varnish/hitch

Shared-cache update peer-list in k8s

edgsantos opened this issue · 3 comments

edgsantos commented

Going through the hitch repo I noticed that hitch has support for shared-cache
Problem being, from my understanding if i have a 3 POD setup, each hitch container must know the IP of the remaining PODs to fill the shared-cache-peer list.

Any guidance on how this could be done in kubernetes?
In a VM setup it would be relatively easy to change the configuration upon a change using Puppet or Chef. Using a more dynamic setup like kubernetes i'm struggling to find a proper way to keep the peer list updated?

Thanks

gquintard commented

Hi,

There are a couple of facets to that (interesting) question:

  • we don't currently enable this in our packages, so you would have to build your own
  • at the moment, we don't reload the IP lists, so that is moderately useful if you want to clamp down the peers to the exactly the k8s population
  • you could use an operator or something like discovery (not open-source though) to list an reload, once it's supported
  • that being said, given that there appears to be multicast support (I haven't tested it), does it matter that you can't precisely list all the pods?
edgsantos commented

that being said, given that there appears to be multicast support (I haven't tested it), does it matter that you can't precisely list all the pods?

Multicast works and seems a way better alternative than keeping lists of IPs 👍
@gquintard are you able to point me to some documentation / code that talks about multicast support?

gquintard commented

I really only looked #115 (comment) which seems straightforward, but there may be dragons

  • 👍1