Join a Docker Compose service to a pre-existing (external) network that Compose should not create
domain: docs.docker.com/reference/compose-file/networks/#external · 5 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Declare the network as external under top-level `networks:`: `networks: sharednet: external: true` (optionally `name: actual-network-name`).
Attach one or more services to it: `services: app: networks: [sharednet, default]`.
Compose then assumes the network already exists (created outside this project) and does not manage its lifecycle; it errors if the network is missing at up time.
When combined, `external: true` only allows the `name` attribute on the entry — all other settings are invalid.
With `external: true`, Compose looks up the network by the literal name (from `name:` or the key) and will NOT create it — run `docker network create sharednet` first if it doesn't exist.
You cannot set driver, ipam, or driver_opts on an external network — Compose rejects the file.
The default `com.docker.compose.network` label is not applied to external networks.
A service can join both an external network and the project's default network for mixed connectivity.
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