configtpl 1.0.1

Configuration builder which combines features of Jinja and YAML

configtpl

This library builds configuration in two stages:

1. Renders the provided configuration as Jinja templates
2. Parses the rendered data as YAML file

Features

• Uses Jinja2 and Yaml capabilities to build a dynamic configuration
• Multiple configuration files might be passed. The library merges all of them into single config.
• Basic confuration includes Jinja functions and filters for general-purpose tasks:
  • Reading the environment variables
  • Execution of system commands
  • Hashing

Standard features

Filters

In addition to Jinja buildin filters, the library provides the following ones:

Filter	Description
base64	Base64 encoding
base64_decode	Base64 decoding
md5	MD5 hash
sha256	SHA-256 hash
sha512	SHA-512 hash
split_space	Splits a string with space separator into list of strings

Functions

See also List of Global Functions on Jinja page

            "cmd": jinja_globals.jinja_global_cmd,
            "cwd": jinja_globals.jinja_global_cwd,
            "env": jinja_globals.jinja_global_env,
            "file": jinja_globals.jinja_global_file,
            "uuid": jinja_globals.jinja_global_uuid,

Function	Description
cmd(cmd: str)	Executes a system command and returns the standard output
cwd()	Returns the current working directory
env(name: str, default: str)	Returns the value of enviroment variable name if it exists,
	or falls back to default value otherwise
file(path: str)	Reads the file and returns the contents
uuid	Generates a UUID e.g 1f6c868d-f9b7-4d3f-b7c9-48048b065019

Examples

You can check the functional tests folder for more examples.

A very simple example of usage is provided below:

# my_first_config.cfg

{% set my_val = "abc" %}
app:
  param_env: "{{ env('MY_ENV_VAR', 'default') }}"
  param1: "{{ my_val }}"

# my_second_config.cfg

app:
  param2: def
  param3: "{{ app.param1 }}123"
hash: "{{ app.param1 | md5 }}"

# app.py

import json
from configtpl.config_builder import ConfigBuilder

builder = ConfigBuilder()
cfg = builder.build_from_files("my_first_config.cfg:my_second_config.cfg")
print(json.dumps(cfg, indent=2))

# Execution

MY_ENV_VAR=testing python ./app.py

# output
{
  "app": {
    "param_env": "testing",
    "param1": "abc",
    "param2": "def",
    "param3": "abc123"
  },
  "hash": "900150983cd24fb0d6963f7d28e17f72"
}