Message:Body is too long and tfcmt could not post comment to PR

[guitarrapc]

Description of issue

When large change PR was create, tfcmt unable to POST changes to PR comment with following error.

POST https://api.github.com/repos/OWNER/REPO/issues/NNN/comments: 422 Validation Failed [{Resource:IssueComment Field:data Code:unprocessable Message:Body is too long (maximum is 65536 characters)}]

Summary

GitHub PR has limitation of PR comment length for 65536 characters, therefore some times tfcmt fail to post result.

Since tfcmt 3.0.0 and above compress plan result it rarely happens. But apply result still contains whole changes and often reached this limit.

Expected behaviour

post changes to PR without error.

Actual behaviour

tfcmt failed to post message. PR shows nothing and user need check GitHub Actions logs.

Other idea

Pulumi also has similar behaviour of Posting changes to GitHub PR comments with comment-on-pr: true

see; https://github.com/pulumi/actions

If message length is over 65536, then it split comment to another comment from terminated line.

[suzuki-shunsuke]

Thank you for your report!

If message length is over 65536, then it split comment to another comment from terminated line.

Oh, it's interesting.

github-comment supports posting substitute comment when it failed to post a too long comment.

https://github.com/suzuki-shunsuke/github-comment#post-a-substitute-comment-when-it-failed-to-post-a-too-long-comment

[suzuki-shunsuke]

Proposal 1: Add short_templates fields

Add short_templates fields, which is a list of templates.
If template is too long, short_templates are used.

e.g.

terraform:
  plan:
    template:
    short_templates:
    - |
      {{template "plan_title" .}}

      {{if .Link}}[CI link]({{.Link}}){{end}}

      {{template "deletion_warning" .}}
      {{template "result" .}}
      {{template "updated_resources" .}}

      {{template "changed_result" .}}
      {{template "warning" .}}
      {{template "error_messages" .}}
    - |
      {{template "plan_title" .}}

      {{if .Link}}[CI link]({{.Link}}){{end}}

      {{template "deletion_warning" .}}
      {{template "result" .}}
      {{template "updated_resources" .}}

      {{template "warning" .}}
      {{template "error_messages" .}}
    - |
      {{template "plan_title" .}}

      {{if .Link}}[CI link]({{.Link}}){{end}}

      {{template "deletion_warning" .}}
      {{template "result" .}}
    when_parse_error:
      template:
      short_templates:
      - "..."
  apply:
    template:
    when_parse_error:
      template:
      short_templates:
      - "..."
    short_templates:
    - |
      {{template "plan_title" .}}

      {{if .Link}}[CI link]({{.Link}}){{end}}

      {{template "deletion_warning" .}}
      {{template "result" .}}
      {{template "updated_resources" .}}

      {{template "changed_result" .}}
      {{template "warning" .}}
      {{template "error_messages" .}}
    - |
      {{template "plan_title" .}}

      {{if .Link}}[CI link]({{.Link}}){{end}}

      {{template "deletion_warning" .}}
      {{template "result" .}}
      {{template "updated_resources" .}}

      {{template "warning" .}}
      {{template "error_messages" .}}
    - |
      {{template "plan_title" .}}

      {{if .Link}}[CI link]({{.Link}}){{end}}

      {{template "deletion_warning" .}}
      {{template "result" .}}

[suzuki-shunsuke]

Proposal 2: Omit long variables automatically

For example, if the variable CombinedOutput is too long, it is omitted as the following automatically.

aws_elb.foo_a: Modifying... [id=foo-a-production]
aws_elb.foo_a: Modifications complete after 2s [id=foo-a-production]

# ...
# ... The maximum length of GitHub Comment is 65536, so the content is omitted by tfcmt.
# ...

Apply complete! Resources: 0 added, 1 changed, 0 destroyed.

[suzuki-shunsuke]

#231

[suzuki-shunsuke]

https://github.com/suzuki-shunsuke/tfcmt/releases/tag/v3.1.0-0

[suzuki-shunsuke]

I've released v3.1.0.
I expect this issue has been solved in almost cases by using the template function wrapCode properly.

[suzuki-shunsuke]

I close this issue, but if you have any question or opinion, please comment.

[guitarrapc]

Sorry for late response. I've updated and seems working correct.
Thank you for prompt update!

[petrsx]

Hi, there seems to be issue

After the substitute, it still post the rest of the plan (unformatted). Pretty lengthy and doesn't seems to hit the limit

[suzuki-shunsuke]

@petr-stupka
Please create a new discussion as this issue was old and already closed.
When you create a discussion, please add a link to this issue.

https://github.com/suzuki-shunsuke/tfcmt/discussions/new?category=support-request

Short answer: I think this is not an issue but an expected behaviour.