Configure the disaster recovery contract

You own a regional RAG platform with PostgreSQL, object storage, and vector indexes at primary us-east-1 and recovery us-west-2. The goal is to prove recovery objectives through restore and failover, including data integrity and application correctness rather than infrastructure availability alone. The measurable target is meet a 15-minute recovery point objective and 60-minute recovery time objective; restore the latest consistent PostgreSQL backup, rebuild vector indexes from immutable documents, route 10% then 100% traffic, and keep citation mismatch below 0.1%. The known production tension is hot standby minimizes RTO but doubles substantial model and data cost; rebuildable vector indexes reduce backup complexity but can dominate recovery time for large corpora.

The contract for Disaster recovery must survive a clean checkout. Pin tool and image versions, provide sample inputs, and fail startup on malformed configuration. The service boundary is primary us-east-1 and recovery us-west-2 on a regional RAG platform with PostgreSQL, object storage, and vector indexes. 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:

objectives:
  rpo_minutes: 15
  rto_minutes: 60
recovery_order: [postgres, documents, vector_index, api, dns]
validation:
  database_checksum: required
  citation_mismatch_ratio_max: 0.001
traffic_steps_percent: [10, 50, 100]
abort_on: [checksum_failure, mismatch_budget_exceeded]

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:

terraform -chdir=dr plan -var recovery_region=us-west-2
./dr access verify --role recovery-operator

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 meet a 15-minute recovery point objective and 60-minute recovery time objective; restore the latest consistent PostgreSQL backup, rebuild vector indexes from immutable documents, route 10% then 100% traffic, and keep citation mismatch below 0.1%. Therefore setup must expose backup_age_seconds, backup_restore_duration_seconds, vector_rebuild_progress_ratio, dns_failover_seconds, citation_mismatch_ratio, and recovery_checkpoint_timestamp 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 hot standby minimizes RTO but doubles substantial model and data cost; rebuildable vector indexes reduce backup complexity but can dominate recovery time for large corpora. 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.