Terragrunt Stacks compatibility

[hndrewaall]

I am trying to get a proof of concept repo working with Digger and the new Terragrunt Stacks RFC.

So far I have run into two main issues:

1. In order to generate projects, I think I need Digger to invoke terragrunt stack generate before it traverses the tree. So far I have had to use manual mode, as I haven't found another way to have the runner call stack generate before Digger begins to parse. Would it be possible to add configuration options to execute arbitrary scripts before project generation?
2. Digger seems to want to invoke terragrunt show on the generated plans, but for this to work, I need to be able to inject the --experiment stacks stack run prefix to the invocation. Is it possible to add extra args that will be used for ALL invocations of Terragrunt, even those not explicitly referenced in the workflow plan config?

[motatoes]

Hi @hndrewaall !! Wow interesting. Note I didn't look in depth at the RFC but going of your two questions regarding digger

RE no.1 Unfortunately we don't support yet overriding the command that early. Would you consider running it as a step in the github action workflow prior to digger step? or they need to be run for every single terragrunt module?

RE no.2 that is correct and it uses that to count number of resources changed. unfortunately we only currently support extra_args for plan: and apply: phases and don't have a way to override the show command. What you could do for a quick test is to update the args here to append the values mentioned. So perhaps something like this would work after update:

args := []string{command}
args = append(args, arg...)
args = append(args, "--experiment", "stacks", "stack", "run")

And you can reference your digger fork as an action step in an attempt to try it out

Happy to support in any way to get your POC repo working!

[hndrewaall]

Thanks so much for the prompt reply!

RE 1: That's what I've been doing (check my linked PR), but is it possible to work with the cloud version (not manual mode) this way? AFAICT the webhooks fire but my job is never invoked, though possibly I am doing something else wrong, as I haven't yet tried it with "vanilla" Terragrunt or plain TF. I've updated my PR to use the backend again and you can see what I mean.

RE 2: I'll give it a shot, thanks!

[hndrewaall]

Update:

RE 1: I tried vendoring the generated Terragrunt files, and I do now get Digger Cloud to parse as expected (though still with errors since it doesn't have the --experiment stacks flags). So I'm guessing that to get this working locally I'll have to self host.

RE 2: This worked! I'm going to try opening a PR once I clean it up and can add some tests.

[motatoes]

Hi @hndrewaall nice, looking forward to it!