j2cli

Jinja2 command line renderer packaged as a Docker image: exoplatform/j2cli.

It renders *.j2 templates, for instance to generate configuration files in a shell script or a CI job, without installing anything but Docker. The environment variables are the template context.

Since 2.0.0 the image is built on jinjanator (jinjanate), the maintained fork of j2cli. The 1.x tags are the legacy j2cli 0.3.10 (Python 3.10, Jinja2 3.1.2) and are no longer rebuilt.

Current versions: jinjanator 25.3.1, Jinja2 3.1.6, Python 3.14.

Usage

The entrypoint is jinjanate --quiet (no version banner on stderr, only the rendered result on stdout).

cat > hello.j2 <<'TPL'
host={{ DEPLOYMENT_EXT_HOST }}
{% if FEATURE_ENABLED == "true" %}feature is on{% endif %}
{{ MODE | default("SAML", true) }}
TPL

docker run --rm \
  -e DEPLOYMENT_EXT_HOST=acceptance.example.org -e FEATURE_ENABLED=true \
  -v "$PWD":"$PWD":ro \
  exoplatform/j2cli --undefined "$PWD/hello.j2"

• Use --env-file to give all the variables of a file (a multi-lines value isn't supported by Docker in this file).
• --undefined allows undefined variables, which are rendered as empty strings. Without it an undefined variable is an error.
• The template must be mounted in the container (read only is enough). Mounting it on the same absolute path as on the host keeps the paths identical inside and outside the container.
• Don't forward the PATH of your host with --env-file, it would override the one of the container.

Other options of jinjanate (data files in json/yaml/ini/env format, --import-env, ...) are described in the jinjanator documentation.

Without Docker

To use the same renderer directly on your host, without Docker:

pipx install jinjanator
jinjanate --quiet --undefined template.j2

The legacy j2cli doesn't work with the recent Python versions (it imports the removed imp module).

Build

docker build -t exoplatform/j2cli:test .
# use another jinjanator version
docker build --build-arg JINJANATOR_VERSION=25.3.1 -t exoplatform/j2cli:test .

Tests

tests/smoke.sh exoplatform/j2cli:test

The smoke tests check the rendering of environment variables, conditions, filters, undefined variables, blank lines and a clean stderr. They run on each pull request (.github/workflows/ci.yaml) and before each publication.

Publication

The publish GitHub workflow builds the multi-architecture image (linux/amd64, linux/arm64) once the smoke tests are green:

• a push on master publishes the latest tag
• a push of a tag X.Y.Z (for example 2.0.0) publishes this tag

Dependabot proposes the updates of the GitHub actions and of the base image every week. To update jinjanator, change JINJANATOR_VERSION in the Dockerfile.

License

AGPL-3.0