Posibility to have backend drain via dataplane API

[wizardmatas]

Hello, HaProxy has backend server drain functionality, it would be great to have drain funkcionality via REST API. Is it possible to include it or get some guidance how to contribute to add it.

Thanks

[mjuraga]

We are planning to add an endpoint that would handle Runtime API (aka stats socket) commands, but for this purpose you can set the server weight to 0 through the Data Plane API and have the same effect: "A value of 0 means the server will not participate in load-balancing but will still accept persistent connections."

Note that changing the server weight will be done through the Runtime API and it will not reload haproxy process.

[wizardmatas]

Hi, that is great. Do you have any ETA for Runtime API support ?
Thanks,
Matas

[mjuraga]

Runtime API support is being worked on but we are not yet ready to announce an ETA for it. We are also collecting community feedback which might influence our roadmap.

[apsega]

@mjuraga any updates on this?

[aiharos]

@mjuraga any updates on this?

@apsega we're not yet ready to announce anything at this time. Perhaps you can tell us what aspect of the Runtime API you are interested in, to inform us better? If it's not related to draining backends, you can also open a new issue.

Thanks!

[mjuraga]

Hi @apsega @wizardmatas, I have just pushed a79a419. This adds runtime_servers endpoints which allow you to change some runtime (transient) server properties. On GET we use this: https://cbonte.github.io/haproxy-dconv/2.0/management.html#show%20servers%20state

And then you can change the server admin (set server state) and operational (set server health) states. Here you can change each servers admin state to drain. So you can iterate through servers in the backend and set them to drain.