Support dual stack?

[penaivanalejandro]

Hi, i want to know if the container support dual stack?? I mean ipv4 and ipv6 in the same container?

[robinsmidsrod]

Not with the single network interface invocation mode, it does not. In fact, the entrypoint script in the container explicitly sets the -4 parameter to dhcpd. See

docker-dhcpd/util/entrypoint.sh

Line 72 in 760ab67

$run /usr/sbin/dhcpd -4 -f -d --no-pid -cf "$data_dir/dhcpd.conf" -lf "$data_dir/dhcpd.leases" $IFACE

for the exact details.

You can of course run the container with custom arguments, but then you lose out on some of the benefits that the entrypoint script gives you.

I seem to recall that there are some issues surrounding running both IPv4 and IPv6 from the same configuration, but I don't have my notes in front of me now, so I'm not sure.

In terms of extending the entrypoint script to support IPv4, IPv6 or both then we could introduce e.g. an environment variable that defines which mode you want, and potentially a variable that lets to specify additional command-line arguments to pass to dhcpd. If you're able to create a pull request that adds these features, but maintains backwards compatibility, then I'd be inclined to accept it.

[robinsmidsrod]

Solved via #27 with DHCPD_PROTOCOL=6 environment variable on the docker run command.

[liyihuang]

I dont think this is the correct way to support the dual stack. I can only choose to run either in ipv4 and ipv6. I think we need to run 2 different processes and config file to support the dual stack

[robinsmidsrod]

@liyihuang That (one process = one protocol) is the intent of the above. What do you propose as an alternative? This container is built on the concept of the single-responsibility-principle (Unix philosophy). Do one thing, and do it well.

[liyihuang]

I just realized that I can just spin up another one for the ipv6 so it should be fine...