How do you scale a service and override config per environment in Compose?
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Quick Answer
Use --scale for stateless replicas, and layer compose.override.yml or -f files for per-environment settings.
Detailed Answer
docker compose up --scale web=3 runs three replicas of a stateless service (behind a proxy/load balancer). Compose merges docker-compose.yml with docker-compose.override.yml automatically, or you pass multiple -f files (base + prod) to override images, replicas, and env per environment.
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Interview Tip
Explain the automatic override.yml merge behavior.
docker-composescalingoverrides