners.length > 0 ? foundRunners : null;
   } catch (error) {
     return null;
   }
@@ -32,22 +32,27 @@ async function getRegistrationToken() {
 }
 
 async function removeRunner() {
-  const runner = await getRunner(config.input.label);
+  const runners = await getRunners(config.input.label);
   const octokit = github.getOctokit(config.input.githubToken);
 
   // skip the runner removal process if the runner is not found
-  if (!runner) {
-    core.info(`GitHub self-hosted runner with label ${config.input.label} is not found, so the removal is skipped`);
+  if (!runners) {
+    core.info(`GitHub self-hosted runners with label ${config.input.label} not found, so the removal is skipped`);
     return;
   }
 
-  try {
-    await octokit.request('DELETE /repos/{owner}/{repo}/actions/runners/{runner_id}', _.merge(config.githubContext, { runner_id: runner.id }));
-    core.info(`GitHub self-hosted runner ${runner.name} is removed`);
-    return;
-  } catch (error) {
-    core.error('GitHub self-hosted runner removal error');
-    throw error;
+  const errors = runners.reduce(async (errors, runner) => {
+    try {
+      await octokit.request('DELETE /repos/{owner}/{repo}/actions/runners/{runner_id}', _.merge(config.githubContext, { runner_id: runner.id }));
+      core.info(`GitHub self-hosted runner ${runner.name} is removed`);
+    } catch (error) {
+      core.error(`GitHub self-hosted runner ${runner} removal error: ${error}`);
+      errors.push(error);
+    }
+    return errors;
+  });
+  if (errors.length > 0) {
+    core.setFailure('Encountered error(s) removing self-hosted runner(s)');
   }
 }
 
@@ -58,21 +63,23 @@ async function waitForRunnerRegistered(label) {
   let waitSeconds = 0;
 
   core.info(`Waiting ${quietPeriodSeconds}s for the AWS EC2 instance to be registered in GitHub as a new self-hosted runner`);
-  await new Promise(r => setTimeout(r, quietPeriodSeconds * 1000));
+  await new Promise((r) => setTimeout(r, quietPeriodSeconds * 1000));
   core.info(`Checking every ${retryIntervalSeconds}s if the GitHub self-hosted runner is registered`);
 
   return new Promise((resolve, reject) => {
     const interval = setInterval(async () => {
-      const runner = await getRunner(label);
+      const runners = await getRunners(label);
 
       if (waitSeconds > timeoutMinutes * 60) {
         core.error('GitHub self-hosted runner registration error');
         clearInterval(interval);
-        reject(`A timeout of ${timeoutMinutes} minutes is exceeded. Your AWS EC2 instance was not able to register itself in GitHub as a new self-hosted runner.`);
+        reject(
+          `A timeout of ${timeoutMinutes} minutes is exceeded. Your AWS EC2 instance was not able to register itself in GitHub as a new self-hosted runner.`
+        );
       }
 
-      if (runner && runner.status === 'online') {
-        core.info(`GitHub self-hosted runner ${runner.name} is registered and ready to use`);
+      if (runners && runners.every((runner) => runner.status === 'online')) {
+        core.info(`GitHub self-hosted runners ${runners} are registered and ready to use`);
         clearInterval(interval);
         resolve();
       } else {

src/index.js

@@ -3,17 +3,17 @@ const gh = require('./gh');
 const config = require('./config');
 const core = require('@actions/core');
 
-function setOutput(label, ec2InstanceId) {
+function setOutput(label, ec2InstanceIds) {
   core.setOutput('label', label);
-  core.setOutput('ec2-instance-id', ec2InstanceId);
+  core.setOutput('ec2-instance-ids', ec2InstanceIds);
 }
 
 async function start() {
   const label = config.generateUniqueLabel();
   const githubRegistrationToken = await gh.getRegistrationToken();
-  const ec2InstanceId = await aws.startEc2Instance(label, githubRegistrationToken);
-  setOutput(label, ec2InstanceId);
-  await aws.waitForInstanceRunning(ec2InstanceId);
+  const ec2InstanceIds = await aws.startEc2Instance(label, githubRegistrationToken);
+  setOutput(label, ec2InstanceIds);
+  await aws.waitForInstanceRunning(ec2InstanceIds);
   await gh.waitForRunnerRegistered(label);
 }