`tfcmt plan` succeeds without a plan comment when too many resources are changed

[sato-s]

tfaction version

v1.17.0

Overview

When we have a huge plan(> about 60000 lines), tfaction/plan finishes successfully.
But it doesn't provide a plan comment.
I believe this is due to github limitation. But a proper error message would be helpful.

How to reproduce

main.tf

resource "null_resource" "test" {
  count = 20000
}

Expected behaviour

tfaction/plan fails with a proper error message.

Actual behaviour

tfaction/plan finishes successfully.

Note

I understand that we shouldn't make a such huge terraform plan.
But an unintentional misuse of terraform module can be lead to such situation.

[suzuki-shunsuke]

As of tfcmt v3.1.0, tfcmt's wrapCode function omits the comment.

https://github.com/suzuki-shunsuke/tfcmt/releases/tag/v3.1.0

What tfcmt version do you use?
And if you customize the comment template of tfcmt, please check if wrapCode function is used.

[sato-s]

@suzuki-shunsuke
hmm.. that's strange.
I'm using v4.14.7 and not customizing comment template.
(I didn't know there's comment customization.)

aqua.yml

registries:
  - type: standard
    ref: v4.239.0
packages:
//
  - name: suzuki-shunsuke/tfcmt@v4.14.7 # ★
//

GitHub Actions log

time=2025-07-02T09:03:19Z level=info msg=verify a package with slsa-verifier env=linux/amd64 exe_name=tfcmt package_name=suzuki-shunsuke/tfcmt package_version=v4.14.7 program=aqua program_version=2.53.3 registry=standard

[suzuki-shunsuke]

Okay. I could reproduce the issue.

$ tfcmt -v
tfcmt version 4.14.7

resource "null_resource" "test" {
  count = 20000
}

$ tfcmt plan -- terraform plan > /dev/null
ERRO[0011] tfcmt failed                                  error="post a comment: POST https://api.github.com/repos/suzuki-shunsuke/***/issues/296/comments: 422 Validation Failed [{Resource:IssueComment Field:data Code:unprocessable Message:Body is too long (maximum is 65536 characters)}]"

$ echo $?
1

I'll take a look.
But tfcmt outputted the error message and the command failed.
This is different from your report.

[suzuki-shunsuke]

Ah, I see.

You can confirm the output using tfcmt's --output option.

tfcmt plan -output result.md -- terraform plan

List of resources aren't omitted.
So if too many resources are changed, the error occurs.
I think this is unusual.

* Create
  * null_resource.test[0]
  * null_resource.test[1]
  * null_resource.test[2]
  * null_resource.test[3]
  * null_resource.test[4]
  * null_resource.test[5]
  * null_resource.test[6]
  * null_resource.test[7]
  * null_resource.test[8]
  * null_resource.test[9]
  * null_resource.test[10]
  * null_resource.test[11]
...

[suzuki-shunsuke]

I see. If --detailed-exitcode is set, the exit code is 2 even if tfcmt can't post a comment.
This is an expected behaviour.

$ tfcmt plan -- terraform plan --detailed-exitcode
ERRO[0014] tfcmt failed                                  error="post a comment: POST https://api.github.com/repos/suzuki-shunsuke/docs-private/issues/296/comments: 422 Validation Failed [{Resource:IssueComment Field:data Code:unprocessable Message:Body is too long (maximum is 65536 characters)}]"
$ echo $?
2

  -detailed-exitcode         Return detailed exit codes when the command exits.
                             This will change the meaning of exit codes to:
                             0 - Succeeded, diff is empty (no changes)
                             1 - Errored
                             2 - Succeeded, there is a diff

[suzuki-shunsuke]

I think tfcmt should post a comment like the following when it fails to post a comment due to Message:Body is too long.

---

Plan Result (foo)

CI link

Warning

tfcmt couldn't post a comment because the comment body is too long.
So tfcmt posts this comment instead. Please check the log.

Plan: 20000 to add, 0 to change, 0 to destroy.

---