Configure the service-level objectives contract

You own an AI support-answer service at POST /v1/support/answer. The goal is to turn user-visible availability and latency into measurable SLIs, an error budget, and release decisions that resist vanity averages. The measurable target is 99.5% good-event availability over 28 days and 95% of eligible answers with time-to-first-token below 1.2 seconds; exclude authenticated client 4xx but count malformed upstream output and timeout fallbacks as bad events. The known production tension is a strict SLO protects users but can freeze valuable releases; broad eligibility makes gaming harder but may charge product experiments against the reliability budget.

The contract for Service-level objectives must survive a clean checkout. Pin tool and image versions, provide sample inputs, and fail startup on malformed configuration. The service boundary is POST /v1/support/answer on an AI support-answer service. Before starting dependencies, list required ports, identities, secrets, storage, and cleanup steps. Use synthetic credentials and redacted fixtures; production tokens do not make a staging lab more realistic.

Create the configuration as a reviewed artifact:

groups:
- name: support-answer-slo
  rules:
  - record: slo:availability:ratio_rate5m
    expr: sum(rate(sli_events_total{indicator="availability",outcome="good"}[5m]))
      / sum(rate(sli_events_total{indicator="availability"}[5m]))
  - alert: SupportAnswerFastBurn
    expr: slo:availability:burn_rate1h > 14.4 and slo:availability:burn_rate5m > 14.4
    for: 2m

For every field, document type, valid range, default, reload behavior, and failure behavior. Numbers are incomplete without units. A timeout of 40 could mean milliseconds or seconds; a ratio of 0.005 could be a fraction or percentage. Reject unknown keys so a typo cannot silently select a permissive default. If live reload is supported, expose a configuration revision in telemetry and keep the previous valid revision for rollback.

Run the setup workflow:

docker compose up -d prometheus alertmanager answer-api
curl -fsS localhost:9090/api/v1/rules | jq .data.groups[].name

The expected result is not merely exit code zero. Confirm the process identity, dependency reachability, effective configuration, and one health or introspection response. Then restart the component and prove durable state remains correct. Run the setup twice to expose non-idempotent creation, conflicting ports, or duplicate policy entries. Capture the exact versions in the evidence bundle.

The production objective remains 99.5% good-event availability over 28 days and 95% of eligible answers with time-to-first-token below 1.2 seconds; exclude authenticated client 4xx but count malformed upstream output and timeout fallbacks as bad events. Therefore setup must expose sli_events_total{indicator,outcome}, slo_error_budget_remaining_ratio, slo_burn_rate, time_to_first_token_seconds, and alert delivery timestamps before meaningful traffic arrives. Query each metric by its stable labels and verify an idle system is distinguishable from a broken scraper. Generate one event and check that the relevant counter changes by exactly one. Reject high-cardinality labels and ensure sensitive configuration values are redacted from startup logs.

Model a bad configuration: remove one required field, set one threshold just outside its range, and reference an unavailable dependency. Each case should fail predictably, explain the field, and avoid partial state. Next, apply the previous good revision and time recovery. A rollback that requires undocumented shell history is not a rollback plan.

The central design tension is a strict SLO protects users but can freeze valuable releases; broad eligibility makes gaming harder but may charge product experiments against the reliability budget. Record the chosen default, its operational owner, and a date for reevaluation. Complete setup only after a teammate can run it from the repository instructions, produce the same effective configuration, and cleanly tear it down without affecting shared environments.