J2 - the minimalist Jinja2 CLI

Inspiration

I wanted a simple CLI for Jinja2 that operated similarly to Helm:

• Render a template from a file
• Pass custom values from a yaml file
• Override custom values directly on the command line
• Allow custom filters to be provided from a file

This CLI aims to provide these features in the simplest way possible.

Usage

❯ j2 --help
a minimalist Jinja2 CLI

usage: j2 [-h] [--values [value.yaml]] [--set my.value=42]
          template

positional arguments:
  template              Template file to process

optional arguments:
  -h, --help            show this help message and exit
  --values [value.yaml]
                        Input values file path; "-" to use stdin
  --filters [filters.py]
                        Custom Jinja2 filters from Python file. Loads all
                        top-level functions and registers them as filters.
  --set my.value=42     Set values on the command line. Can be used multiple
                        times.

Docker

The j2 CLI is available as a Docker image hosted on Docker Hub: https://hub.docker.com/r/thecodesmith/j2.

Run j2 locally in Docker with an alias like this:

alias j2='docker run -it --rm -w /app -v $PWD:/app thecodesmith/j2 j2'

Examples

Basic usage:

j2 manifest.j2 --values values.yaml > manifest.yaml

With custom values overridden on the command line:

j2 manifest.j2 --values values.yaml --set app.namespace=foo > manifest.yaml

With custom filters defined in a file:

j2 manifest.j2 --filters filters.py > manifest.yaml

Where the filters file looks like this:

def parentheses(value):
    """ Usage: {{ var | parentheses }} """
    return '(' + value + ')'