Adding functionality to skip volumes from being backed up. #8

Author: Chris Machler

README.md

@@ -86,7 +86,7 @@ Type "help", "copyright", "credits" or "license" for more information.
 ```
 **We will copy the encoded value and add it as the Lambda environment variable "aws_regions". When copying the encoded value please omit the single quotes in the output (ie. dXMtd2VzdC0yLHVzLWVhc3QtMg==).**
 
-## Add the SNS Topics ARN you want publish as a Lambda environmenet variable "aws_sns_arn"
+## Add the SNS Topics ARN you want publish as a Lambda environment variable "aws_sns_arn"
 
 This is optional environment variable if you want publish any topic, so you might receive email notification
 once backing up was executed.
@@ -95,6 +95,16 @@ once backing up was executed.
 
 Create two functions in Lambda using the Python 2.7 runtime, one for the backup script and one for the cleanup script. I recommend just using the 128 MB memory setting, and adjust the timeout to 10 seconds (longer in a larger environment). Set the event source to be "CloudWatch Events - Schedule" and set the Schedule expression to be a cron expression of your liking i.e. "cron(0 6 * * ? *)" if you want the job to be kicked off at 06:00 UTC, set the cleanup job to run a few minutes later.
 
+## Tagging your EC2 instances to backup
+
+You will need to tag your instances in order for them to be backed up, below are the tags that will be used by the Lambda function:
+
+| Tag Key           | Tag Value                           | Notes |
+| -------------     |:-------------:                      | -----:|
+| Backup            |                                     | Value Not Needed |
+| Retention         | *Number of Days to Retain Snapshot* |  Default is 7 Days|
+|Skip_Backup_Volumes|*volume id(s) in CSV string*         |    List either a single volume-id, or multiple volumes-ids in a Comma Separated Value String |
+
 ## More Info
 
 [Again if you need more details on setting this up please check my blog post.] (http://www.evergreenitco.com/evergreenit-blog/2016/4/19/aws-ebs-backup-job-run-by-lambda)

lambda-ebs-backup.py

@@ -4,6 +4,7 @@
 import base64
 import os
 import json
+import itertools
 
 base64_region = os.environ['aws_regions']
 aws_sns_arn = os.getenv('aws_sns_arn', None)
@@ -61,10 +62,23 @@ def lambda_handler(event, context):
             except IndexError:
                 retention_days = 7
 
+            try:
+                skip_volumes = [
+                    str(t.get('Value')).split(',') for t in instance['Tags']
+                    if t['Key'] == 'Skip_Backup_Volumes']
+            except Exception:
+                pass
+
+            from itertools import chain
+            skip_volumes_list = list(chain.from_iterable(skip_volumes))
+
             for dev in instance['BlockDeviceMappings']:
                 if dev.get('Ebs', None) is None:
                     continue
                 vol_id = dev['Ebs']['VolumeId']
+                if vol_id in skip_volumes_list:
+                    print "Volume %s is set to be skipped, not backing up" % (vol_id)
+                    continue
                 dev_attachment = dev['DeviceName']
                 print "Found EBS volume %s on instance %s attached to %s" % (
                     vol_id, instance['InstanceId'], dev_attachment)