Using AWS CodeBuild to execute Ansible playbooks

I wanted a clean and automate-able way to package third party software into *.deb format (and multiple others, if needed, in the future), and I had three ways to achieve that;

• The simple way: Write a Bash script
• The easy way: Write a Python script
• My chosen method: Write an Ansible role

While all of the options can get me where I wanted, it felt a lot cleaner to go the Ansible route as I can clearly state (and see) what packages I am building either from the command line level or from a playbook level, rather than having to maintain a separate configuration file to drive what to build and where in an alternative format for either the Bash or Python approaches.

The playbook approach also allows me to monitor and execute a build on a remote machine, should I wish to build cross-platform or need larger resources for testing.

In this scenario, I’ll be executing the Ansible role locally on the CodeBuild instance.

Configuring the CodeBuild Environment

Using GitHub as a source

I have one git repository per Ansible playbook, so by linking CodeBuild to the repository in question I’m able to (eventually) automatically trigger the execution of CodeBuild upon a pushed commit on the main branch.

The only additional setting under sources that I define is the Source version, as I don’t want build executions happening for all branches (as that can get costly).

CodeBuild Environment

• Provisioning Model: On-demand
  • I’m not pushing enough packages to require a dedicated fleet, so spinning up VMs in response to a pushed commit (~5 times a week) is good enough.
• Environment Image: Managed Image
  • As stated above, I had my focus towards a proof-of-concept that running Ansible under CodeBuild was possible. A custom image with pre-installed packages is the way to go in the long run.
• Compute: EC2
  • Since I’m targeting *.deb format, I choose Ubuntu as the operating system. The playbook I’m expecting to execute doesn’t require GPU resources either.
  • Amazon Lambda doesn’t support Ubuntu, nor is able to execute Ansible (directly). I’d have to write a wrapper in Python that will execute the Ansible Playbook which is more overhead.
  • Depending on the build time and size of the result package, I had to adjust the memory required accordingly. However, this may be because I’m making use of the /tmp directory by default.

buildspec.yml

I store the following file at the root level of the same Git repository that contains the Ansible playbook.

version: 0.2

phases:
  pre_build:
    commands:
      - apt install -y ansible python3-botocore python3-boto3
      - ansible-galaxy install -r requirements.yaml
      - ansible-galaxy collection install amazon.aws
  build:
    commands:
      - ansible-playbook build.yaml
artifacts:
  files:
    - /tmp/*.deb

I keep the role (and therefore, tasks) separate from the playbook itself, which is why I use ansible-galaxy to install the requirements. Each time the session is started, it pulls down a fresh copy of any requirements. This can differ from playbook to playbook.

I use the role for the execution steps, and the playbook (or inventory) to hold the settings that influence the execution, such as (in this scenario) what the package name is and how to package it.

I explicitly include the amazon.aws Ansible collection in this scenario as I’m using the S3 module to pull down sources (or builds of third party software) and to push build packages up to S3. I’m doing this via Ansible as opposed to storing it within Git due to its’ size, as well as opposed to CodeDeploy as I don’t plan on deploying the packages to infrastructure, rather, to a repository.

I did have some issues using the Artifacts option within CodeBuild also, which lead to pushing from Ansible.

Finally, the ansible-playbook can be executed once all the pre-requisites are needed. The only adaptation that’s needed on the playbook level, is that localhost is listed as a target. This ensures that the playbook will execute on the local machine.

---
- hosts: localhost

Once all the configuration and repository setup is done, the build executed successfully and I received my first Debian package via CodeBuild using Ansible.