I've been looking at various methods to run commands upon creation of EC2 instances using Elastic Beanstalk on AWS. I've been given different methods to do this through AWS Tech Support, including life cycle hooks, custom AMI's, and .ebextensions. I've been having issues getting the first 2 methods (life cycle hooks and custom AMIs) to work with EB.
I'm currently using .ebextensions to run commands upon deploy, but not sure if there's a way to run a set of commands upon creation only instead of every time I deploy code. For instance, I have a file .ebextensions/03-commands.config that contains the following code:
container_commands:
01_npm_install:
command: "npm install -g -f npm@latest"
However, I only want this code to run upon instance creation, not every time I deploy, as it currently does. Does anyone know a way to accomplish this?
Thanks in advance!
I would recommend creating an idempotent script in your application that leaves a marker file on the instance in some location say /var/myapp/marker using something like mkdir -p /var/myapp-state/; touch /var/myapp-state/marker on successful execution. That way in your script you can check that if the marker file exists you can make your script a no-op.
Then you can call your script from container commands but it will be a no-op everytime because on first successful execution it will create the marker file and subsequent executions will be no-ops.
Create a custom AMI. This way you can setup your instances whoever you want and they will launch faster
http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/using-features.customenv.html
Update
I don't understand why someone would down vote this. Anyway, as it also has been said in comments, custom AMI's are a great way to create custom behaviour on your instances.
As I see from you question, you're using: container_commands, that is means you are using Elastic Beanstalk with Docker. Right? In this case I would recommended to read: http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/create_deploy_docker.html.
The idea is following, that you can create own Dockerfile, where you can specify all commands that you need to build a docker container, for example to install all dependencies.
I would recommended to use .ebextensions for the Elastic Beanstalk customization and configuration, for example to specify ELB or RDS configuration. In the Dockerfile make sense to specify all commands, that you need to build a container for your application, that includes setup of the web server, dependencies etc.
With this approach, Elastic Beanstalk will build a container, that each time when you do deploy, it execute a docker instance with deployed source code.