backup_nginx_symlinks.py

#!/usr/bin/env python
'''
backup_nginx_symlinks
---------------------
Create or overwrite a file called `/opt/restore-nginx-symlinks.sh` if
the file is writable. Change the directory by setting the LP_BACKUPS
environment variable to something other than /opt.

Usually you must run this as root.

Running the generated `sh` file will remove all symlinks (not files) in
/etc/nginx/sites-enabled and re-add symlinks that were there on the
last run of `backup-nginx-symlinks`.
'''
from __future__ import print_function
import sys
import locale
import os
# from datetime import datetime
import time

if __name__ == "__main__":
    SUBMODULE_DIR = os.path.dirname(os.path.realpath(__file__))
    MODULE_DIR = os.path.dirname(os.path.dirname(SUBMODULE_DIR))
    sys.path.insert(0, os.path.dirname(MODULE_DIR))

from linuxpreinstall import (
    echo0,
)
from linuxpreinstall.logging2 import getLogger

logger = getLogger(__name__)

LC_ALL = os.environ.get('LC_ALL')
if LC_ALL is not None:
    locale.setlocale(locale.LC_ALL, LC_ALL)
else:
    # datetime.now().strftime("%c")
    # BEFORE: 'Fri May 27 07:20:46 2022'
    locale.setlocale(locale.LC_ALL, "en_US.UTF-8")
    # AFTER:  'Fri 27 May 2022 07:20:54 AM '
# dt_fmt = "%c"  # based on locale (see `else` case above)
dt_fmt = "%a %d %b %Y %H:%M:%S %p %Z"
# ^ match linux 'date' command output in US locale, like
#   'Fri 27 May 2022 07:14:49 AM EDT'
# ^ BUT instead of "EDT" it is blank for datetime.now(),
#   even after setlocale!
# date_s = datetime.now().strftime(dt_fmt)
date_s = time.strftime("%c", time.localtime(time.time()))

EUID = os.geteuid()
if EUID != 0:
    logger.error(
        "You must be root to run {} but EUID is {}."
        .format(sys.argv[0], EUID))
    sys.exit(1)

LP_BACKUPS = os.environ.get("/opt")
if LP_BACKUPS is None:
    LP_BACKUPS = "/opt"
restore_path = os.path.join(LP_BACKUPS, "restore-nginx-symlinks.sh")
enabled_path = "/etc/nginx/sites-enabled"
heading = '''#!/bin/bash
# DO NOT EDIT THIS FILE DIRECTLY:
# It is generated and will be overwritten
# by the next run of "{}".

'''.format(sys.argv[0])

pre_restore_deletes_or_errors = '''echo "* removing symlinks in {ep}:"
for site in `ls {ep}`
do
    DEST="`readlink {ep}/$site`"
    if [ "$DEST" != "" ]; then
        echo "* removing symlink. Undo via: ln -s $DEST {ep}/$site"
        rm "{ep}/$site"
    else
        echo "# skipping 'rm' for real file \\"{ep}/$site\\""
    fi
done
'''

restore_or_error = '''DEST="{dest}"
if [ ! -f "$DEST" ]; then
    echo "Error: Restore files before running $0 to try to fix missing:"
    echo "# ln -s $DEST {ep}/{site}"
    code=1
else
    echo "* running 'ln -s \\"$DEST\\" \\"{ep}/{site}\\"'"
    ln -s "$DEST" "{ep}/{site}"
fi
'''


def main():
    with open(restore_path, 'w') as outs:
        outs.write(heading)
        outs.write(pre_restore_deletes_or_errors.format(
            ep=enabled_path,
        ))
        outs.write("code=0\n")
        subs = os.listdir(enabled_path)
        count = 0
        for site in subs:
            subPath = os.path.join(enabled_path, site)
            if os.path.islink(subPath):
                count += 1
        if count < 1:
            outs.write(
                'echo "There are no symlink(s)'
                ' to restore for sites-enabled"\n'
            )
        else:
            outs.write(
                'echo "{} symlink(s) to restore in sites-enabled:"\n'
                ''.format(count)
            )
        for site in subs:
            subPath = os.path.join(enabled_path, site)
            if os.path.islink(subPath):
                dest = os.readlink(subPath)
                outs.write(restore_or_error.format(
                    dest=dest,
                    ep=enabled_path,
                    site=site,
                ))
                # if [ $? -ne 0 ]; then exit 1; fi
            else:
                outs.write('# skipping "ln -s" for real file "{}"\n'
                           ''.format(subPath))
        echo0("{} is complete {}.".format(restore_path, date_s))
        outs.write("echo \"got nginx symlinks from {}\"\n"
                   "".format(date_s))
        outs.write("exit $code\n")
    return 0


if __name__ == "__main__":
    sys.exit(main())