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Jinja2 rendering tool

Project description

j2rt is a tool meant to simplify Jinja2 usage for CLI, be that with shell scripts, continuous integration pipelines or anything else, where m4 is not a good fit, with all the whistles and bells that Jinja2 offers, if statements, for loops, filters and many more, see Jinja2’s syntax for list of features. The tool can take template and variable files from local filesystem as well as remote S3. The S3 integration makes it easy to create a secure secrets store for your configuration files, since S3 can be encrypted (KMS or regular server side AES), it’s viable to place secrets.json in S3 and then load it during deployment process for the configuration files to be generated, as one of use cases.

Multiple variable files can be used, in a way that one can, for example, specify one base variables file, and then append some keys, or override others, if needed.

Python dependencies

  • jinja2

  • boto3 (only if s3 is used)

Custom filters

Filters that are supported but are not part of official Jinja2 specification

  • b64decode - decode base64 encoded string into it’s original form.

  • b64encode - encode string into base64.

Installation

From PYPI:

pip install j2rt

From master branch:

pip install https://github.com/slashbeast/j2rt/archive/master.zip

Note: it’s generally unwise to install packages with pip outside of virtualenv, if however this is what you want, append --user to the pip invocation to install it locally for logged user only.

Usage

The template and variable file(s) can be either local, or remote s3, if prefixed with s3://. Template is to be written in jinja2 and variable files are to be JSON formatted. One or more variable files can be specified, the same variable can be set in multiple variable files, the last one to be defined will be used.

usage: j2rt [-h] -t TEMPLATE_FROM
            [-v VARIABLES_FROM [VARIABLES_FROM ...]]
            [-V VARIABLE [VARIABLE ...]] [-o OUTPUT] [--version]

optional arguments:
  -h, --help            show this help message and exit
  -t TEMPLATE_FROM, --template-from TEMPLATE_FROM
                        Path to template file to use
  -v VARIABLES_FROM [VARIABLES_FROM ...], --variables-from VARIABLES_FROM [VARIABLES_FROM ...]
                        The path(s) for JSON files from which
                        variables will be taken from, if variable in
                        file is already defined, it will be
                        overwritten.
  -V VARIABLE [VARIABLE ...], --variable VARIABLE [VARIABLE ...]
                        Set variable from command line, in the format
                        name=value, prefix value with @ to read file
                        into variable, one can escape @ by writting it
                        as @@foo for @foo value. Variables specified
                        at command line have highest priority and will
                        overrride the same variable set in any of
                        --variables-from.
  -o OUTPUT, --output OUTPUT
                        Output file, if not set, result is printed to
                        stdout.
  --version             Show version and exit

Examples

Generate nginx.conf

j2rt \
  -t s3://somebucket/nginx.conf.j2 \
  -v /etc/nginx.conf.base.json -v s3://somebucket/nginx.conf.webserver.json \
  >/etc/nginx.conf

(Re)generate configuration for all the nginx’s vhosts

true >/etc/nginx/conf.d/vhosts.conf && \
for vhost in vhosts/*.json; do
  j2rt -t nginx.vhost.conf.j2 -v "$vhost" >>/etc/nginx/conf.d/vhosts.conf
done && nginx -s reload

Generate .env with production configuration and secrets, taking secrets from (encrypted) S3 bucket.

j2rt \
  -t .env.j2 \
  -v .env.base.json -v .env.prod.json -v s3://somebucket/.env.prod.secrets.json \
  -o .env

Generate OpenVPN client config file, taking CA.crt from S3 bucket, while client certificate and other keys taken from local file system:

j2rt \
  --template-from /etc/openvpn/client.ovpn.j2 \
  --variables-from /etc/openvpn/base_configuration_subnets_routing_tables_etc.json \
  --variable server_name=TEST_SERVER \
  --variable CA_CRT=@s3://somebucket/ca.crt \
  --variable client_crt=@/path/to/pki/certs/client1.crt \
  --variable client_key=@/path/to/pki/keys/client1.key \
  --variable ta_key=@/etc/openvpn/ta.key \
  -o /root/client1.ovpn

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