Docker / Networking, Ports & Service Connectivity
Check whether a Docker network actually allocates IPv6 addresses
An application can advertise IPv6 support while its container network has no appropriate IPv6 configuration or path.
Environment and inputs: Docker Engine · Compose v2 and Buildx where specified; Linux containers unless noted. Verify daemon context, installed feature support and authorized host or Swarm manager access first.
Start with this check
Confirm the environment and replace sample objects, namespaces, images, paths and hosts with approved targets. Share only relevant, sanitized output. Follow the workload owner’s process for changes.
docker network inspect --format '{{.EnableIPv6}} {{json .IPAM.Config}}' appnetRead the result
The flag and allocation settings describe this network. Application listeners, host routes and upstream connectivity remain separate requirements.
Resolve and verify
Compare the supported daemon and driver configuration with the approved dual-stack design. Correct the missing dependency and test each intended address family.
Before changing production
Do not disable IPv6 across the host or assume an allocated address guarantees external routing and firewall access.