Automatic creation of snapshots using AWS Lambda

Question

I have completed the automatic creation of snapshots using the following link :

https://blog.powerupcloud.com/2016/02/15/automate-ebs-snapshots-using-lambda-function/

As written in the code, filtering is done based on tags of VMs. Instead of creating a VM with a Backup or backup tag, I want to create snapshots of all except for some names.

I do not want to add extra tags to VMs. Instead, I want to write an if condition in my filters. I would provide the names of my Test VMs and if the VM tag matches that, snapshot would not be created. If it does not match, snapshots have to be created. Can I do that?

Ex : I have four VMs in my account.

VM 1 --> Prod1,
VM 2 --> Prod2,
VM 3 --> Prod3, 
VM 4 --> Test1.

Acc to example, I need to be able to write an if condition which includes my test VM tag 'Test1'. If the tag matches this, the snapshot should not be created. If it does not match, snapshots have to be created.

So, for doing this, how should I change my code?

Answer 1

The piece of code that picks up which VMs need to be backed up is this:

reservations = ec.describe_instances(
        Filters=[
            {'Name': 'tag-key', 'Values': ['Backup', 'True']},
        ]
    ).get(
        'Reservations', []
    )

As you can see, it uses boto's describe_instances and a filter limits the number of instances that will be processed. If you would like to backup everything except for those which are non-prod in your environment, you should consider tagging your non-prod instances with something like Backup=NO.

Answer 2

You just need to create a tag for all your three servers with key 'Backup'. The script is filtering the instances on the key names only.

Answer 3

To backup all servers except those marked with a tag:

• Get a list of all servers
• Get a list of servers with the 'do not backup' flag and remove them from the first list
• Do the backup

It will require two calls to describe_instances().