schedule-ebs-snapshot-backups.py

# Copyright 2015 Ryan S Brown
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""
This function creates scheduled snapshots and adds tags: BackupTag and
DeleteOn - the current day formatted as YYYY-MM-DD.
"""

import boto3
import datetime
import os

ec = boto3.client("ec2")

if "BACKUP_TAG" in os.environ:
    tag = os.environ["BACKUP_TAG"]
else:
    tag = "Backup"

if "BACKUP_RETENTION" in os.environ:
    ret_period = os.environ["BACKUP_RETENTION"]
else:
    ret_period = "7"

# calculate retention in minutes
if "d" in ret_period:
    retention = 24 * 60 * int(ret_period.split("d")[0])
elif "h" in ret_period:
    retention = 60 * int(ret_period.split("h")[0])
else:
    retention = int(ret_period)


def lambda_handler(event, context):
    reservations = ec.describe_instances(
        Filters=[{"Name": "tag:%s" % tag, "Values": ["true", "yes", "1"]}]
    ).get("Reservations", [])

    instances = sum([[i for i in r["Instances"]] for r in reservations], [])

    print "Found %d instances with tag %s that need backing up" % (len(instances), tag)

    for instance in instances:
        for dev in instance["BlockDeviceMappings"]:
            if dev.get("Ebs", None) is None:
                continue
            vol_id = dev["Ebs"]["VolumeId"]
            try:
                instance_name = [i for i in instance["Tags"] if i["Key"] == "Name"][0][
                    "Value"
                ]
            except IndexError:
                instance_name = instance["InstanceId"]

            print "Found EBS volume %s on instance %s (%s)" % (
                vol_id,
                instance["InstanceId"],
                instance_name,
            )

            snap = ec.create_snapshot(VolumeId=vol_id)

            delete_date = datetime.datetime.utcnow() + datetime.timedelta(
                minutes=retention
            )
            delete_fmt = delete_date.strftime("%Y-%m-%d-%H-%M")

            print "Retaining snapshot %s of volume %s from instance %s at %s" % (
                snap["SnapshotId"],
                vol_id,
                instance["InstanceId"],
                delete_fmt,
            )

            ec.create_tags(
                Resources=[snap["SnapshotId"]],
                Tags=[
                    {"Key": "BackupTag", "Value": tag},
                    {"Key": "DeleteOn", "Value": delete_fmt},
                    {"Key": "Name", "Value": instance_name},
                ],
            )