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kuberneteskubernetes-pod

Kubernetes liveness probe: can a pod monitor its own stdout?

My idea was to implement a liveness probe as a command, and use something like

$ grep something ERROR

from inside a pod, so that if in the output of a pod, a line containing ERROR exists, the liveness probe fails.

Is this possible? If not, is it possible if I add another container in the same pod, to monitor the first container?

Solution

  • You could query the Kubernetes API server.

    The request looks like this:

    GET /api/v1/namespaces/{namespace}/pods/{name}/log

    To use the token that's usually mounted in a Pod, you can call it like this:

    curl https://kubernetes/api/v1/namespaces/default/pods/$HOSTNAME/log -k \
     -H "Authorization: Bearer $(cat /var/run/secrets/kubernetes.io/serviceaccount/token)"