command/fmt: support formatting multiple files

[zimbatm]

All the code infrastructure was there to support formatting multiple
files already.

This makes terraform fmt more flexible and also compliant with the
treefmt formatted spec

Fixes numtide/treefmt#97

[codecov]

Codecov Report

Merging #28191 (a648ade) into main (bc38623) will decrease coverage by 1.29%.
The diff coverage is 16.66%.

Impacted Files	Coverage Δ
command/fmt.go	58.85% <16.66%> (-14.80%)	⬇️
terraform/eval_error.go	33.33% <0.00%> (-16.67%)	⬇️
terraform/transform_vertex.go	45.45% <0.00%> (-11.69%)	⬇️
terraform/transform_local.go	63.63% <0.00%> (-11.37%)	⬇️
terraform/node_provisioner.go	71.42% <0.00%> (-10.39%)	⬇️
states/statefile/version0.go	33.33% <0.00%> (-9.53%)	⬇️
helper/hashcode/hashcode.go	66.66% <0.00%> (-8.34%)	⬇️
backend/remote/colorize.go	55.55% <0.00%> (-8.09%)	⬇️
plans/plan.go	40.00% <0.00%> (-8.00%)	⬇️
registry/response/terraform_provider.go	37.50% <0.00%> (-7.96%)	⬇️
... and 654 more

[zimbatm]

codecov is complaining because the added doc is untested :)

[zimbatm]

ping?

[mloughran]

Some more context and justification for this PR from my perspective: treefmt allows dramatically speeding up repository formatting by only attempting to format files that have changed. The current interface to terraform fmt, while working great standalone, is too restrictive to support this use-case. This seems like a shame!

[zimbatm]

rebased to fix the merge conflict

[zimbatm]

rebased to fix the merge conflicts

[flokli]

Ping @jbardin. It'd be really nice if this could go in!

[zimbatm]

/cc @teamterraform

[hashicorp-cla]

All committers have signed the CLA.

[aldoborrero]

This feature is useful to have!

[mloughran]

Some more justification for this PR: Currently the only way to run terraform via treefmt is it to use a wrapper script (e.g. see https://github.com/numtide/treefmt/blob/master/treefmt.toml#L77)

Unfortunately, the startup speed of terraform fmt means that running it separately for each file is very slow. On my project (64 terraform files) this is already 23s. Output from treefmt:

[INFO]: #terraform: 64 files processed in 23.24s

Whereas

terraform fmt -recursive  0.48s user 0.90s system 83% cpu 1.659 total

This makes treefmt + terraform just about acceptable for local use cases (hopefully the files don't change much, and treefmt only runs on changed files), but it's a deal-breaker for use cases such as checking formatting in CI.

[crw]

Hi @zimbatm, apologies for the late reply. We should be able to review this within a few weeks. Thanks for your patience.

[alisdair]

Thanks for this contribution! This looks like a nice improvement. There are a couple of things to fix before we can merge:

• There's a merge conflict due to some recent help text changes. Can you rebase and fix that?
• We need to update the website docs to note the new functionality. Can you update the docs file here to describe how terraform fmt works after your changes?

[codecov-commenter]

Codecov Report

Merging #28191 (b070abd) into main (21228e1) will increase coverage by 1.46%.
The diff coverage is 16.66%.

❗ Current head b070abd differs from pull request most recent head 7a9ccc0. Consider uploading reports for the commit 7a9ccc0 to get more accurate results

Impacted Files	Coverage Δ
command/fmt.go	59.78% <16.66%> (-16.61%)	⬇️
terraform/graph_builder_eval.go	0.00% <0.00%> (-100.00%)	⬇️
terraform/node_provider_eval.go	0.00% <0.00%> (-100.00%)	⬇️
terraform/ui_output_callback.go	0.00% <0.00%> (-100.00%)	⬇️
repl/format.go	11.42% <0.00%> (-87.63%)	⬇️
configs/provider_meta.go	0.00% <0.00%> (-83.34%)	⬇️
command/version.go	0.00% <0.00%> (-71.24%)	⬇️
internal/getproviders/http_mirror_source.go	0.00% <0.00%> (-68.93%)	⬇️
internal/providercache/installer_events.go	42.85% <0.00%> (-57.15%)	⬇️
command/console_interactive.go	0.00% <0.00%> (-48.15%)	⬇️
... and 776 more

[zimbatm]

rebased!

• The code didn't change
• I re-did the doc, copying some of the text from the website
• Renamed PATH... to [target...] to better follow the other commands.
• Updated the cmd and website descriptions to be more in sync.

[alisdair]

Thanks, this is great!

[github-actions]

Reminder for the merging maintainer: if this is a user-visible change, please update the changelog on the appropriate release branch.

[github-actions]

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