Kubernetes helm read replica access

[ivi]

Hi,

We are using helm to deploy neo4j on a kubernetes cluster starting with this repo:

GitHub

neo4j-contrib/kubernetes-neo4j

(RETIRED) Kubernetes experiments with Neo4j. See updated Helm Repo - neo4j-contrib/kubernetes-neo4j

And i wonder if the applications/drivers need 'direct' access to read replicas (to distribute reads) or only core servers that then use read replicas to process and return queries to apps ?

because they do not seems to be accessible from apps outside of the namespace, when advertising: "bolt://neo4j-replica-3562563584-sckr8:7687"in the routing table.

Thanks for your help,

[david_allen]

Typically you want apps to be able to talk to read replicas so that bolt+routing can route a read query to a replica if need be. There are special cases where this isn't desirable though. Read-only workloads for example which use a lot of CPU and memory you might want to never hit the core nodes and only go to the read replicas.

There are special considerations for bolt+routing in kubernetes though, make sure to have a look:

Medium – 5 Mar 19

Neo4j Considerations in Orchestration Environments

Considerations for running Neo4j on Kubernetes and other Orchestration managers

Reading time: 7 min read

[ivi]

So, read replicas should advertised a fqdn in the k8s cluster, like: bolt://neo4j-replica-3562563584-sckr8.neo4j-replicas.neo4j.svc.cluster.local:7687, like the cores do, right ? (to be available for apps outside of the neo4j namespace), not just:

call dbms.cluster.overview()

• bolt://neo4j-core-0.neo4j-cores.neo4j.svc.cluster.local:7687
• bolt://neo4j-core-0.neo4j-cores.neo4j.svc.cluster.local:7687
• bolt://neo4j-core-0.neo4j-cores.neo4j.svc.cluster.local:7687
• bolt://neo4j-replica-3562563584-sckr8:7687

[david_allen]

Correct. FQDN will make those DNS entries available to anything running in kubernetes (or should). But of course those FQDNs are not resolveable outside of kubernetes, which is something to keep in mind.