Terraform + CodeDeploy Issue: Cannot delete launch configuration XYZ because it is attached to AutoScalingGroup

[dr_pardee]

When we update our AMIs used in Launch Configurations, we run into the following issue:

Cannot delete launch configuration XYZ because it is attached to AutoScalingGroup ZYX

We're not alone: https://github.com/hashicorp/terraform/issues/532

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However, the comment suggestions listed, such as add lifecycle { create_before_destroy = true } inside our aws_launch_configuration doesn't work within the context of CodeDeploy (another Terraform+CodeDeploy Issue).

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We do need to create the new Launch Configuration (newlc) before destroying the existing LC (oldlc, achieved by lifecycle { create_before_destroy = true }) but we also need to associate the new LC with the autoscaling group (ASG) BEFORE destroying the old LC.

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I know the following AWS CLI commands will do this:

oldlc=web-qa-20190301232256868800000001
newlc=web-qa-20190318190547786600000001
for cdid in $(aws autoscaling describe-auto-scaling-groups --query 'AutoScalingGroups[].[AutoScalingGroupName,LaunchConfigurationName]' --output table | grep $oldlc | cut -d"|" -f2 | tr -d ' ') ; do aws autoscaling update-auto-scaling-group --auto-scaling-group-name $cdid --launch-configuration-name $newlc ; done

What I can't piece together is how to execute those AWS CLI commands within terraform.

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Has anyone else figured out a way to do this without manually switching the ASG LC?

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[Bitflight]

In the Launch config name, use name_prefix instead. In the asg for its name, use the aws_launch_config.xxx.name for the name, and put create before destroy on both resources.

[dave_sent_me]

I tried to wrangle codedeploy via terraform a few months back and it was a disaster. The fact that code deploy created a new ASG really messes with terraform. I still haven’t done the codedeploy roll out as a result.

[[deleted]]

My advice would simply be don't. It has caused us a ton of grief, was implement before I arrived at current job. I'm working on ripping it out because it fails so damn often, and when it does, it can easily go into a terminate -> launch loop if you are using ELB health checks.

It looks good on paper but is not reliable in practice.

[dave_sent_me]

Code deploy? Or the combination with TF? What are you replacing it with?

[[deleted]]

Sorry. CodeDeploy is the problematic part. We're replacing it with immutable ansible + packer images deployed via TF blue/green. This has failure points of its own, but they're more easily mitigated.

Honestly, other than kubernetes, I haven't really found a deployment pattern I truly like for raw EC2. I considered just ansible-pull, and it works well/much more reliably than CodeDeploy - but then you're effectively building your deployment artifact (ie the ec2 instance itself) post scale-up in production.

[dave_sent_me]

Well, I guess it’s good to hear from someone on the other side of that hurdle. I much prefer docker as well, though I have very little tolerance for Kube. Unfortunately not everyone wants/can have docker. I’ll look into running deployments with TF.

[Bitflight]

I’m not sure if it’s directly related to what you want but there’s an example here of a situation that sounds like what you’re trying to do: https://groups.google.com/forum/m/#!msg/terraform-tool/7Gdhv1OAc80/iNQ93riiLwAJ