kube merge configs

kube_merge_configs.py

"""Merge or unmerge kubernetes config files.

Usage:
    kube_merge_configs.py [options] <conf_yaml>

Options:
    --unmerge, -u     Remove the input file from your main config
    --noop            Don't write the main config, dump to stdout
"""


import os

import yaml
from docopt import docopt


MERGE_KEYS = ("clusters", "contexts", "users")


def config_plus(config, new_config):
    """Add the new config values to the existing config."""

    for key in MERGE_KEYS:
        for item in new_config[key]:
            if item not in config[key]:
                config[key].append(item)


def config_minus(config, new_config):
    """Remove the new config values from the existing config."""

    for key in MERGE_KEYS:
        for item in new_config[key]:
            config[key].remove(item)


def main():
    """Command line entry point."""

    args = docopt(__doc__, version="kube_merge_configs.py 0.0.1")
    if not os.path.isfile(args["<conf_yaml>"]):
        raise SystemExit("conf_yaml {} not found".format(args["<conf_yaml>"]))

    try:
        with open(args["<conf_yaml>"], "r") as openconf:
            new_conf = yaml.load(openconf.read())
    except Exception as error:
        raise SystemExit("could not load new config: {!r}".format(error))

    conf_path = os.path.join(os.path.expanduser("~"), ".kube", "config")
    try:
        with open(conf_path, "r") as openconf:
            config = yaml.load(openconf.read())
    except Exception as error:
        raise SystemExit("could not load default config: {!r}".format(error))

    if args["--unmerge"]:
        config_minus(config, new_conf)
    else:
        config_plus(config, new_conf)

    config_str = yaml.dump(config, default_flow_style=False, indent=2).strip()
    if args["--noop"]:
        print(config_str)
    else:
        with open(conf_path, "w") as openconf:
            openconf.write(config_str)
        print("merged {} into kube config at {}".format(
            args["<conf_yaml>"],
            conf_path,
        ))


if __name__ == "__main__":
    main()