Packer version and Bring Your Own Packer

image-builder uses HashiCorp Packer to drive every image build. The repository pins Packer to version 1.9.5, which is the last release under the MPL-2.0 license. Beginning with v1.10.0, HashiCorp relicensed Packer under the Business Source License (BUSL).

images/capi/hack/ensure-packer.sh installs the pinned version into images/capi/.local/bin whenever make deps-* runs.

Why the pin?

Kubernetes-sigs projects depend only on open-source-licensed tooling. The pin to the last MPL-2.0 Packer release lets image-builder continue to be used and distributed without inheriting the BUSL terms.

Bring Your Own Packer

You can override the pinned Packer in three ways. These knobs are recognized by both hack/ensure-packer.sh and the Makefile, and apply to every make build-* / make validate-* target.

Variable	Default	Effect
`PACKER_BIN`	unset	Absolute path to an existing Packer binary. `ensure-packer.sh` validates it and exits; the `Makefile` uses it for every `packer init`/`build`/`validate`. Highest precedence.
`PACKER_VERSION`	`1.9.5`	Version that `ensure-packer.sh` downloads into `.local/bin` when it manages Packer itself.
`IB_ALLOW_ANY_PACKER`	`0`	Set to `1` to accept whatever `packer` is already on `PATH` instead of having `ensure-packer.sh` replace it with the pinned version. Emits a license warning if the detected Packer is >= 1.10.0 (BUSL).

You can also override the binary directly on the make command line:

make PACKER=/opt/packer/packer build-ami-ubuntu-2404

Examples

Use a Packer you already have installed:

export PACKER_BIN=/usr/local/bin/packer
make deps-azure
make build-azure-sig-ubuntu-2404

Use a newer Packer version, downloaded into .local/bin:

export PACKER_VERSION=1.11.2
make deps-ami
make build-ami-ubuntu-2404

Accept the Packer that’s already on your PATH without downgrading it:

export IB_ALLOW_ANY_PACKER=1
make deps-common

Container image

The same knobs are exposed as Dockerfile build args:

docker build \
  --build-arg PACKER_VERSION=1.11.2 \
  --build-arg IB_ALLOW_ANY_PACKER=1 \
  -t my/image-builder:byo-packer \
  images/capi

PACKER_BIN is intentionally only a runtime knob — pass it via docker run --env PACKER_BIN=/path/in/container/to/packer ... if you mount a binary into the container.

Compatibility notes — please read

License: Using Packer >= 1.10.0 means you accept the BUSL terms. image-builder makes no representation about your obligations under that license.
Plugins: Each provider’s packer/<provider>/config.pkr.hcl declares a pinned required_plugins block. packer init resolves those regardless of which Packer version you use. Newer Packer releases are generally backward compatible with the plugin versions we pin, but specific combinations are not tested by the project’s CI.
Support: Bug reports against builds run with anything other than the default Packer (1.9.5) are best-effort. If you hit a problem, please first try reproducing with the default before opening an issue.
packer init cache: If you switch Packer versions mid-checkout you may need to clear ~/.packer.d/plugins or run packer init -upgrade inside images/capi to refresh the local plugin cache.

The Image Builder Book