feat: Add variable to specify custom commands while building the AMI (#1838)

Add ability to specify custom commands while building the AMI
This can be used to install additional software or to customize anything else for the final AMI

Author: ulich

Diff for: images/linux-amzn2/github_agent.linux.pkr.hcl

@@ -72,6 +72,12 @@ variable "snapshot_tags" {
   default     = {}
 }
 
+variable "custom_shell_commands" {
+  description = "Additional commands to run on the EC2 instance, to customize the instance, like installing packages"
+  type        = list(string)
+  default     = []
+}
+
 source "amazon-ebs" "githubrunner" {
   ami_name                    = "github-runner-amzn2-x86_64-${formatdate("YYYYMMDDhhmm", timestamp())}"
   instance_type               = var.instance_type
@@ -118,15 +124,15 @@ build {
   ]
   provisioner "shell" {
     environment_vars = []
-    inline = [
+    inline = concat([
       "sudo yum update -y",
       "sudo yum install -y amazon-cloudwatch-agent curl jq git",
       "sudo amazon-linux-extras install docker",
       "sudo systemctl enable docker.service",
       "sudo systemctl enable containerd.service",
       "sudo service docker start",
       "sudo usermod -a -G docker ec2-user",
-    ]
+    ], var.custom_shell_commands)
   }
 
   provisioner "file" {

Diff for: images/ubuntu-focal/github_agent.ubuntu.pkr.hcl

@@ -72,6 +72,12 @@ variable "snapshot_tags" {
   default     = {}
 }
 
+variable "custom_shell_commands" {
+  description = "Additional commands to run on the EC2 instance, to customize the instance, like installing packages"
+  type        = list(string)
+  default     = []
+}
+
 source "amazon-ebs" "githubrunner" {
   ami_name                    = "github-runner-ubuntu-focal-amd64-${formatdate("YYYYMMDDhhmm", timestamp())}"
   instance_type               = var.instance_type
@@ -120,7 +126,7 @@ build {
     environment_vars = [
       "DEBIAN_FRONTEND=noninteractive"
     ]
-    inline = [
+    inline = concat([
       "sudo apt-get -y update",
       "sudo apt-get -y install ca-certificates curl gnupg lsb-release",
       "sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg",
@@ -136,7 +142,7 @@ build {
       "sudo curl -f https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip -o awscliv2.zip",
       "unzip awscliv2.zip",
       "sudo ./aws/install",
-    ]
+    ], var.custom_shell_commands)
   }
 
   provisioner "file" {

Diff for: images/windows-core-2019/github_agent.windows.pkr.hcl

@@ -31,6 +31,12 @@ variable "associate_public_ip_address" {
   default     = null
 }
 
+variable "custom_shell_commands" {
+  description = "Additional commands to run on the EC2 instance, to customize the instance, like installing packages"
+  type        = list(string)
+  default     = []
+}
+
 source "amazon-ebs" "githubrunner" {
   ami_name                    = "github-runner-windows-core-2019-${formatdate("YYYYMMDDhhmm", timestamp())}"
   communicator                = "winrm"
@@ -78,8 +84,10 @@ build {
   }
 
   provisioner "powershell" {
-    inline = [templatefile("./windows-provisioner.ps1", {
-      action_runner_url = var.action_runner_url
-    })]
+    inline = concat([
+      templatefile("./windows-provisioner.ps1", {
+        action_runner_url = var.action_runner_url
+      })
+    ], var.custom_shell_commands)
   }
 }