disassociate_first optional flag

[ssolari]

Feature request: There are several use cases where it is desirable that a newly launched instance can be guaranteed to have/steal an address from a pool of existing addresses that may all be attached. Our use cases is rolling docker deployments. #15 is similar.

A flag like "disassociate_first" that will simply perform a disassociate call on the elastic IP http://docs.aws.amazon.com/cli/latest/reference/ec2/disassociate-address.html before trying to acquire the address would seemingly solve our problem. If the flag is false by default it shouldn't be an issue to any existing users.

[adv4000]

Looking for same feature. AWS CLI has flag called --allow-reassociation which is auto deassociate desired IP from any other EC2

aws ec2 associate-address --instance-id=$EC2INSTANCE_ID --allocation-id=$EIPALLOC_ID --allow-reassociation --region=$EC2REGION

[ankitcha]

is there any update on this? If no-one is planning or currently working on it - I could contribute a PR for this. Please let me know. Thanks!

[sebdah]

@ankitcha No active work ongoing for this one. Please submit a PR. I'd be happy to review and merge.

[pmkane]

I need this too. I will submit a PR.

[ghost]

Hi Sebastian,

How I need to run this code in Lambda ? My task is to attach EIP's to newly launched instances, I've setup the Auto Scaling Group and created the Life Cycle Hooks. But how can I put this code in Lambda ?

[pmkane]

With boto3 in master, I've put up a branch that adds support for controlling AllowReassociation via a CLI flag:

https://github.com/pmkane/aws-ec2-assign-elastic-ip/tree/allow_reassociation

Currently, it does not prefer to assign unassociated IPs, in the case that multiple IPs are available for association. This meets our internal requirements, but I imagine could be surprising behavior if someone runs the command without any command-line requirements.

In our own use case, we would only use --allow-reassociation in combination with --valid-ips with a single IP specified. If that fit other folks' requirements too, we could enforce that policy in the tool.

Thoughts @sebdah or others?

[sebdah]

@pmkane I think there is a clear use case for --allow-reassociation (false by default). Your use case with --valid-ips is likely the most common and least dangerous one. But I'm not so sure we should limit the tool to that requirement.

However, maybe a safe behavior would be to enforce --valid-ips in the normal use case and add a --force flag to override that check?

Happy to review / merge etc, so feel free to submit a PR.

[sebdah]

In addition to :point_up:, #40 is adding a flag --tag which should probably also be considered along with --valid-ips.

[pmkane]

Thanks @sebdah , agreed with all. If the PR for #40 is going to be merged soon, I will wait until that happens and then submit a PR. If not, I'll go ahead now.

[sebdah]

:+1: I think you can go ahead :bow:, there's some work to get #40 ready for merging.