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snapshot.py
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snapshot.py
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import arrow # http://crsmithdev.com/arrow/
import boto3 # http://boto3.readthedocs.io/en/latest/reference/services/
import json
import argparse
from random import randint
from multiprocessing.dummy import Pool as ThreadPool
from datetime import datetime
ec2 = None
ec2_resource = None
cliargs = None
def create_snapshot(volume_name, volume_id):
"""
Creates a snapshot of the volume id we pass in.
This will also tag the snapshot with the volume's Name tag
contents.
"""
if cliargs.verbose:
print "Will snapshot '%s' and tag it with '%s'" % (volume_id, volume_name)
response = ec2.create_snapshot(VolumeId=volume_id, Description=volume_name)
if response:
ec2.create_tags(Resources=[response["SnapshotId"]], Tags=[{"Key": "Name", "Value": volume_name}])
def process_volume(args):
'''
Processes a single volume. This is designed to be used in a multi-threaded manner.
args = return value from ec2.describe_volumes()
See: http://boto3.readthedocs.io/en/latest/reference/services/ec2.html#EC2.Client.describe_volumes
'''
volume_name = ""
for tag in args["Tags"]:
if tag["Key"] == "Name": volume_name = tag["Value"]
backup_frequency = None
backup_retention = None
# We check for the frequency and retention tags here
# because we want to detect problems here before making
# more calls to AWS and wasting time.
#
# If the tags don't exist, then we can't work with the
# volume.
for tag in args["Tags"]:
if tag["Key"] == "snapshotbackup_frequency":
backup_frequency = int(tag["Value"]) # minutes
if cliargs.verbose:
print("Backup frequency: %s" % backup_frequency)
if tag["Key"] == "snapshotbackup_retention":
backup_retention = int(tag["Value"]) # days
if cliargs.verbose:
print("Backup retention: %s" % backup_retention)
if not backup_retention or not backup_frequency:
if cliargs.verbose:
print "Volume '%s' has a 'snapshotbackup' tag, but no frequency or retention tags. Taking no action." % args["VolumeId"]
return
# Get a list of all the snapshots for this volume
# We use a tag key filter on the volume-id as they're the only snapshots we're intested in
response = ec2.describe_snapshots(Filters=[{"Name": "volume-id", "Values": [args["VolumeId"]]}])
if response:
oldest_snapshot = None
latest_snapshot = None
script_inception = arrow.get(2017, 1, 1)
# Loop over the snapshots and work out which is the oldest/latest
for snapshot in response["Snapshots"]:
# If neither are defined yet, then the first snapshot
# is both the latest and oldest (for now)
if not oldest_snapshot and not latest_snapshot:
if cliargs.verbose:
print("Oldest and latest snapshot set to %s" % snapshot["SnapshotId"])
oldest_snapshot = snapshot
latest_snapshot = snapshot
continue
# After we loop around, does the snapshot we're looking at
# now exist in past relative to the last one we marked as
# oldest? If so, it's the new oldest snapshot
if snapshot["StartTime"] < oldest_snapshot["StartTime"]:
if cliargs.verbose:
print("Older snapshot found: %s" % snapshot["SnapshotId"])
oldest_snapshot = snapshot
continue
# As above, but this time looking for the latest snapshot
if snapshot["StartTime"] > latest_snapshot["StartTime"]:
if cliargs.verbose:
print("Latest snapshot found: %s" % snapshot["SnapshotId"])
latest_snapshot = snapshot
continue
# If this volume has no snapshots at all, then there
# won't be an oldest or latest, so we just create a snapshot
# and move on
if not oldest_snapshot and not latest_snapshot:
create_snapshot(volume_name, args["VolumeId"])
return
# If we do have an oldest or latest snapshot then we
# can begin working out what to do based on dates.
# I use the arrow library as it makes dealing with dates easier.
# We essentially take the latest snapshot's datetime and advance it
# forward by backup_frequency minutes. That way, if the current UTC
# time is in the PAST relative to the advanced time, then we know
# we're NOT due to take a snapshot. Once $now moves into the future
# beyond the latest snapshot's time, the latest snapshot is now
# too old and a new one is needed.
now = arrow.utcnow()
latest_snapshot_future = arrow.get(latest_snapshot["StartTime"])
latest_snapshot_future = latest_snapshot_future.replace(minutes=+backup_frequency)
if cliargs.verbose:
print("Latest snapshot future UTC (Current UTC: %s): %s" % (arrow.get(latest_snapshot["StartTime"]), latest_snapshot_future))
if latest_snapshot_future < now:
create_snapshot(volume_name, args["VolumeId"])
# Same as above with the latest snapshot, except now we're
# working out if the oldest snapshot is too old and should
# be deleted.
oldest_snapshot_future = arrow.get(oldest_snapshot["StartTime"])
oldest_snapshot_future = oldest_snapshot_future.replace(days=+backup_retention)
if cliargs.verbose:
print("Oldest snapshot future UTC (Current UTC: %s): %s" % (arrow.get(oldest_snapshot["StartTime"]), oldest_snapshot_future))
if oldest_snapshot_future < now:
# We ignore any snapshots prior to the inception of
# this script's creation: 2016-11
if oldest_snapshot["StartTime"] < script_inception:
if cliargs.verbose:
print "Snapshot before inception date. Ignoring."
return
if cliargs.verbose:
print "Will delete old snapshot id %s (%s)" % (oldest_snapshot["SnapshotId"], oldest_snapshot["StartTime"])
response = ec2.delete_snapshot(SnapshotId=oldest_snapshot["SnapshotId"])
def main():
global ec2, ec2_resource, cliargs
parser = argparse.ArgumentParser(fromfile_prefix_chars="@")
# Tags related flags
parser.add_argument(
"--tag",
help="The tag to filter on and use to find targets for snapshots",
default="snapshotbackup"
)
parser.add_argument(
"--tag-value",
help="The tag value to filter on and determine if the volume should be backed up",
default="true"
)
parser.add_argument(
"--tag-frequency",
help="The tag for determining snapshot frequency",
default="snapshotbackup_frequency"
)
parser.add_argument(
"--tag-retention",
help="The tag for determining snapshot retention",
default="snapshotbackup_retention"
)
# AWS related flags
parser.add_argument("--profile",
help="AWS Profile to use in ~/.aws/credentials",
default="default"
)
parser.add_argument("--region",
help="AWS region to work with",
default="ap-southeast-2"
)
parser.add_argument("--access-key",
help="AWS API access key ID",
default=""
)
parser.add_argument("--access-key-secret",
help="AWS API secret key ID",
default=""
)
# Snapshot.py related flags
parser.add_argument("--verbose",
"-v",
help="Verbose output for debugging purposes",
action="store_true",
default=False
)
cliargs = parser.parse_args()
boto_args = {
"region_name": cliargs.region,
"profile_name": cliargs.profile,
"aws_access_key_id": cliargs.access_key,
"aws_secret_access_key": cliargs.access_key_secret,
}
aws_session = boto3.session.Session(**boto_args)
ec2 = aws_session.client("ec2")
ec2_resource = aws_session.resource("ec2")
# We fetch a list of volumes in EC2. All of them, but we filter them based
# on having a tag with the key of `--tag`'s value. This saves us having to
# do that processing ourselves.
response = ec2.describe_volumes(Filters=[{
"Name": "tag:%s" % cliargs.tag,
"Values": [cliargs.tag_value]
}])
if len(response["Volumes"]) > 0:
# We create a pool of 4 threads and then we loop over the list,
# mapping each item in the list against the process_volume() function.
# This is a standard map() as per functional programming.
pool = ThreadPool(4)
pool.map(process_volume, response["Volumes"])
else:
if cliargs.verbose:
print "No volumes found."
if __name__ == "__main__":
main()