Hiya all :wave:, we have a growing terraform repo ...
# developmentb
bitter-piano-88933
11/01/2021, 9:28 PMHiya all 👋, we have a growing terraform repo over at Foursquare. As it grows, we're facing some interesting dependency problems that feel like a great fit for a tool like Pants. I took a poke around the codebase and found the terraform subsystem, kind of curious what the plans are in that area.
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fast-nail-55400
11/01/2021, 9:33 PMJust linting and formatting for now.
fast-nail-55400
11/01/2021, 9:33 PMi.e.,
terraform fmt👍 1
h
hundreds-father-404
11/01/2021, 9:33 PMcc @early-jelly-55072 who has been really excited about what could come from it
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fast-nail-55400
11/01/2021, 9:33 PMThe existing terraform backend in Pants also does dependency inference for first-party modules (i.e. in repo).
fast-nail-55400
11/01/2021, 9:34 PMso you should be able to run
./pants dependencies some/path/:target_nameh
hundreds-father-404
11/01/2021, 9:35 PMWhat functionality are you envisioning @bitter-piano-88933?
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bitter-piano-88933
11/01/2021, 9:42 PMThe dependency inference for first-party modules is really interesting.
bitter-piano-88933
11/01/2021, 9:44 PMAt the lowest level, I want a tool that correctly determines what terraform needs to be applied if a module it depends on has been updated. All our modules are in the same repo and we don't currently use any 3rd party modules.
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bitter-piano-88933
11/01/2021, 9:45 PMCurrently we have some scripts that attempt to do this. But they're not the most robust peaces of code. We could invest in them more, but we'd be rebuilding something like pants and get none of the more advanced features.
bitter-piano-88933
11/01/2021, 9:46 PMDo you have any plans to support plan/apply down the line?
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hundreds-father-404
11/01/2021, 9:47 PMSweet! So sounds like you'd be looking for project introspection, not having Pants run terraform itself to deploy etc?
I think there was discussion last month about how Pants should probably not go too far down the rabbit hole of Terraform support. It's a non-goal to 100% manage/run Terraform via Pants, you probably will still run it directly. Focus on what Pants excels at instead
hundreds-father-404
11/01/2021, 9:48 PM@bitter-piano-88933 something like this? https://www.pantsbuild.org/docs/advanced-target-selection#running-over-changed-files-with---changed-since
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bitter-piano-88933
11/01/2021, 9:55 PMHum, that's interesting. Yeah, I don't think we have a particular need to run Terraform via Pants. So I think this could work for us. Let me try it out.
bitter-piano-88933
11/01/2021, 9:56 PMOut of curiosity, if you can run validate, that means you're already are dealing with terraform state to some extent. Is there anything that would stop us from extending that to say running plan or apply?
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fast-nail-55400
11/01/2021, 9:58 PMno just the fact that we intentionally don’t want to officially support that use case for now. You are free to use the code in non-merged PR https://github.com/pantsbuild/pants/pull/13023 in your own local repo though if it is useful.
fast-nail-55400
11/01/2021, 9:59 PMalso for
validate.terraformb
bitter-piano-88933
11/01/2021, 10:02 PMMakes sense, thanks for sharing that PR.
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hundreds-father-404
11/01/2021, 10:03 PMBtw this isn't documented b/c it's experimental, but tl;dr to get Terraform working is add to this
pants.toml Copy code
[GLOBAL]
backend_packages = ["pants.backend.experimental.terraform"]./pants tailor./pants fmt path/to/terraform::🙏 1
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bitter-piano-88933
11/01/2021, 10:04 PMI definitely understand the decision made on that PR. But part of me is attracted to the idea of using pants as the single entry point to the tooling in the repo. But apart from aesthetics, no good reason comes to mind. I'll play around with the current iteration and see if I can make a more coherent case.
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h
hundreds-father-404
11/01/2021, 10:06 PMWe're definitely eager to revisit that thinking! And even if it doesn't make sense for core Pants to have more robust Terraform support, we're happy to help with writing a plugin 🙂
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