When we set up a kubernetes cluster on DigitalOcean, we ran into a very common issue with service discovery. Essentially, pods within the cluster could not access public URLs to the cluster. This usually resulted in a "timeout", "bad header", or SSL error messages. Checking the logs of our pods, this is what we saw:
dial tcp 188.8.131.52:443: connect: connection timed out","time":"2020-04-30T23:56:01Z"}
We emailed DigitalOcean regarding this issue and they responded:
There is a known issue in the kubernetes project for connections from within the cluster accessing public urls to the cluster. When traffic that originates from a Kubernetes pod goes through the Load Balancer, the kube-proxy service intercepts the traffic and directs it to the service instead of letting it go out to the Load Balancer and back to the node.
The support engineer then asked if our services could be resolved via internal dns, or the service's cluster IP. This didn't work for us, unfortunately, but if your service name was
rails-http in the
makisu namespace, then you could access your service like so:
You can double-check this by running a
dnsutils pod. From the Debugging DNS Resolution article on the kubernetes site:
$ kubectl apply -f <https://k8s.io/examples/admin/dns/dnsutils.yaml> pod/dnsutils created $ kubectl exec -ti dnsutils -- nslookup rails-http.makisu Server: 10.0.0.10 Address 1: 10.0.0.10 Name: rails-http.makisu Address 1: 10.0.0.1
The other way that worked for us was to patch the
LoadBalancer service attached to our
nginx-ingress-controller. Following this workaround given to us by the support engineer, we executed this by:
- Adding an
Arecord that points to the
LoadBalancer, name it whatever you want.
- Adding this annotation to the
LoadBalancerservice once the domain name points to the external IP address of the
metadata: annotations: service.beta.kubernetes.io/do-loadbalancer-hostname:L "anything.makisu.co"
When you apply this annotation, your in-cluster services should be able to access other in-cluster services through their public URLs exposed via your ingress.