A number of Kubernetes commands can be used to debug issues related to the node boot process. All of the traffic bound for the DHCP server, TFTP server, and Boot Script Service (BSS) is sent on the Node Management Network (NMN).
In the current arrangement, all three services are located on a management non-compute node (NCN).
Thus, traffic must first travel through the NCN to reach these services inside their pods. When attempting to track down missing requests for either DHCP or TFTP,
it is helpful to set up tcpdump on the NCN where the pod is resident to ensure that the request got that far.
The NODE column in the output of kubectl get pods -o wide shows which node the pod is running on.
Check if a Kubernetes pod is running.
ncn-mw# kubectl get pods -A -o wide | grep pod_name
Example command:
ncn-mw# kubectl get pods -n services -o wide|grep -E "NAME|kea"
Example output:
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
cray-dhcp-kea-6b78789fc4-lzmff 3/3 Running 0 5d12h 10.42.0.30 ncn-w002 <none> <none>
Retrieve logs for a specific Kubernetes pod.
ncn-mw# kubectl logs -n NAMESPACE pod_name
Example command:
ncn-mw# kubectl get pods -n services -o wide|grep -E "NAME|kea"
Example output:
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
cray-dhcp-kea-6b78789fc4-lzmff 3/3 Running 0 5d12h 10.42.0.30 ncn-w002 <none> <none>
Example command:
ncn-mw# kubectl logs -n services DHCP_KEA_POD_ID -c CONTAINER
Beginning of example output:
DHCPDISCOVER from a4:bf:01:23:1a:f4 via vlan100
ICMP Echo reply while lease 10.100.160.199 valid.
Abandoning IP address 10.100.160.199: pinged before offer
Reclaiming abandoned lease 10.100.160.195.
Gain access to a Kubernetes pod.
Use the following command to enter a shell inside a container within the pod. Once inside the shell, execute commands as needed.
ncn-mw# kubectl exec -A -it pod_name /bin/sh
Example command for a pod named cray-dhcp-kea-6b78789fc4-lzmff:
ncn-mw# kubectl exec -A -it cray-dhcp-kea-6b78789fc4-lzmff /bin/sh