I first asked this question on Stack Overflow but I woke up this morning to the realization that it belongs over here.
I'm setting up an InnoDB Cluster using mysqlsh. This is in Kubernetes, but I think this question applies more generally.
When I use cluster.configureInstance() I see messages that includes:
This instance reports its own address as node-2:3306
However, the nodes can only find each other through DNS at an address like node-2.cluster:3306. The problem comes when adding instances to the cluster; they try to find the other nodes without the qualified name. Errors are of the form:
[GCS] Error on opening a connection to peer node node-0:33061 when joining a group. My local port is: 33061.
It is using node-n:33061 rather than node-n.cluster:33061.
If it matters, the "DNS" is set up as a headless service in Kubernetes that provides consistent addresses as pods come and go.It's very simple, and I named it "cluster" to created addresses of the form node-n.cluster. The cluster itself is a statefulset that numbers nodes sequentially. I don't want to cloud this question with detail I don't think matters, however, as surely other configurations require the instances in the cluster to use DNS as well.
I thought that setting localAddress when creating the cluster and adding the nodes would solve the problem. Indeed, after I added that to the createCluster options, I can look in the database and see
| group_replication_local_address | node-0.cluster:33061 |
Yet when I look at the topology, it seems that the localAddress option has no effect whatsoever (at this point I don't see what it does at all):
{
"clusterName": "mycluster",
"defaultReplicaSet": {
"name": "default",
"primary": "node-0:3306",
"ssl": "REQUIRED",
"status": "OK_NO_TOLERANCE",
"statusText": "Cluster is NOT tolerant to any failures.",
"topology": {
"node-0:3306": {
"address": "node-0:3306",
"memberRole": "PRIMARY",
"mode": "R/W",
"readReplicas": {},
"replicationLag": null,
"role": "HA",
"status": "ONLINE",
"version": "8.0.29"
}
},
"topologyMode": "Single-Primary"
},
"groupInformationSourceMember": "node-0:3306"
}
And adding more instances continues to fail with the same communication errors.
Notable perhaps that I cannot set localAddress to node-0.cluster:3306; I get a message that that port is already in use. I tried 3307 but as before it had no effect.
How do I convince each instance that the address it needs to advertise is different? I will try other permutations of the localAddress setting, but it doesn't look like it's intended to fix the problem I'm having. How do I reconcile the address the instance reports for itself with the address that's actually useful for other instances to find it?
Edit to add: Maybe it is a Kubernetes thing? Kubernetes sets the hostname of the pod to match the name of the pod. If so, how do I override it?
There has to be a way to tell the cluster to use something other than the machines' hostnames for discovering each other.
