Validate watcher yaml format

[jaydeluca]

Noticed copilot is complaining that we are not producing valid yaml format:

https://github.com/open-telemetry/opentelemetry-ecosystem-explorer/pull/828/changes#r3607442967

[vanshika2720]

Hey @jaydeluca , I would love to work on this...
Could you assign it to me???

[ThyTran1402]

Hi,

Can I take a look at this issue?

Thank you!

[jaydeluca]

thanks both of you for your interest in this issue. I opened it to first figure out if this warning even matters, since everything is working. If someone wants to start by investigating whether this should be fixed, or whether it's fine, that's the best starting point

[vanshika2720]

@jaydeluca I investigated this further and found that the warning appears to be a false positive. The generated watcher YAML parses successfully with multiple YAML parsers (PyYAML and ruamel.yaml), and yamllint only reports style-related issues, not syntax errors. It looks like Copilot is misinterpreting PyYAML's default formatting (folded scalars/non-indented sequences), which is valid YAML. Based on this, I don't think a functional fix is needed, though we could consider a formatting change in the generator if we want to reduce future warnings.

[bhuvan-somisetty]

Hey @jaydeluca, following up on what vanshika2720 found above - went and tracked down where this is actually coming from. It's in ecosystem-automation/collector-watcher/src/collector_watcher/inventory_manager.py (lines 149 and 478), the yaml.dump(..., default_flow_style=False, sort_keys=False, allow_unicode=True) calls.

Turns out PyYAML just doesn't indent list items under their parent key by default unless you subclass the Dumper and override increase_indent. It's a known quirk with PyYAML, not actually broken YAML - so this lines up with what vanshika2720 said, Copilot's flagging something that's valid.

Also noticed the same dump call (no custom indent handling) shows up in watcher-common, js-instrumentation-watcher, and dotnet-instrumentation-watcher too, so it's not just the collector watcher.

If it's still worth cleaning up for readability even though nothing's actually broken, I can put together a PR with a small shared Dumper subclass so all four watchers get consistent indentation. Let me know and happy to take it on if so.