Tiny script to brew your dockerfile with ease

dockerfile-brew

#!/usr/bin/env python3
import argparse
import json
import os
from os import path


def get_file_content(path):
    with open(path, "r") as file:
        return file.read()


def set_file_content(path, content):
    with open(path, "w") as file:
        return file.write(content)


def get_config(config_path):
    return json.loads(
       get_file_content(config_path)
    )

# because python std lib sucks a whole bunch!
def resolve_path(target, base):
    if path.isabs(target):
        return target
    return path.join(
       base,
       target
    )


def apply_definition(directory, name, template, definition):
   target_directory = path.join(
      directory,
      path.normpath(name)
   )
   os.makedirs(
      target_directory,
      exist_ok=True
   )
   set_file_content(
      path.join(target_directory, "Dockerfile"),
      template.format(**definition)
   )


def brew(args):
   directory = path.abspath(args["directory"])
   configuration = get_config(
      resolve_path(
         args["configuration"],
         directory
      )
   )
   template = get_file_content(
      resolve_path(
         args["template"],
         directory
      )
   )

   for name, definition in configuration.items():
      apply_definition(directory, name, template, definition)


if __name__ == "__main__":
   p = argparse.ArgumentParser(
      description="Prepare dockerfile's from templates"
   )

   p.add_argument(
      "directory",
      help="Root directory for container dockerfile's to be brewed",
      type=str
   )

   p.add_argument(
      "--template",
      help="Template file path to use for substitution when brewing the container Dockerfile. " +
      "If relative path is given then it will be resolved relatively to root directory(see directory parameter).",
      type=str,
      default="Dockerfile.template"
   )

   p.add_argument(
      "--configuration",
      help="Brew configuration which contains a dictionary " +
      "{name: {...variables...}} for substitution in the template. " +
      "If relative path is given then it will be resolved relatively to root directory, " +
      "just like template argument.",
      type=str,
      default="dockerfile-brew.json"
   )

   brew(p.parse_args().__dict__)