"attachable" flag for non-overlay network


I see --attachable flag in options of docker network create. And I konw that if I want to make a overlay network can be used by standalone containers, I need to add --attachable flag.

But I don’t know if this flag is valid for other networks. For example, I try to add the --attachable flag to the bridge network. In the docker network inspect view, the attachable value becomes true. But regardless of whether to add this flag, I can attach the container to the bridge network.

I would like to ask about the effect of this flag on other networks, or is there any relevant document recommendation (sorry I didn’t find it myself)

I would appreciate for any help and advice.
Best wishes!

According to the documentation


you can use the --attachable flag for local drivers like bridge, but the network needs to be in swarm scope.

Adding the attachable flag to a simple local bridge without swarm scope would not make any difference, although I don’t see it directly stated in the docs, but the flag is only mentioned in the context of swarm. I guess it just doesn’t give you an error message, but simply ignored.