Enabling JSON output for Terraform instead of writing the HCL syntax …

[mccare]

Enabling output of JSON instead of HCL v1, writing kubernetes.tf.json instead of kubernetes.tf. JSON can be consumed by terraform 0.12. ( https://www.terraform.io/docs/configuration/syntax-json.html )

Tried it on AWS and GCE test cluster.

If you enable this feature, you need to delete the previously generated kubernetes.tf file. Also, this feature will require minimum version of terraform 0.12.

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[tanjunchen]

/ok-to-test

[rifelpet]

This is great! I was working on adding native HCL2 support but it will require touching every task's terraform struct to add hcl tags which is much more invasive than i was hoping, so having json support is a good middle ground.

Are you able to test the output with both 0.11 and 0.12? If it only works with 0.12 we may want to make the feature flag's name specifically call that out.

I believe we still run into the issue with the default route and VPC additional CIDR block names that start with digits, is that correct? We'll still need to conditionally rename those somehow.

we'll want to mention this in docs/terraform.md as well.

Can you add an integration test for this? The test would go in cmd/kops/integration_test.go and the input and output files would go in tests/integration/update_cluster. I think we may run into an issue with enabling this feature flag for a specific test (the GCE tests in that file already do that of you need an example). if we run tests in parallel other tests may use the enabled flag which would break them... hoping that's not the case but we'll see.

[mccare]

On first sight it seems that terraform 0.11 supports .tf.json files. Release notes for 0.12.0 list in the improvement section that

In prior versions, certain Terraform configuration features did not function as expected or were not usable via the JSON-based forms.

But I couldn't find what features this were exactly. (and if they are used by kops)

So I would restrict JSON output to terraform 0.12 (also creating the required_version). In addition, I could fail generating json output if kubernetes.tf is present in the target directory (since terraform seems combines the two and then complains)

Naming issues are not resolved by using JSON as format (so a name beginning with a number is still invalid).

I'll have a look at the integration tests.

[mccare]

Added one integration test. You have to unset the feature flag after the test otherwise the test suite would fail.

I needed to add (yet) another parameter to the runTestAWS to check for the kubernetes.tf.json file (instead of kubernetes.tf). Are there other options? (one struct for parameters?) I'm new to go.

[rifelpet]

Ok, I renamed the route resource and tested terraform plan with both 0.11 and 0.12 and they both succeeded. This feature flag wont be fully functional until we get the route and vpc additional cidr resources renamed though. I'll try to test the applys sometime soon but if someone is willing to do that, that would be great.

[johngmyers]

/test pull-kops-verify-staticcheck

[mccare]

Added an error if the kubernetes.tf file is still present (no JSON file will be generated then). The error message contains a note to read the release notes.

For moving state (for the rename)

• created a cluster with terraform 0.11
• applied the PR Update Terraform resource names to be 0.12 compatible. #7957 to kops
• removed kubernetes.tf file
• ran kops with the JSON flag.
• moved the resource for the default route:
  terraform011 state mv aws_route.0-0-0-0--0 aws_route.route-0-0-0-0--0
• terraform plan --out planfile (0.12) did say "nothing to do"

Moving the state with terraform 0.12 did not work since the name was invalid.

[rifelpet]

@mccare can you rebase to pull in the resource renaming that merged as well as fix the integration_test conflict?

[mccare]

@rifelpet fixed the tests and rebased the commit.

[rifelpet]

I tested this on a terraform plan and it works perfectly.

I also tested this on an existing cluster and kops binary: generate terraform 0.11 output, plan and apply it with 0.11. Then use this branch to generate 0.12 output, plan and apply that with 0.12 and confirm no changes. Everything looks great! This is a big next step 🎉

I'm thinking of adding a test that downloads terraform and actually runs a terraform validate against some of our integration test expected outputs, but thatll happen in a separate PR.

/approve
/lgtm

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