Add --mac-address flag to set custom MAC addresses for containers #753
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| return networkIds.enumerated().map { item in | ||
| guard item.offset == 0 else { | ||
| return AttachmentConfiguration(network: item.element, options: AttachmentOptions(hostname: containerId)) | ||
| return AttachmentConfiguration(network: item.element, options: AttachmentOptions(hostname: containerId, macAddress: item.offset == 0 ? macAddress : nil)) |
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(disclaimer: I'm not a maintainer and I'm not requesting a change, just interested in this feature because I'm implementing an adjacent feature to --network in #751)
Do you know how docker or podman handle this if there are multiple networks? I think if you do something like --network net-1 --network net-2 --mac-address ff:ff:ff:ff:ff:ff this will set the MAC on net-1.
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Thanks for the question! Yes, multiple --network flags are supported with a single --mac-address flag. I tested this and here's the behavior:
container run --network net-1 --network net-2 --mac-address 02:42:ac:11:00:02 ubuntu
net-1 (first network): Gets the specified MAC address 02:42:ac:11:00:02
net-2 (subsequent networks): Gets auto-generated MAC address
I am not sure about podman but docker simply does not support inputting multiple --network flags in the run command when a single --mac-address is specified. [Edited]
docker run -d --name test-mac-container --mac-address 02:42:ac:11:00:99 --network test-net-1 --network test-net-2 --network test-net-3 alpine sleep 300
docker: Error response from daemon: Container cannot be connected to network endpoints: test-net-1, test-net-2, test-net-3.
See 'docker run --help'.
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That's interesting, according to Docker docs multiple networks should be supported. Could it be related to the --mac-address flag even though the error message is a bit vague? (or maybe that's what you meant)
I don't have Docker installed at the moment, but I tried how Podman works in a VM:
# by default podman uses host networking
# podman also has a default bridge network that can be used with either --network=bridge or --network=podman, same as --network=default or no --network in apple/container
# create two custom named bridge networks:
$ podman network create net-1 # gets the network 10.89.0.0/24
$ podman network create net-2 # gets the network 10.89.1.0/24
$ podman run --rm -it --network=bridge --mac-address=02:00:00:00:00:01 alpine # default bridge network gets static mac (command fails with just --mac-address but that's due to the network type)
$ podman run --rm -it --network=net-1 --mac-address=02:00:00:00:00:01 alpine # custom bridge network net-1 gets static mac
$ podman run --rm -it --network=net-1 --network=net-2 alpine # starts (random mac for both)
$ podman run --rm -it --mac-address=02:00:00:00:00:01 --network=net-1 --network=net-2 alpine # fails
Error: --mac-address can only be set for a single network: invalid argument
$ podman run --rm -it --network=net-1:mac=02:00:00:00:00:01 --network=net-2 alpine # net-1 gets static mac, net-2 gets random mac
$ podman run --rm -it --network=net-1:mac=02:00:00:00:00:01 --network=net-2:mac=02:00:00:00:00:02 alpine # both get static macThere was a problem hiding this comment.
You're right, I apologize. I should've clarified that the docker example failing was in the case when the --mac-address flag is specified with multiple networks.
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Type of Change
Motivation and Context
[Why is this change needed?]
Currently, there is no way to specify a custom MAC address for a container's network interface and the MAC address is auto-generated by the system.
Use Cases
Testing
Issue
closes #752