Playgrounds Logs

[MODE:DIALOG] Read-only, idempotent. Tier: brownfield.

One-shot service log fetch. Maps to Rails GET /api/playgrounds/:id/logs/:service (Api::PlaygroundsController#logs) which enqueues PlaygroundLogSnapshotJob (so reading logs from a remote Marquee doesn't block the request thread); the SDK polls the resulting request_id and returns the final payload.

When to use

• Debug a specific service's startup error.
• Read a known-bounded chunk (tail lines) before deciding whether to follow.
• Pair with fibe_playgrounds_debug for full context (debug surfaces names; logs surface causes).

When NOT to use

• Need to wait for a pattern to appear — use fibe_playgrounds_logs_follow.
• Need debug summary, not raw logs — use fibe_playgrounds_debug.

Inputs

Field	Type	Required	Notes
playground_id	number	one of	Numeric ID
playground_identifier	string	one of	Numeric ID or slug-safe name
service	string	yes	Compose service name (must exist in the Playspec)
tail	number	no	Lines to fetch; default 50, clamped to Docker::LogFetcher::MAX_TAIL_LINES

Output

{
  "playground_id": 42,
  "service": "web",
  "tail": 200,
  "logs": "...",          // raw mixed stdout+stderr
  "stdout": "...",        // present when fetcher separates streams
  "stderr": "...",
  "fetched_at": "2026-..."
}

Schema varies slightly by Marquee Docker version; the logs field is always populated.

Behavior

1. Rails validates service against the Playspec's declared services (rejects unknown).
2. Clamps tail to [1, MAX_TAIL_LINES].
3. Enqueues PlaygroundLogSnapshotJob (the worker SSHes to the Marquee and runs docker logs --tail <N>).
4. Returns request_id + status_url; SDK polls.

Gotchas

• "Service not found" usually means a typo — service names come from the Playspec's services[*].name, not always the Compose service name (Fibe sometimes prefixes/normalizes).
• Marquee unreachable → polling eventually returns an error envelope. Re-check Marquee status.
• Logs may be truncated by Docker's own log driver (max-size etc.); tail is best-effort.
• Container restarts reset stdout/stderr buffers — recent crashes may have logs that no longer exist.

Related

• fibe_playgrounds_debug — names + ports + per-service status.
• fibe_playgrounds_logs_follow — live streaming with pattern matching.
• fibe-debug skill — broader troubleshooting recipes.