Kubernetes exposes commands to help you debug from the node level without getting into the worker node using SSH. To accomplish this, run the oc debug/kubectl debug command to gain access to host filesystem and networking.
Topic | Command/location |
---|
Interface Operations | - Run
tcpdump/tshark on the host interfaces to capture packets - Obtain the link status of the host interface.
- Run ethtool on the parent interface to see the enabled/disabled flags
|
Container, Kubernetes and Kernel Logs | - The worker node logs, pertaining to the containers scheduled on the node, are available at:
/host/var/log/containers/ - The Kernel logs and Kubernetes logs (like pod creation/deletion, container creation/deletion, probes logs) are available at:
/host/var/log/journal/
Note: For decoding the journal logs, use the journalctl command. |
Host Configuration | Browse through the host configuration if you suspect the host configuration. |
Debug Pod | The following command should work in most cases to create the debug pod. oc debug node/mynode -it --image=ubuntu
But in instances where the CPU policy manager is enabled, the command throws an error. In this case, you must use the template to create debug containers/pods on specific nodes. |
apiVersion: v1
kind: Pod
metadata:
annotations:
debug.openshift.io/source-container: container-00
debug.openshift.io/source-resource: /v1, Resource=nodes/worker-11.blr-ocp1.lab.rbbn.com
creationTimestamp: null
name: worker-11-debug-container
namespace: sbc-svt
spec:
containers:
- command:
- /bin/sh
image: quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:bbd63f50a9dce72a97d6abb350b0fbaa013c76500fe434ce26a197f230146ae3
name: container-00
resources: {}
securityContext:
privileged: true
runAsUser: 0
resources:
limits:
cpu: 100m
memory: "200Mi"
requests:
cpu: 100m
memory: "200Mi"
stdin: true
stdinOnce: true
tty: true
volumeMounts:
- mountPath: /host
name: host
hostNetwork: true
hostPID: true
nodeName: worker-11.blr-ocp1.lab.rbbn.com
restartPolicy: Never
volumes:
- hostPath:
path: /
type: Directory
name: host
Reference links: