fettle: Command for Claude Code

$ARGUMENTS refers to any text the user typed after the slash command.

Run a Production Readiness Review (PRR) checklist for the target service.

Procedure

1. Determine service name. Use $ARGUMENTS if provided. If not provided, derive the name from the current working directory basename.

2. Create output directory. Create .fettle/ in the current working directory if it doesn't already exist:

   mkdir -p .fettle
   

3. Copy the ops-review template. Locate the bundled template and write it to .fettle/ops-review-{name}.md, replacing {SERVICE_NAME} with the service name and {DATE} with today's date:

   python3 -c "from fettle._resources import templates_dir; print(templates_dir() / 'ops-review.md')"
   

   Read the file at the printed path.

4. Run automated checks on the codebase. Use Grep and Glob to scan for operational readiness indicators and pre-fill the template sections:

   Deployment (Section 1):

   • Search for systemd service files: Glob for *.service files in the project or /etc/systemd/.
   • Search for Docker configs: Glob for Dockerfile, docker-compose.yml, docker-compose.yaml, compose.yml, compose.yaml.
   • Search for SIGTERM, signal.signal, signal_handler, GracefulExit, shutdown patterns in Python files.
   • Search for hardcoded secrets: patterns like password=, api_key=, secret= followed by string literals (not env var lookups).
   • If service file or Docker config found, mark deployment item as [PASS]. Otherwise [FAIL].
   • If graceful shutdown handling found, mark that item as [PASS]. Otherwise [?].
   • If hardcoded secrets found, mark secrets item as [FAIL] with file:line. Otherwise [PASS].

   Monitoring (Section 2):

   • Search for health check patterns: health, heartbeat, ping, /healthz, /health in route definitions or scripts.
   • Search for watchdog patterns: watchdog, WatchdogSec, sd_notify, systemd.watchdog.
   • If health check found, mark as [PASS]. Otherwise [FAIL].
   • If watchdog found, mark as [PASS]. Otherwise [?].

   Alerting (Section 3):

   • Search for alerting/notification patterns: telegram, slack, send_message, smtp, email, alert, notify, webhook in source files.
   • If notification mechanism found, mark as [PASS] with details. Otherwise [FAIL].
   • Mark dedup/severity and escalation items as [?] for manual review.

   Resilience (Section 4):

   • Search for timeout patterns: httpx.Timeout, timeout=, socket.settimeout, aiohttp.*timeout, requests.*timeout.
   • Search for retry patterns: tenacity, @retry, backoff, retry_on, max_retries, Retry(.
   • Search for circuit breaker patterns: circuit_breaker, CircuitBreaker, pybreaker.
   • If timeouts found, mark timeout item as [PASS]. Otherwise [FAIL].
   • If retry with backoff found, mark retry item as [PASS]. Otherwise [FAIL].
   • If circuit breaker found, mark as [PASS]. Otherwise [?].

   Data Safety (Section 5):

   • Search for backup patterns: backup, dump, pg_dump, sqlite3 .backup, shutil.copy.
   • Search for atomic write patterns: tempfile, os.rename, os.replace, Path.replace.
   • If backup mechanism found, mark as [PASS]. Otherwise [?].
   • If atomic writes found, mark as [PASS]. Otherwise [?].

   Capacity (Section 6):

   • Search for resource limit patterns: ulimit, MemoryLimit, LimitNOFILE, --memory, mem_limit.
   • Search for log rotation: RotatingFileHandler, TimedRotatingFileHandler, logrotate, maxBytes.
   • If log rotation found, mark as [PASS]. Otherwise [FAIL].
   • Mark remaining items as [?].

   Security (Section 7):

   • Search for secrets in source: hardcoded API keys, passwords, tokens (string literals assigned to variables named key, secret, password, token).
   • Search for os.getenv or environ for secret loading (good practice).
   • Search for input validation: pydantic, validator, validate, sanitize.
   • If secrets loaded from env, mark as [PASS]. If hardcoded, mark as [FAIL] with file:line.
   • If input validation found, mark as [PASS]. Otherwise [?].