gjalla Add Observability
At companies like Google, Netflix, and Datadog, you can't ship code to production without observability. The question isn't "does it work in tests" — it's "how will the on-call engineer know if it stops working at 3am?" This skill ensures code is instrumented so that problems are detected, diagnosed, and resolved quickly.
Observability has three pillars: logs (what happened), metrics (how much/how fast), and traces (the path a request took). Most production issues need at least two of these to diagnose.
Step 0: Load Production Readiness Context
Before instrumenting code, understand what the team expects for production-ready services.
If gjalla is available, query these tools first:
get_context(scope:architecture) — understand the current monitoring architecture. Are there existing dashboards, alerting systems, or tracing infrastructure you should integrate with?get_context(scope:rules) — check for ADRs about logging standards, metric naming, or alerting policies.
If gjalla is not available, check for existing observability documentation, monitoring configs, or Grafana/Datadog dashboard definitions in the repo.
Structured Logging
Principles
Logs should be structured (JSON), not free-text. Structured logs are searchable, filterable, and parseable by machines. Free-text logs are only useful to humans reading them in real-time.
Every log entry should include:
- timestamp — ISO 8601, always UTC
- level — debug, info, warn, error (use consistently)
- message — human-readable description of what happened
- context fields — request_id, user_id, operation name, relevant parameters
What to Log
- Request boundaries — log when a request arrives and when it completes, with duration
- Decision points — log when the code takes a branch based on data (feature flags, A/B tests, fallbacks)
- External calls — log before and after calls to databases, APIs, queues, with duration and success/failure
- Errors — log the full error with stack trace, input that caused it, and any relevant context
- State changes — log when important domain objects change state (order placed, payment processed)
What NOT to Log
- Sensitive data (passwords, tokens, PII, credit card numbers) — redact or omit
- High-frequency events at INFO level that would create noise (log at DEBUG instead)
- Successful health checks (they just create volume)
Pattern
logger.info("payment_processed", {
order_id: order.id,
amount_cents: order.amount,
currency: order.currency,
payment_method: "card",
duration_ms: elapsed,
})
Metrics
Key Metrics to Instrument
For every service, instrument the RED metrics:
- Rate — requests per second (throughput)
- Errors — error count and error rate (errors / total requests)
- Duration — request latency (p50, p95, p99)
For background jobs and queues, instrument the USE metrics:
- Utilization — how busy is the resource (CPU, memory, queue depth)
- Saturation — how much queued/waiting work exists
- Errors — failure count and rate
Additional Metrics
Beyond RED/USE, consider:
- Business metrics — orders processed, payments completed, users signed up
- Dependency health — latency and error rate for each external dependency
- Cache performance — hit rate, miss rate, eviction rate
- Queue depth — for any async processing
Naming Conventions
Use a consistent naming scheme. A common pattern:
{service}_{component}_{metric}_{unit}
Examples:
api_http_requests_total
api_http_request_duration_seconds
api_database_query_duration_seconds
api_cache_hits_total
api_payment_amount_dollars
Distributed Tracing
For any service that makes calls to other services or databases, add tracing so that a single request can be followed across the entire system.
Implementation
- Generate a trace ID at the entry point of a request
- Propagate the trace ID through all internal calls and to downstream services (via headers)
- Create spans for each significant operation within a request
- Attach relevant tags to spans (user_id, operation, status)
What Gets a Span
- HTTP request handling (the root span)
- Database queries
- Cache lookups
- External API calls
- Message queue publish/consume
- Any operation that takes meaningful time or could fail
Alerting
Alert Design Principles
Alert on symptoms, not causes. Alert when users are affected (high error rate, high latency), not when a specific internal metric changes (CPU at 80%). Symptom-based alerts have fewer false positives and catch problems you didn't anticipate.
Every alert must be actionable. If the on-call engineer can't do anything about it at 3am, it shouldn't page. Make it a dashboard or a low-priority notification instead.
Include runbook links. Every alert should link to a runbook that explains what the alert means, how to diagnose it, and how to mitigate it.
Key Alerts
At minimum, set up alerts for:
- Error rate exceeding baseline (e.g., >1% 5xx for 5 minutes)
- Latency exceeding SLO (e.g., p99 > 500ms for 10 minutes)
- Service availability (health check failures)
- Queue depth growing unboundedly
- Critical dependency unavailable
SLOs (Service Level Objectives)
Define what "good enough" looks like for the service:
- Availability — e.g., 99.9% of requests succeed (non-5xx) over a 30-day window
- Latency — e.g., 99% of requests complete in under 200ms
- Correctness — e.g., 99.99% of transactions produce the correct result
SLOs create an error budget — the acceptable amount of failure. When the error budget is nearly exhausted, the team should prioritize reliability over features.
Output
When adding observability to code, produce:
- Instrumented code — logging, metrics, and tracing added to the implementation
- Dashboard specification — what panels to include on the service dashboard
- Alert definitions — what conditions trigger alerts, with severity levels
- SLO definitions — what the service's reliability targets are
Document the observability setup in a section of the service's README or in a dedicated
docs/observability.md file.
Attestation: Observability as Production Readiness
After adding observability, run the production readiness checklist to verify completeness.
## Observability Attestation
**Criteria met**: [list of observability requirements satisfied]
**Criteria deferred**: [any requirements not yet met, with justification]
**SLOs defined**: [availability, latency, correctness targets]
**Alerts configured**: [list of alerts with runbook links]
**Dashboard created**: [link or spec for the service dashboard]
**Rules respected**: [from get_context(scope="rules") — logging/monitoring ADRs followed]