Communication Between Different Services in Kubernetes Deploy
I'm new to using Kubernetes (v 1.11.2-gke.18), and am trying to get Sentry running as a Kubernetes deployment. This is all being run in Google Cloud. Here's the YAML files for Postgres, Redis, and Sentry:
The Redis and Postgres parts seem to be up and running just fine, but Sentry fails because: could not translate host name "postgres-sentry:5432" to address: Name or service not known.
My question is this: How do I get these services to communicate properly? How do I get the Sentry container to communicate with Postgres and Redis?
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2 Answers
It turns out that in this case, what I needed was to change the SENTRY_REDIS_HOST and SENTRY_POSTGRES_HOST values to not have the port numbers in the env declaration. Taking those out made everything talk together as expected.
In Kubernetes pods generally can find other pods through services using DNS.
Your configuration looks correct if postgres-sentry is in the same namespace as your sentry app pod/deployment (which looks like the default namespace).
So it points that you may have a problem with DNS. You can check by shelling into the sentry app container/pod and trying to ping postgres-sentry:
$ kubectl exec -it <pod-id-of-your-sentry-app> sh
# ping postgres-sentryAlso, check if you have you /etc/resolv.conf looks something like this:
# cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local
options ndots:5Finally, check if your DNS pods are running:
$ kubectl -n kube-system get pods | grep dns
coredns-xxxxxxxxxxx-xxxxx 1/1 Running 15 116d
coredns-xxxxxxxxxxx-xxxxx 1/1 Running 15 116d