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mailinabox/management/backup.py

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#!/usr/local/lib/mailinabox/env/bin/python
# This script performs a backup of all user data:
# 1) System services are stopped.
# 2) STORAGE_ROOT/backup/before-backup is executed if it exists.
# 3) An incremental encrypted backup is made using duplicity.
# 4) The stopped services are restarted.
# 5) STORAGE_ROOT/backup/after-backup is executed if it exists.
import os, os.path, re, datetime, sys
import dateutil.parser, dateutil.relativedelta, dateutil.tz
import rtyaml
from exclusiveprocess import Lock
from utils import load_environment, shell, wait_for_service
def backup_status(env):
# If backups are disabled, return no status.
config = get_backup_config(env)
if config["target"] == "off":
return { }
# Query duplicity to get a list of all full and incremental
# backups available.
backups = { }
now = datetime.datetime.now(dateutil.tz.tzlocal())
backup_root = os.path.join(env["STORAGE_ROOT"], 'backup')
backup_cache_dir = os.path.join(backup_root, 'cache')
def reldate(date, ref, clip):
if ref < date: return clip
rd = dateutil.relativedelta.relativedelta(ref, date)
if rd.years > 1: return "%d years, %d months" % (rd.years, rd.months)
if rd.years == 1: return "%d year, %d months" % (rd.years, rd.months)
if rd.months > 1: return "%d months, %d days" % (rd.months, rd.days)
if rd.months == 1: return "%d month, %d days" % (rd.months, rd.days)
if rd.days >= 7: return "%d days" % rd.days
if rd.days > 1: return "%d days, %d hours" % (rd.days, rd.hours)
if rd.days == 1: return "%d day, %d hours" % (rd.days, rd.hours)
return "%d hours, %d minutes" % (rd.hours, rd.minutes)
# Get duplicity collection status and parse for a list of backups.
def parse_line(line):
keys = line.strip().split()
date = dateutil.parser.parse(keys[1]).astimezone(dateutil.tz.tzlocal())
return {
"date": keys[1],
"date_str": date.strftime("%Y-%m-%d %X") + " " + now.tzname(),
"date_delta": reldate(date, now, "the future?"),
"full": keys[0] == "full",
"size": 0, # collection-status doesn't give us the size
"volumes": int(keys[2]), # number of archive volumes for this backup (not really helpful)
}
code, collection_status = shell('check_output', [
"/usr/bin/duplicity",
"collection-status",
"--archive-dir", backup_cache_dir,
"--gpg-options", "'--cipher-algo=AES256'",
"--log-fd", "1",
*get_duplicity_additional_args(env),
get_duplicity_target_url(config)
],
get_duplicity_env_vars(env),
trap=True)
if code != 0:
# Command failed. This is likely due to an improperly configured remote
# destination for the backups or the last backup job terminated unexpectedly.
raise Exception("Something is wrong with the backup: " + collection_status)
for line in collection_status.split('\n'):
if line.startswith((" full", " inc")):
backup = parse_line(line)
backups[backup["date"]] = backup
# Look at the target directly to get the sizes of each of the backups. There is more than one file per backup.
# Starting with duplicity in Ubuntu 18.04, "signatures" files have dates in their
# filenames that are a few seconds off the backup date and so don't line up
# with the list of backups we have. Track unmatched files so we know how much other
# space is used for those.
unmatched_file_size = 0
for fn, size in list_target_files(config):
m = re.match(r"duplicity-(full|full-signatures|(inc|new-signatures)\.(?P<incbase>\d+T\d+Z)\.to)\.(?P<date>\d+T\d+Z)\.", fn)
if not m: continue # not a part of a current backup chain
key = m.group("date")
if key in backups:
backups[key]["size"] += size
else:
unmatched_file_size += size
# Ensure the rows are sorted reverse chronologically.
# This is relied on by should_force_full() and the next step.
backups = sorted(backups.values(), key = lambda b : b["date"], reverse=True)
# Get the average size of incremental backups, the size of the
# most recent full backup, and the date of the most recent
# backup and the most recent full backup.
incremental_count = 0
incremental_size = 0
first_date = None
first_full_size = None
first_full_date = None
for bak in backups:
if first_date is None:
first_date = dateutil.parser.parse(bak["date"])
if bak["full"]:
first_full_size = bak["size"]
first_full_date = dateutil.parser.parse(bak["date"])
break
incremental_count += 1
incremental_size += bak["size"]
# When will the most recent backup be deleted? It won't be deleted if the next
# backup is incremental, because the increments rely on all past increments.
# So first guess how many more incremental backups will occur until the next
# full backup. That full backup frees up this one to be deleted. But, the backup
# must also be at least min_age_in_days old too.
deleted_in = None
if incremental_count > 0 and incremental_size > 0 and first_full_size is not None:
# How many days until the next incremental backup? First, the part of
# the algorithm based on increment sizes:
est_days_to_next_full = (.5 * first_full_size - incremental_size) / (incremental_size/incremental_count)
est_time_of_next_full = first_date + datetime.timedelta(days=est_days_to_next_full)
# ...And then the part of the algorithm based on full backup age:
est_time_of_next_full = min(est_time_of_next_full, first_full_date + datetime.timedelta(days=config["min_age_in_days"]*10+1))
# It still can't be deleted until it's old enough.
est_deleted_on = max(est_time_of_next_full, first_date + datetime.timedelta(days=config["min_age_in_days"]))
deleted_in = "approx. %d days" % round((est_deleted_on-now).total_seconds()/60/60/24 + .5)
# When will a backup be deleted? Set the deleted_in field of each backup.
saw_full = False
for bak in backups:
if deleted_in:
# The most recent increment in a chain and all of the previous backups
# it relies on are deleted at the same time.
bak["deleted_in"] = deleted_in
if bak["full"]:
# Reset when we get to a full backup. A new chain start *next*.
saw_full = True
deleted_in = None
elif saw_full and not deleted_in:
# We're now on backups prior to the most recent full backup. These are
# free to be deleted as soon as they are min_age_in_days old.
deleted_in = reldate(now, dateutil.parser.parse(bak["date"]) + datetime.timedelta(days=config["min_age_in_days"]), "on next daily backup")
bak["deleted_in"] = deleted_in
return {
"backups": backups,
"unmatched_file_size": unmatched_file_size,
}
def should_force_full(config, env):
# Force a full backup when the total size of the increments
# since the last full backup is greater than half the size
# of that full backup.
inc_size = 0
for bak in backup_status(env)["backups"]:
if not bak["full"]:
# Scan through the incremental backups cumulating
# size...
inc_size += bak["size"]
else:
# ...until we reach the most recent full backup.
# Return if we should to a full backup, which is based
# on the size of the increments relative to the full
# backup, as well as the age of the full backup.
if inc_size > .5*bak["size"]:
return True
if dateutil.parser.parse(bak["date"]) + datetime.timedelta(days=config["min_age_in_days"]*10+1) < datetime.datetime.now(dateutil.tz.tzlocal()):
return True
return False
else:
# If we got here there are no (full) backups, so make one.
# (I love for/else blocks. Here it's just to show off.)
return True
def get_passphrase(env):
# Get the encryption passphrase. secret_key.txt is 2048 random
# bits base64-encoded and with line breaks every 65 characters.
# gpg will only take the first line of text, so sanity check that
# that line is long enough to be a reasonable passphrase. It
# only needs to be 43 base64-characters to match AES256's key
# length of 32 bytes.
backup_root = os.path.join(env["STORAGE_ROOT"], 'backup')
with open(os.path.join(backup_root, 'secret_key.txt'), encoding="utf-8") as f:
passphrase = f.readline().strip()
if len(passphrase) < 43: raise Exception("secret_key.txt's first line is too short!")
return passphrase
def get_duplicity_target_url(config):
target = config["target"]
if get_target_type(config) == "s3":
from urllib.parse import urlsplit, urlunsplit
target = list(urlsplit(target))
# Although we store the S3 hostname in the target URL,
# duplicity no longer accepts it in the target URL. The hostname in
# the target URL must be the bucket name. The hostname is passed
# via get_duplicity_additional_args. Move the first part of the
# path (the bucket name) into the hostname URL component, and leave
# the rest for the path. (The S3 region name is also stored in the
# hostname part of the URL, in the username portion, which we also
# have to drop here).
target[1], target[2] = target[2].lstrip('/').split('/', 1)
target = urlunsplit(target)
return target
def get_duplicity_additional_args(env):
config = get_backup_config(env)
if get_target_type(config) == 'rsync':
# Extract a port number for the ssh transport. Duplicity accepts the
# optional port number syntax in the target, but it doesn't appear to act
# on it, so we set the ssh port explicitly via the duplicity options.
from urllib.parse import urlsplit
try:
port = urlsplit(config["target"]).port
except ValueError:
port = 22
if port is None:
port = 22
return [
f"--ssh-options='-i /root/.ssh/id_rsa_miab -p {port}'",
f"--rsync-options='-e \"/usr/bin/ssh -oStrictHostKeyChecking=no -oBatchMode=yes -p {port} -i /root/.ssh/id_rsa_miab\"'",
]
elif get_target_type(config) == 's3':
# See note about hostname in get_duplicity_target_url.
# The region name, which is required by some non-AWS endpoints,
# is saved inside the username portion of the URL.
from urllib.parse import urlsplit, urlunsplit
target = urlsplit(config["target"])
endpoint_url = urlunsplit(("https", target.hostname, '', '', ''))
args = ["--s3-endpoint-url", endpoint_url]
if target.username: # region name is stuffed here
args += ["--s3-region-name", target.username]
return args
return []
def get_duplicity_env_vars(env):
config = get_backup_config(env)
env = { "PASSPHRASE" : get_passphrase(env) }
if get_target_type(config) == 's3':
env["AWS_ACCESS_KEY_ID"] = config["target_user"]
env["AWS_SECRET_ACCESS_KEY"] = config["target_pass"]
return env
def get_target_type(config):
return config["target"].split(":")[0]
def perform_backup(full_backup):
env = load_environment()
# Create an global exclusive lock so that the backup script
# cannot be run more than one.
Lock(die=True).forever()
config = get_backup_config(env)
backup_root = os.path.join(env["STORAGE_ROOT"], 'backup')
backup_cache_dir = os.path.join(backup_root, 'cache')
backup_dir = os.path.join(backup_root, 'encrypted')
# Are backups disabled?
if config["target"] == "off":
return
# On the first run, always do a full backup. Incremental
# will fail. Otherwise do a full backup when the size of
# the increments since the most recent full backup are
# large.
try:
full_backup = full_backup or should_force_full(config, env)
except Exception as e:
# This was the first call to duplicity, and there might
# be an error already.
print(e)
sys.exit(1)
# Stop services.
def service_command(service, command, quit=None):
# Execute silently, but if there is an error then display the output & exit.
code, ret = shell('check_output', ["/usr/sbin/service", service, command], capture_stderr=True, trap=True)
if code != 0:
print(ret)
if quit:
sys.exit(code)
service_command("php8.0-fpm", "stop", quit=True)
service_command("postfix", "stop", quit=True)
service_command("dovecot", "stop", quit=True)
service_command("postgrey", "stop", quit=True)
# Execute a pre-backup script that copies files outside the homedir.
# Run as the STORAGE_USER user, not as root. Pass our settings in
# environment variables so the script has access to STORAGE_ROOT.
pre_script = os.path.join(backup_root, 'before-backup')
if os.path.exists(pre_script):
shell('check_call',
['su', env['STORAGE_USER'], '-c', pre_script, config["target"]],
env=env)
# Run a backup of STORAGE_ROOT (but excluding the backups themselves!).
# --allow-source-mismatch is needed in case the box's hostname is changed
# after the first backup. See #396.
try:
shell('check_call', [
"/usr/bin/duplicity",
"full" if full_backup else "incr",
"--verbosity", "warning", "--no-print-statistics",
"--archive-dir", backup_cache_dir,
"--exclude", backup_root,
"--volsize", "250",
"--gpg-options", "'--cipher-algo=AES256'",
"--allow-source-mismatch",
*get_duplicity_additional_args(env),
env["STORAGE_ROOT"],
get_duplicity_target_url(config),
],
get_duplicity_env_vars(env))
finally:
# Start services again.
service_command("postgrey", "start", quit=False)
service_command("dovecot", "start", quit=False)
service_command("postfix", "start", quit=False)
service_command("php8.0-fpm", "start", quit=False)
# Remove old backups. This deletes all backup data no longer needed
# from more than 3 days ago.
shell('check_call', [
"/usr/bin/duplicity",
"remove-older-than",
"%dD" % config["min_age_in_days"],
"--verbosity", "error",
"--archive-dir", backup_cache_dir,
"--force",
*get_duplicity_additional_args(env),
get_duplicity_target_url(config)
],
get_duplicity_env_vars(env))
# From duplicity's manual:
# "This should only be necessary after a duplicity session fails or is
# aborted prematurely."
# That may be unlikely here but we may as well ensure we tidy up if
# that does happen - it might just have been a poorly timed reboot.
shell('check_call', [
"/usr/bin/duplicity",
"cleanup",
"--verbosity", "error",
"--archive-dir", backup_cache_dir,
"--force",
*get_duplicity_additional_args(env),
get_duplicity_target_url(config)
],
get_duplicity_env_vars(env))
# Change ownership of backups to the user-data user, so that the after-bcakup
# script can access them.
if get_target_type(config) == 'file':
shell('check_call', ["/bin/chown", "-R", env["STORAGE_USER"], backup_dir])
# Execute a post-backup script that does the copying to a remote server.
# Run as the STORAGE_USER user, not as root. Pass our settings in
# environment variables so the script has access to STORAGE_ROOT.
post_script = os.path.join(backup_root, 'after-backup')
if os.path.exists(post_script):
shell('check_call',
['su', env['STORAGE_USER'], '-c', post_script, config["target"]],
env=env)
# Our nightly cron job executes system status checks immediately after this
# backup. Since it checks that dovecot and postfix are running, block for a
# bit (maximum of 10 seconds each) to give each a chance to finish restarting
# before the status checks might catch them down. See #381.
wait_for_service(25, True, env, 10)
wait_for_service(993, True, env, 10)
def run_duplicity_verification():
env = load_environment()
backup_root = os.path.join(env["STORAGE_ROOT"], 'backup')
config = get_backup_config(env)
backup_cache_dir = os.path.join(backup_root, 'cache')
shell('check_call', [
"/usr/bin/duplicity",
"--verbosity", "info",
"verify",
"--compare-data",
"--archive-dir", backup_cache_dir,
"--exclude", backup_root,
*get_duplicity_additional_args(env),
get_duplicity_target_url(config),
env["STORAGE_ROOT"],
], get_duplicity_env_vars(env))
def run_duplicity_restore(args):
env = load_environment()
config = get_backup_config(env)
backup_cache_dir = os.path.join(env["STORAGE_ROOT"], 'backup', 'cache')
shell('check_call', [
"/usr/bin/duplicity",
"restore",
"--archive-dir", backup_cache_dir,
*get_duplicity_additional_args(env),
get_duplicity_target_url(config),
*args],
get_duplicity_env_vars(env))
def print_duplicity_command():
import shlex
env = load_environment()
config = get_backup_config(env)
backup_cache_dir = os.path.join(env["STORAGE_ROOT"], 'backup', 'cache')
for k, v in get_duplicity_env_vars(env).items():
print(f"export {k}={shlex.quote(v)}")
print("duplicity", "{command}", shlex.join([
"--archive-dir", backup_cache_dir,
*get_duplicity_additional_args(env),
get_duplicity_target_url(config)
]))
def list_target_files(config):
import urllib.parse
try:
target = urllib.parse.urlparse(config["target"])
except ValueError:
return "invalid target"
if target.scheme == "file":
return [(fn, os.path.getsize(os.path.join(target.path, fn))) for fn in os.listdir(target.path)]
elif target.scheme == "rsync":
rsync_fn_size_re = re.compile(r'.* ([^ ]*) [^ ]* [^ ]* (.*)')
rsync_target = '{host}:{path}'
# Strip off any trailing port specifier because it's not valid in rsync's
# DEST syntax. Explicitly set the port number for the ssh transport.
user_host, *_ = target.netloc.rsplit(':', 1)
try:
port = target.port
except ValueError:
port = 22
if port is None:
port = 22
target_path = target.path
if not target_path.endswith('/'):
target_path = target_path + '/'
if target_path.startswith('/'):
target_path = target_path[1:]
rsync_command = [ 'rsync',
'-e',
f'/usr/bin/ssh -i /root/.ssh/id_rsa_miab -oStrictHostKeyChecking=no -oBatchMode=yes -p {port}',
'--list-only',
'-r',
rsync_target.format(
host=user_host,
path=target_path)
]
code, listing = shell('check_output', rsync_command, trap=True, capture_stderr=True)
if code == 0:
ret = []
for l in listing.split('\n'):
match = rsync_fn_size_re.match(l)
if match:
ret.append( (match.groups()[1], int(match.groups()[0].replace(',',''))) )
return ret
else:
if 'Permission denied (publickey).' in listing:
reason = "Invalid user or check you correctly copied the SSH key."
elif 'No such file or directory' in listing:
reason = f"Provided path {target_path} is invalid."
elif 'Network is unreachable' in listing:
reason = f"The IP address {target.hostname} is unreachable."
elif 'Could not resolve hostname' in listing:
reason = f"The hostname {target.hostname} cannot be resolved."
else:
reason = ("Unknown error."
"Please check running 'management/backup.py --verify'"
"from mailinabox sources to debug the issue.")
msg = f"Connection to rsync host failed: {reason}"
raise ValueError(msg)
elif target.scheme == "s3":
import boto3.s3
from botocore.exceptions import ClientError
# separate bucket from path in target
bucket = target.path[1:].split('/')[0]
path = '/'.join(target.path[1:].split('/')[1:]) + '/'
# If no prefix is specified, set the path to '', otherwise boto won't list the files
if path == '/':
path = ''
if bucket == "":
msg = "Enter an S3 bucket name."
raise ValueError(msg)
# connect to the region & bucket
try:
s3 = boto3.client('s3', \
endpoint_url=f'https://{target.hostname}', \
aws_access_key_id=config['target_user'], \
aws_secret_access_key=config['target_pass'])
bucket_objects = s3.list_objects_v2(Bucket=bucket, Prefix=path)['Contents']
backup_list = [(key['Key'][len(path):], key['Size']) for key in bucket_objects]
except ClientError as e:
raise ValueError(e)
return backup_list
elif target.scheme == 'b2':
from b2sdk.v1 import InMemoryAccountInfo, B2Api
from b2sdk.v1.exception import NonExistentBucket
info = InMemoryAccountInfo()
b2_api = B2Api(info)
# Extract information from target
b2_application_keyid = target.netloc[:target.netloc.index(':')]
b2_application_key = urllib.parse.unquote(target.netloc[target.netloc.index(':')+1:target.netloc.index('@')])
b2_bucket = target.netloc[target.netloc.index('@')+1:]
try:
b2_api.authorize_account("production", b2_application_keyid, b2_application_key)
bucket = b2_api.get_bucket_by_name(b2_bucket)
except NonExistentBucket:
msg = "B2 Bucket does not exist. Please double check your information!"
raise ValueError(msg)
return [(key.file_name, key.size) for key, _ in bucket.ls()]
else:
raise ValueError(config["target"])
def backup_set_custom(env, target, target_user, target_pass, min_age):
config = get_backup_config(env, for_save=True)
# min_age must be an int
if isinstance(min_age, str):
min_age = int(min_age)
config["target"] = target
config["target_user"] = target_user
config["target_pass"] = target_pass
config["min_age_in_days"] = min_age
# Validate.
try:
if config["target"] not in {"off", "local"}:
# these aren't supported by the following function, which expects a full url in the target key,
# which is what is there except when loading the config prior to saving
list_target_files(config)
except ValueError as e:
return str(e)
write_backup_config(env, config)
return "OK"
def get_backup_config(env, for_save=False, for_ui=False):
backup_root = os.path.join(env["STORAGE_ROOT"], 'backup')
# Defaults.
config = {
"min_age_in_days": 3,
"target": "local",
}
# Merge in anything written to custom.yaml.
try:
with open(os.path.join(backup_root, 'custom.yaml'), encoding="utf-8") as f:
custom_config = rtyaml.load(f)
if not isinstance(custom_config, dict): raise ValueError # caught below
config.update(custom_config)
except:
pass
# When updating config.yaml, don't do any further processing on what we find.
if for_save:
return config
# When passing this back to the admin to show the current settings, do not include
# authentication details. The user will have to re-enter it.
if for_ui:
for field in ("target_user", "target_pass"):
if field in config:
del config[field]
# helper fields for the admin
config["file_target_directory"] = os.path.join(backup_root, 'encrypted')
config["enc_pw_file"] = os.path.join(backup_root, 'secret_key.txt')
if config["target"] == "local":
# Expand to the full URL.
config["target"] = "file://" + config["file_target_directory"]
ssh_pub_key = os.path.join('/root', '.ssh', 'id_rsa_miab.pub')
if os.path.exists(ssh_pub_key):
with open(ssh_pub_key, encoding="utf-8") as f:
config["ssh_pub_key"] = f.read()
return config
def write_backup_config(env, newconfig):
backup_root = os.path.join(env["STORAGE_ROOT"], 'backup')
with open(os.path.join(backup_root, 'custom.yaml'), "w", encoding="utf-8") as f:
f.write(rtyaml.dump(newconfig))
if __name__ == "__main__":
if sys.argv[-1] == "--verify":
# Run duplicity's verification command to check a) the backup files
# are readable, and b) report if they are up to date.
run_duplicity_verification()
elif sys.argv[-1] == "--list":
# List the saved backup files.
for fn, size in list_target_files(get_backup_config(load_environment())):
print(f"{fn}\t{size}")
elif sys.argv[-1] == "--status":
# Show backup status.
ret = backup_status(load_environment())
print(rtyaml.dump(ret["backups"]))
print("Storage for unmatched files:", ret["unmatched_file_size"])
elif len(sys.argv) >= 2 and sys.argv[1] == "--restore":
# Run duplicity restore. Rest of command line passed as arguments
# to duplicity. The restore path should be specified.
run_duplicity_restore(sys.argv[2:])
elif sys.argv[-1] == "--duplicity-command":
print_duplicity_command()
else:
# Perform a backup. Add --full to force a full backup rather than
# possibly performing an incremental backup.
full_backup = "--full" in sys.argv
perform_backup(full_backup)
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