Build Automation with Packer

Packer is a tool for creating images from a single source configuration. Using this Packer template reduces the entire process of creating, configuring, validating, and snapshotting a build Droplet to a single command:

packer build marketplace-image.pkr.hcl

This Packer template uses the same LAMP-based example as the Fabric sample project. Like the Fabric sample project, you can modify this template to use as a starting point for your image.

Usage

To run the LAMP example that this template uses by default, you'll need to install Packer and create a DigitalOcean personal access token and set it to the DIGITALOCEAN_TOKEN environment variable. Running packer build marketplace-image.pkr.hcl without any other modifications will create a build Droplet configured with LAMP, clean and verify it, then power it down and snapshot it.

⚠️ The image validation script in scripts/99-img_check.sh is copied from the top-level scripts directory in this repository. The top-level location is the script's canonical source, so make sure you're using the latest version from there.

To start adapting this template for your own image, there are some variables that can be set:

• image_name defines the name of the resulting snapshot, which by default is mastodon-digitalocean- with a UNIX timestamp appended.

You can also modify these variables at runtime by using the -var flag.

Configuration Details

By using Packer's DigitalOcean Builder to integrate with the DigitalOcean API, this template fully automates Marketplace image creation.

This template uses Packer's file provisioner to upload complete directories to the Droplet. The contents of files/var/ will be uploaded to /var/. Likewise, the contents of files/etc/ will be uploaded to /etc/. One important thing to note about the file provisioner, from Packer's docs:

The destination directory must already exist. If you need to create it, use a shell provisioner just prior to the file provisioner in order to create the directory. If the destination directory does not exist, the file provisioner may succeed, but it will have undefined results.

This template also uses Packer's shell provisioner to run scripts from the /scripts directory and install APT packages using an inline task.

Learn more about using Packer in the official Packer documentation.