rkt: support socket activated units

[philips]

This should be a straight forward conversion from the ports list to loading in socket units.

[pierreozoux]

👍

[iaguis]

IIUC this is fixed by #214, right?

[alban]

It would be nice to have a test for this :)

[alban]

I would like systemd on the host to listen on a socket for socket activating the container. Then, when an incoming connection triggers the rkt pod to start, the file descriptor would be passed:

• from systemd on the host to rkt
• from rkt to stage1's init
• from init to systemd-nspawn
• from systemd-nspawn to systemd in the container
• from systemd in the container to the app

I am not sure #214 does everything and it would be nice to have a test for the complete sequence.

[kneufeld]

@alban I know this is an ancient bug but I'm trying to get this working. I feel like I'm super close but alas I cannot get it to work.

My question is, can you run your socket accepting daemon directly or do you have to do the systemd-inside-the-container-to-the-app dance?

The docs I've found on this are non-existant or very vague. When trying to pass in a socket what goes in the '--port' parameter of the rkt command line?

Thanks.

[iaguis]

Hi!

There's an example in https://github.com/coreos/rkt/blob/master/Documentation/using-rkt-with-systemd.md#socket-activated-service. Have you tried following that?

If after that you still have problems please let us know!

[kneufeld]

Thanks @iaguis but I did look at that document. I forgot to mention that what I'd like is a container per connection. In other words I want a service named foo@.service.

I did notice the following line on this re-read:

An application needs to be able to accept sockets from systemd's native socket passing interface in order to handle socket activation.

Can rkt not support passing in a socket and attaching it to the apps stdin/stdout? That's how the app currently works and I believe how all inetd started apps work.

[iaguis]

Can rkt not support passing in a socket and attaching it to the apps stdin/stdout? That's how the app currently works and I believe how all inetd started apps work.

This is not supported at the moment :(

[kneufeld]

Well that would explain why I've been unsuccessfully banging my head against the wall. :( indeed.

Thanks for the tech support!

[iaguis]

Np. Would you mind filing an issue about it?