Adapt to Weaviate standalone

[etiennedi]

Required Changes

• [x] Previously the weaviate container was stateless and did not require local persistence. With standalone requiring disk access, weaviate can no longer be a Deployment, but needs to be a StatefulSet
• [x] Remove esvector
• [x] Remove etcd (unless still required by the contextionary?)
• [ ] Possibly update contextionary requirements if necessary. Unknown as of today, since this depends on the outcome of semitechnologies/weaviate#1252

[fefi42]

The change successfully removed esvector and adds a statefulset for the weaviate pods. Etcd is still used by the contextionary and thus still kept around.

@etiennedi

1. So far the pvc for the weaviate statefulSet is ReadWriteOnce. However I assume this must be ReadWriteMany once the chart should be horizontally scaleable. As far as I know gke is not supporting ReadWriteMany out of the box so we probably still need to keep the indirect dependency to the NFS provisioner or a similar thing.
2. There was a mention to change all configuration to environment variables instead of the weaviate config map? Is that actually desired? If so is everything over env variables settable? So far authentication and authorization is set over the config, they might become a bit cumbersome in a env variable.

[etiennedi]

Thanks!

1. ReadWriteOnce is fine. When it becomes horizontally scalable in the future, each node/pod will have its own independent disk and Weaviate will - at a software level - take care of replication, etc. Similar to ES or Cassandra. So there won't be multiple pods trying to ever read or write from the same disk.

2. Good point, I'll check and get back to you.