refactor: Log subprocess stderr as WARN (#1563)

[rmccorm4]

Overview:

Cherry-pick #1563 into release 0.3.1

Summary by CodeRabbit

• Style
  • Updated logging to display certain subprocess messages as warnings instead of errors for improved clarity.

[rmccorm4]

@CodeRabbit full review

[coderabbitai]

✅ Actions performed

Full review triggered.

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Walkthrough

The logging level for messages read from a subprocess's standard error stream in subprocess.rs was changed from error to warn. An explanatory comment was added to clarify the reasoning behind this adjustment and to indicate that a more refined solution may be considered in the future.

Changes

File(s)	Change Summary
launch/dynamo-run/src/subprocess.rs	Changed stderr logging from error to warn; added explanatory comment about logging behavior

Possibly related PRs

• fix: dynamo-run change python subprocess from debug to info #1484: Adjusts logging levels for subprocess stream output in the same file, focusing on stderr handling.
• refactor: Log subprocess stderr as WARN #1563: Changes subprocess stderr logging from error to warn with a similar comment, addressing the same concern.

Poem

A warning, not an error, now appears,
When subprocesses whisper in our ears.
For stderr's not always a sign of dread—
Sometimes just a library talking instead!
So with a gentle hop and a thoughtful paw,
The rabbit logs with wisdom, not with awe.
🐇✨

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

launch/dynamo-run/src/subprocess.rs (1)

101-105: Stderr blanket-downgraded to WARN – consider content-based escalation

Changing every stderr line to tracing::warn! removes the false-positive noise, but it will also demote real stack traces and fatal errors to WARN, making them easy to miss in production dashboards / alerting pipelines.

A low-impact middle ground is to route lines that obviously contain error markers (ERROR, Traceback, etc.) back to error!, leaving the rest at warn!:

-            tracing::warn!("{}", strip_log_prefix(&line));
+            if line.contains("ERROR")
+                || line.contains("Error")
+                || line.contains("Traceback")
+            {
+                tracing::error!("{}", strip_log_prefix(&line));
+            } else {
+                tracing::warn!("{}", strip_log_prefix(&line));
+            }

This keeps the current noise reduction while preserving critical visibility for genuine failures.
Feel free to adjust the heuristics or gate them behind a feature flag if you’re concerned about performance or false matches.

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📥 Commits

Reviewing files that changed from the base of the PR and between 9d6252c and 41ae938.

📒 Files selected for processing (1)

• launch/dynamo-run/src/subprocess.rs (1 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (2)

• GitHub Check: Build and Test - vllm
• GitHub Check: pre-merge-rust (.)