Multi-zone EC2 instance implementation is not possible about terraform-aws-ec2-instance

[Dogers]

Looks like no as the subnet_id var is only a string? It'd need to be a list along with an element() switch in the module to pick the subnet based on count.index.
This would break backwards compatibility but should be easy enough to add - any thoughts @antonbabenko ?

[antonbabenko]

There is no need to change anything in this module, because one EC2 instance can be created in a single subnet, so as @Dogers is saying you have to provide subnet_id it as a string (use element(..., count.index)).

Going to close #30.

Please let me know if I am missing something completely obvious.

[levmichael3]

@Dogers @antonbabenko Thank you first of all for the real fast response.
Secondly - my motivation was to create a cluster with dynamic number of nodes which is MZed.
Each node should have been created in a different zone dynamically so the code footprint was too long, calling the same module per zone. I gad to use Scaling group instead of this EC2 module.

[Dogers]

@antonbabenko at the moment this module can only create X instances in subnet A per call of the module. The request here is to say create X instances over subnets A, B, C.

[antonbabenko]

Yes, I understand that but I don't like this way because it hides the logic of creation of instances internally.

As a maintainer, I constantly have to think about what will happen when a user wants to create instances with different arguments (eg, security groups) depending on which subnet it is running.

Also, as a good practice and in most of the cases, you should be able to replace this module with terraform-aws-autoscaling module when you need to deploy across several subnets.

[Dogers]

Can understand the first point and fair enough if that's the way you want it to go. Happy to keep a custom copy in this case :)

But for the second, SGs don't depend on subnets, as they're contained in the VPC rather than the subnet..?

We've got a need for this currently as we have some things that unfortunately can't be just brought up by an ASG.

[antonbabenko]

Right, example with security group was far-fetched :)

[github-actions]

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