matrix-ops/global/overlay/etc/puppet/setup_cosmos_modules

#!/usr/bin/env python3
""" Write out a puppet cosmos-modules.conf """

import hashlib
import os
import os.path
import socket
import sys

try:
    from configobj import ConfigObj
    os_info = ConfigObj("/etc/os-release")
except (IOError, ModuleNotFoundError):
    os_info = None

try:
    fqdn = socket.getfqdn()
    hostname = socket.gethostname()
except OSError:
    host_info = None
else:
    domainname = '.'.join([x for x in fqdn.split('.')[1:]])
    hostname = fqdn.split('.')[0]
    environment = 'test' if 'test' in fqdn.split('.') else 'prod'
    service = fqdn.split('.')[1]
    host_info = {
        "domainname": domainname,
        "environment": environment,
        "fqdn": fqdn,
        "hostname": hostname
    }

def get_file_hash(modulesfile):
    """
    Based on https://github.com/python/cpython/pull/31930: should use
    hashlib.file_digest() but it is only available in python 3.11
    """
    try:
        with open(modulesfile, "rb") as fileobj:
            digestobj = hashlib.sha256()
            _bufsize = 2**18
            buf = bytearray(_bufsize)  # Reusable buffer to reduce allocations.
            view = memoryview(buf)
            while True:
                size = fileobj.readinto(buf)
                if size == 0:
                    break  # EOF
                digestobj.update(view[:size])
    except FileNotFoundError:
        return ""

    return digestobj.hexdigest()


def get_list_hash(file_lines):
    """Get hash of list contents"""

    file_lines_hash = hashlib.sha256()
    for line in file_lines:
        file_lines_hash.update(line)

    return file_lines_hash.hexdigest()


def create_file_content(modules):
    """
    Write out the expected file contents to a list so we can check the
    expected checksum before writing anything
    """
    file_lines = []
    file_lines.append("# Generated by {}\n".format(  # pylint: disable=consider-using-f-string
        os.path.basename(sys.argv[0])).encode("utf-8"))
    for key in modules:
        file_lines.append("{0:11} {1} {2} {3}\n".format(  # pylint: disable=consider-using-f-string
            key,
            modules[key]["repo"],
            modules[key]["upgrade"],
            modules[key]["tag"],
        ).encode("utf-8"))

    return file_lines


def main():
    """Starting point of the program"""

    modulesfile: str = "/etc/puppet/cosmos-modules.conf"
    modulesfile_tmp: str = modulesfile + ".tmp"

    modules: dict = {
        "apparmor": {
            "repo": "https://github.com/SUNET/puppet-apparmor.git",
            "upgrade": "yes",
            "tag": "sunet-2*",
        },
        "bastion": {
            "repo": "https://github.com/SUNET/puppet-bastion.git",
            "upgrade": "yes",
            "tag": "sunet-2*",
        },
        "nagioscfg": {
            "repo": "https://github.com/SUNET/puppet-nagioscfg.git",
            "upgrade": "yes",
            "tag": "sunet-2*",
        },
        "sunet": {
            "repo": "https://github.com/SUNET/puppet-sunet.git",
            "upgrade": "yes",
            "tag": "stable-2*",
        },
        "ufw": {
            "repo": "https://github.com/SUNET/puppet-module-ufw.git",
            "upgrade": "yes",
           "tag": "sunet-2*",
        },
        "matrix": {
            "repo": "https://platform.sunet.se/matrix/matrix-puppet.git",
            "upgrade": "yes",
            "tag": "stable-2*",
        }
    }

    # When/if we want we can do stuff to modules here
    if host_info:
        if host_info["environment"] == "test":
            modules["sunet"]["tag"] = "testing-2*"
            modules["matrix"]["tag"] = "testing-2*"
    #   if host_info["fqdn"] == "k8sw1.matrix.test..sunet.se":
    #       modules["sunet"]["tag"] = "mandersson-test*" 
    # Build list of expected file content
    file_lines = create_file_content(modules)

    # Get hash of the list
    list_hash = get_list_hash(file_lines)

    # Get hash of the existing file on disk
    file_hash = get_file_hash(modulesfile)

    # Update the file if necessary
    if list_hash != file_hash:
        # Since we are reading the file with 'rb' when computing our hash use 'wb' when
        # writing so we dont end up creating a file that does not match the
        # expected hash
        with open(modulesfile_tmp, "wb") as fileobj:
            for line in file_lines:
                fileobj.write(line)

        # Rename it in place so the update is atomic for anything else trying to
        # read the file
        os.rename(modulesfile_tmp, modulesfile)


if __name__ == "__main__":
    main()