macvlan: "failed to set IPv6 gateway: file exists" on network connect #50898
Description
Description
Reported in community Slack, but the user doesn't wish to share details here.
Broadly - with a container attached to one macvlan network, connect it to a second network, disconnect the first network, then re-connect. Some/most of the time, the final re-connect fails with:
Error response from daemon: updating gateway endpoint: failed to set IPv6 gateway: file exists
Reproduce
I'm able to reliably repro the error in a macvlan network connected to a network with a router, using:
docker network create -d macvlan --ipv4=false --ipv6 --subnet fdf0:a9dd:e362:b301::/64 -o parent=enp0s1 mv1
docker network create -d macvlan --ipv4=false --ipv6 --subnet fdf0:a9dd:e362:b364::/64 -o parent=enp0s1 mv2
docker run --rm -d --network mv1 --ip6 fdf0:a9dd:e362:b301::1234 --name c1 busybox sleep infinity
docker network connect mv2 c1 --ip6 fdf0:a9dd:e362:b364::1234
sleep 2
docker network disconnect mv1 c1
sleep 2
docker network connect mv1 c1 --ip6 fdf0:a9dd:e362:b301::1234
But, can't repro in a dev container - I think Docker's gateway assignment is racing IPv6 autoconfig.
Expected behavior
No response
docker version
28.3.3 or current-latest master, on a Debian Trixie VM with a bridged network.docker info
.Additional Info
No response