How do I make cloud-init startup scripts run every time my EC2 instance boots?

Question

I have an EC2 instance running an AMI based on the Amazon Linux AMI. Like all such AMIs, it supports the cloud-init system for running startup scripts based on the User Data

Answer 1

I struggled with this issue for almost two days, tried all of the solutions I could find and finally, combining several approaches, came up with the following:

MyResource:
  Type: AWS::EC2::Instance
  Metadata:
    AWS::CloudFormation::Init:
      configSets:
        setup_process:
          - "prepare"
          - "run_for_instance"
      prepare:
        commands:
          01_apt_update:
            command: "apt-get update"
          02_clone_project:
            command: "mkdir -p /replication && rm -rf /replication/* && git clone https://github.com/awslabs/dynamodb-cross-region-library.git /replication/dynamodb-cross-region-library/"
          03_build_project:
            command: "mvn install -DskipTests=true"
            cwd: "/replication/dynamodb-cross-region-library"
          04_prepare_for_apac:
            command: "mkdir -p /replication/replication-west && rm -rf /replication/replication-west/* && cp /replication/dynamodb-cross-region-library/target/dynamodb-cross-region-replication-1.2.1.jar /replication/replication-west/replication-runner.jar"
      run_for_instance:
        commands:
          01_run:
            command: !Sub "java -jar replication-runner.jar --sourceRegion us-east-1 --sourceTable ${TableName} --destinationRegion ap-southeast-1 --destinationTable ${TableName} --taskName -us-ap >/dev/null 2>&1 &"
            cwd: "/replication/replication-west"
  Properties:
    UserData:
      Fn::Base64:
        !Sub |
          #cloud-config
          cloud_final_modules:
           - [scripts-user, always]
          runcmd:
           - /usr/local/bin/cfn-init -v -c setup_process --stack ${AWS::StackName} --resource MyResource --region ${AWS::Region}
           - /usr/local/bin/cfn-signal -e $? --stack ${AWS::StackName} --resource MyResource --region ${AWS::Region}

This is the setup for DynamoDb cross-region replication process.