Packer "Failed to initialize" from packer init in CI

By Daniel Zoghalchali·Latchkey

Packer 1.7 and later moved builders and provisioners into separately installed plugins. When a template lists required_plugins, packer build fails until packer init has downloaded them into the runner.

What this error means

packer build stops with "Error: Failed to initialize" or a message pointing you to run packer init, because the template references a plugin the runner does not have.

Error: Failed to initialize

Error: 1 error occurred:
	* Failed to initialize build: required plugin "github.com/hashicorp/amazon" is not installed. Run "packer init".

Common causes

packer init never ran on the ephemeral runner

The template declares required_plugins, but the CI job jumped straight to packer build. A fresh runner has no plugins cached, so initialization fails.

The plugin cache is not persisted between jobs

Even if a prior job ran init, a new ephemeral runner starts empty. Without a step that runs init or restores a cache, plugins are missing again.

How to fix it

Run packer init before build

1. Add a packer init step against the template directory.
2. Run it before packer validate and packer build.
3. Confirm the plugin resolves against your required_plugins block.

- run: packer init .
- run: packer validate .
- run: packer build .

Cache the plugin directory across runs

Persist the Packer plugin path so repeat jobs skip re-downloading and init is fast.

- uses: actions/cache@v4
  with:
    path: ~/.config/packer/plugins
    key: packer-plugins-${{ hashFiles('**/*.pkr.hcl') }}

How to prevent it

• Always run packer init before build in CI, not only locally.
• Cache the plugin directory keyed on your template files.
• Keep required_plugins version constraints pinned so init is reproducible.

Frequently asked questions

Related guides

References

• Terraform documentation
• GitHub Actions documentation