Packer
Build identical machine images for any platform. Packer, from HashiCorp, is a tool for building machine images, such as AWS AMIs, Azure images, Google Cloud images and VM templates, from a single configuration. It starts a temporary machine, runs provisioning steps such as shell scripts or Ansible, and saves the result as an image. This gives you consistent, pre-configured servers that boot quickly.
When it is the right choice
- You run virtual machines and want every server to start from a known, tested image
- You need faster autoscaling because software is baked in, not installed at boot
- You want to rebuild and patch base images on a schedule
- Less useful when your workloads are fully containerised on a managed platform
How we use it
- Write Packer templates that use Ansible for the configuration steps
- Build, test and publish images automatically from CI on every change and on a schedule
- Roll out new images with Terraform and rolling replacement of instances
- Check HashiCorp's current licence terms for Packer as part of tool selection
Ansible
Terraform
AWS
Linux
Packer: frequently asked
Why build images instead of configuring servers at boot?
Baked images start faster and behave the same every time. Boot-time configuration can fail when a package source is down just as you need to scale.
How often should images be rebuilt?
At least whenever security updates are released for the base system. We automate rebuilds so this happens without anyone remembering.
Running Packer, or deciding whether to? Tell us what you have; the first consultation is free.
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