By guy1234
I have three nodes in the cluster. Prometheus pods (which include server, alertmanager, node_exporter etc) start just fine. Unfortunately 2 of the 3 node_exporters cannot be reached. This seems like it must be some issue with flannel, but I don’t know how to begin to debug this.
Prometheus itself (the dashboard) reports the error “context deadline exceeded” for the 2 node_exporter pods. When I create a single “curl” pod for curling ClusterIPs, the curl command hangs when trying to connect to these two.
So the question is how does one verify that flannel is functioning correctly?
Reproduce:
helm install --name prometheus-service stable/prometheus kubectl port-forward prometheus-service-server-<id> 9090 http://localhost:9090/targets (view in browser)
And see that some (perhaps all but one) of the node_exporter pods report “context deadline exceeded”.
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FYI i was able to fix this issue by adding the port 9100 in the k8s firewall and addresses: 10.0.0.0/8 172.16.0.0/20 192.168.0.0/16
I am wondering if there is something incorrect about how my nodes are set up or I just don’t understand how the networking is supposed to work.
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Get a listing of the nodes: kubectl get nodes -o wide
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Create a pod that can curl: kubectl run curl --image=radial/busyboxplus:curl -i --tty
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Try curling the internal-ip that is listed from #1. curl INTERNAL-IP
The result is that the curl pod can only curl the node that it is apart of. Is this how this is supposed to work? Curling any other node’s internal-ip results in curl hanging.
Make sure to open tcp/9100 from 10.0.0.0/8 172.16.0.0/20 192.168.0.0/16 in the DO firewall panel of your cluster.
You might also have noticed that prometheus fails to get kubelet metrics. Watch this question for updates: https://www.digitalocean.com/community/questions/cannot-install-heapster-to-cluster-due-to-kubelets-not-allowing-to-get-metrics-on-port-10255
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