#!/usr/bin/python3

"""

gen-user-data

This tool generates a cloud-config user-data file from a directory containing

configuration. Its main purpose is to make it easy to include files in the

user-data, which need to be encoded in base64.

It writes the assembled user-data to standard out.

The configuration directory may contain:

* user-data.yml -- a base user-data. Anything that exists in this file will be

                   transferred as-is. Any additional configuration is appended

                   to already existing configuration.

* files/        -- a directory containing additional files to include. The

                   file's path on the target system mirrors its path relative

                   to this directore (`files/etc/hosts` → `/etc/hosts`). Its

                   permissions are copied over, but the owner will always be

                   root:root. Empty directories are ignored.

"""

import argparse

import base64

import json

import os

import stat

import sys

def octal_mode_string(mode):

    """Convert stat.st_mode to the format cloud-init expects.

    cloud-init's write_files plugin expects file permissions in the format

    returned by python2's oct() function, for example '0644'. In python3, oct()

    returns a string in the new octal notation, '0o644'.

    """

    return "0" + oct(stat.S_IMODE(mode))[2:]

def main():

    p = argparse.ArgumentParser(description="Generate cloud-config user-data")

    p.add_argument("configdir", metavar="CONFIGDIR", help="input directory")

    args = p.parse_args()

    write_files = []

    filesdir = f"{args.configdir}/files"

    for directory, dirs, files in os.walk(filesdir, followlinks=True):

        for name in files:

            path = f"{directory}/{name}"

            with open(path, "rb") as f:

                content = base64.b64encode(f.read()).decode("utf-8")

            write_files.append({

                "path": "/" + os.path.relpath(path, filesdir),

                "encoding": "b64",

                "content": content,

                "permissions": octal_mode_string(os.lstat(path).st_mode)

            })

    with open(f"{args.configdir}/user-data.yml") as f:

        sys.stdout.write(f.read())

    sys.stdout.write("write_files: ")

    json.dump(write_files, sys.stdout)

    sys.stdout.write("\n")

if __name__ == "__main__":

    sys.exit(main())