csrfr
Distributed Services with Go: accessing the service outside the pods (Beta-4 pg.223)
Once deployed, I am not able to access the service outside the prolog pods. I can run the client successfully and access the service from a client running on one of the proglog pods.
However, I am not able to access the service from the following locations:
-
Laptop: The client connection hangs and then returns
connection error while dialing dial tcp: lookup proglog-0.proglog.mysvcs.svc.cluster.local: no such host.I am dialing using the EXTERNAL-IP address of proglog-0 from k8s in the client (This address works when used from a proglog pod). -
From a pod in the k8s cluster but not a proglog pod. It prints the following error repeatedly
ERROR: 2020/10/31 18:59:29 [core] subconn returned from pick is not *acBalancerWrapper. Also, the acBalancerWrapper error appears when running the client from a proglog pod (where it usually works) from time to time.
Anyone faced this before, ideas?
At the moment I’m looking into GetServers returning the K8s DNS names (e.g. proglog-0.proglog.default.svc.cluster.local:8400 rather than the EXTERNAL-IP of the pods.
Marked As Solved
travisjeffery
Yeah we should return ErrNoSubConnAvailable like so:
func (p *Picker) Pick(info balancer.PickInfo) (
balancer.PickResult, error) {
p.mu.RLock()
defer p.mu.RUnlock()
var result balancer.PickResult
if strings.Contains(info.FullMethodName, "Produce") ||
len(p.followers) == 0 {
result.SubConn = p.leader
} else if strings.Contains(info.FullMethodName, "Consume") {
result.SubConn = p.nextFollower()
}
if result.SubConn == nil {
return result, balancer.ErrNoSubConnAvailable
}
return result, nil
}
so gRPC will block the RPC until a new picker is available with available sub connections.
Also Liked
travisjeffery
For 1. did you port-forward the pod/service to expose it outside k8s’ network? That’s what the $ kubectl port-forward pod/proglog-0 8400 8400 command in the book is for.
- Could be because leader election is still underway so a nil subconn is returned for it.
travisjeffery
For 2. I think the error handling should be improved. I’m looking into it.
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