Invalid yaml workflows due to PyYaml's default 80-character width limit

[jaseemabid]

1. This bug can be reproduced using pure Argo YAML

• Yes 👉 Please report a bug to the Argo Workflows GitHub 👈
• No

2. I have searched for existing issues

• Yes

3. This bug occurs in Hera when...

• exporting to YAML
• submitting to Argo
• running on Argo with the Hera runner
• other:

Bug report

Describe the bug

Hera's to_yaml() method uses PyYAML's default 80-character line width, which breaks long template expressions across multiple lines, making them syntactically invalid for Argo Workflows.

To Reproduce

  from hera.workflows import WorkflowTemplate
  from hera.workflows import models as m

  # Create a workflow with a long template expression
  wt = WorkflowTemplate(
      name="test-yaml-wrapping",
      workflow_metadata=m.WorkflowMetadata(
          annotations={
              "workflows.argoproj.io/description": "ref={{= sprig.trunc(7, workflow.parameters.gh-ref) }}, push={{ workflow.parameters.push }}"
          }
      )
  )

  print("Current output (breaks template expression):")
  print(wt.to_yaml())

  print("\nWith width=160 (keeps template expression intact):")
  print(wt.to_yaml(width=160))

Expected behavior
Template expressions should remain on a single line to maintain their syntactic validity:

  workflowMetadata:
    annotations:
      workflows.argoproj.io/description: ref={{= sprig.trunc(7, workflow.parameters.gh-ref) }}, push={{ workflow.parameters.push }}

Actual behavior

Template expressions are broken across lines, making them invalid:

  workflowMetadata:
    annotations:
      workflows.argoproj.io/description: ref={{= sprig.trunc(7, workflow.parameters.gh-ref)
        }}, push={{ workflow.parameters.push }}

Additional context

We could set a reasonable default width (like 160) to fix the issue? Would you like me to create a PR @elliotgunton?

  def dump(*args, **kwargs) -> str:
      # Set some default options if not provided by the user
      kwargs.setdefault("default_flow_style", False)
      kwargs.setdefault("sort_keys", False)
      kwargs.setdefault("width", 160)  # 👈🏼 👈🏼 👈🏼
      return _yaml.dump(*args, **kwargs)

[elliotgunton]

That's an interesting edge case, and sensible workaround. I think for a fix to the codebase though the full/correct solution would be to post-process the YAML and check for broken expressions, which I think would be to just check for matching {{ / }} on the same line (lol), and squash them back if not valid (checking line by line, so not necessarily the whole thing on one line).

Some test cases:

Inputs:

test-case-1: {{some brackets}} # unchanged
test-case-2: {{some
    brackets}} # squash to one line
test-case-3: {{some
    brackets}} {{more
    brackets}} # squash to one line
test-case-4: {{some
    brackets}}
    {{more
    brackets}} # squash to 2 lines

Outputs:

test-case-1: {{some brackets}} # unchanged
test-case-2: {{some brackets}} # squashed to one line
test-case-3: {{some brackets}} {{more brackets}} # squashed to one line
test-case-4: {{some brackets}}
    {{more brackets}} # squashed to 2 lines

[jaseemabid]

I'm horrified to report that according to yaml spec, these 2 files are exactly identical and this is probably a bug in the way argo wf parse the yaml lol. My 🐰 🕳️ are indeed getting deeper.

See Section 7.3. Flow Scalar Styles

❯ /bin/cat config1.yaml
title: "Simple Configuration"
description: "Simple Configuration"

❯ /bin/cat config2.yaml
title: "Simple Configuration"
description: "Simple
Configuration"

❯ dyff between config1.yaml config2.yaml
     _        __  __
   _| |_   _ / _|/ _|  between config1.yaml
 / _' | | | | |_| |_       and config2.yaml
| (_| | |_| |  _|  _|
 \__,_|\__, |_| |_|   returned no differences
        |___/

[elliotgunton]

🤯 great 😂

[jaseemabid]

Argo WF UI is indeed broken, but pasting a screenshot here without all the internal company info is a bit too much hassle.