Docker Compose Explained: Why Your App Boots Before Its Database Is Ready
One YAML file starts your app, its database and the wiring between them. It also has a famous trap, because the app can come up first. Here is the…
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Voltage · Hardware Editor
The short answer
Docker Compose lets you describe a multi-container app in one file, compose.yaml, and start all of it with docker compose up. The file has one required part, services, and optional networks,…
compose.yaml: services are required; networks, volumes, configs and secrets are optional; the top-level version key is obsolete
depends_on: controls start and stop order, but not readiness, unless you add condition: service_healthy plus a healthcheck
Data: named volumes survive docker compose down; they are removed only with the -v flag
Moving on: Docker documents Compose for single hosts; multiple machines are when you look at Swarm or Compose Bridge to Kubernetes
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Docker Compose Explained: Why Your App Boots Before Its Database Is Ready