Python class for configuration files (installation scripts run by root)

ConfigFile.py

#! /usr/bin/env python3
#
#   ConfigFile.py - Jani Tammi <jasata@utu.fi>
#
#   NOTE:   You obviously still need the proper privileges.
#           You cannot run this as a regular user and set
#           owner to be root and expect the .create() to
#           actually manage that.
#           THIS WAS WRITTEN PRIMARILY FOR INSTALLATION
#           SCRIPTS THAT EXECUTE AS ROOT !!
#
import os
import pwd
import grp
import getpass

class ConfigFile:
    """As everything in this script, assumes superuser privileges. Only filename and content are required. User and group will default to effective user and group values on creation time and permissions default to common text file permissions wrxwr-wr- (0o644).
    Properties:
    name            str     Full path and name
    owner           str     Username ('pi', 'www-data', etc)
    group           str     Group ('pi', ...)
    uid             int     User ID
    gid             int     Group ID
    permissions     int     File permissions. Use octal; 0o644
    content         str     This class was written to handle config files

    Once properties and content are satisfactory, write the file to disk:
    myFile = File(...)
    myFile.create(overwrite = True)
    If you wish the write to fail when the target file already exists, just leave out the 'overwrite'.
    """
    def __init__(
        self,
        name: str,
        content: str,
        owner: str = None,
        group: str = None,
        permissions: int = 0o644
    ):
        # Default to effective UID/GID
        owner = pwd.getpwuid(os.geteuid()).pw_name if not owner else owner
        group = grp.getgrgid(os.getegid()).gr_name if not group else group
        self.name           = name
        self._owner         = owner
        self._group         = group
        self._uid           = pwd.getpwnam(owner).pw_uid
        self._gid           = grp.getgrnam(group).gr_gid
        self.permissions    = permissions
        self.content        = content
    def create(self, overwrite = False, createdirs = True):
        if createdirs:
            path = os.path.split(self.name)[0]
            if path:
                os.makedirs(path, exist_ok = True)
        mode = "x" if not overwrite else "w+"
        with open(self.name, mode) as file:
            file.write(self.content)
        os.chmod(self.name, self.permissions)
        os.chown(self.name, self._uid, self._gid)
    def replace(self, key: str, value: str):
        self.content = self.content.replace(key, value)
    @property
    def owner(self) -> str:
        return self._owner
    @owner.setter
    def owner(self, name: str):
        self._uid           = pwd.getpwnam(name).pw_uid
        self._owner         = name
    @property
    def group(self) -> str:
        return self._group
    @group.setter
    def group(self, name: str):
        self._gid           = grp.getgrnam(name).gr_gid
        self._group         = name
    @property
    def uid(self) -> int:
        return self._uid
    @uid.setter
    def uid(self, uid: int):
        self._uid           = uid
        self._owner         = pwd.getpwuid(uid).pw_name
    @property
    def gid(self) -> int:
        return self._gid
    @gid.setter
    def gid(self, gid: int):
        self._gid           = gid
        self._group         = grp.getgrgid(gid).gr_name
    def __str__(self):
        return "{} {}({}).{}({}) {} '{}'". format(
            oct(self.permissions),
            self._owner, self._uid,
            self._group, self._gid,
            self.name,
            (self.content[:20] + '..') if len(self.content) > 20 else self.content
        )

# Recommended way to have config files in your installer script
files = {}
files['nginx.site'] = ConfigFile(
    '/etc/nginx/sites-available/my.domain.com',
    """
Server {
    ...
}
"""
)
files['uwsgi.app'] = ConfigFile(
    '/etc/uwsgi/apps-available/my.domain.com.imi',
    """
[uwsgi]
plugins = python3
...
"""
)


###############################################################################
#
# Simple demonstration
#
if __name__ == '__main__':

    a = ConfigFile(
        "demo.conf",
        "pants {{pants}} pants",
        "www-data"
    )

    # Print current state
    print(a)

    # Do something to it
    a.replace('{{pants}}', '=')
    a.content = "[pants]\n" + a.content
    a.owner = os.getlogin()
    a.group = os.getlogin()
    a.name = "pants.ini"
    print(a)

    # Write to disk
    a.create(overwrite = True)

    # Remove it
    os.remove(a.name)

# EOF