EC2 launch template support

README.md

@@ -194,6 +194,7 @@ Now you're ready to go!
 | `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> |
+| `ec2-launch-template`                                                                                                                                                              | Optional. Used only with the `start` mode. | Specifies an existing EC2 launch template (by name), which can be used to define image ID, instance type, subnet ID, security group IDs, spot options etc<br><br> |
 
 ### Environment variables
 

action.yml

@@ -65,6 +65,10 @@ inputs:
     description: >-
       Directory that contains actions-runner software and scripts. E.g. /home/runner/actions-runner.
     required: false
+  ec2-launch-template:
+    description: >-
+      EC2 launch template name. A launch template may be used to specify AMI, instance type etc parameters
+    required: false
 outputs:
   label:
     description: >-

src/aws.js

@@ -47,6 +47,12 @@ async function startEc2Instance(label, githubRegistrationToken) {
     TagSpecifications: config.tagSpecifications,
   };
 
+  if (config.input.ec2LaunchTemplate) {
+    params.LaunchTemplate = {
+      LaunchTemplateName: config.input.ec2LaunchTemplate
+    };
+  }
+
   try {
     const result = await ec2.runInstances(params).promise();
     const ec2InstanceId = result.Instances[0].InstanceId;

src/config.js

@@ -14,6 +14,7 @@ class Config {
       ec2InstanceId: core.getInput('ec2-instance-id'),
       iamRoleName: core.getInput('iam-role-name'),
       runnerHomeDir: core.getInput('runner-home-dir'),
+      ec2LaunchTemplate: core.getInput('ec2-launch-template'),
     };
 
     const tags = JSON.parse(core.getInput('aws-resource-tags'));
@@ -43,7 +44,9 @@ class Config {
     }
 
     if (this.input.mode === 'start') {
-      if (!this.input.ec2ImageId || !this.input.ec2InstanceType || !this.input.subnetId || !this.input.securityGroupId) {
+      const isSet = param => param;
+      const params = [this.input.ec2ImageId, this.input.ec2InstanceType, this.input.subnetId, this.input.securityGroupId];
+      if (!(this.input.ec2LaunchTemplate || params.every(isSet))) {
         throw new Error(`Not all the required inputs are provided for the 'start' mode`);
       }
     } else if (this.input.mode === 'stop') {