K8S Deployment Dev-nuller

devnull

#!/bin/bash
#   Usage: devnuller <deployment>
#     When troubleshooting k8s deployments, it is sometimes helpful to set command: ["tail", "-f", "/dev/null"]
#     so that you have a long-running null-command, allowing you to `kubectl exec ...` in and troubleshoot the
#     environment. This will do that, and tell you how to roll back your command.

DEPLOYMENT="

P_REV=$(kubectl get deployment/${DEPLOYMENT} -o json | \
          jq -r '.metadata.annotations["deployment.kubernetes.io/revision"]')
echo "---> Dev Nuller: Command will be set to `tail -f /dev/null`"
echo "---> Rollback command:"
echo "kubectl rollout undo deployment/${DEPLOYMENT} --to-revision=${P_REV}"

echo -n "Proceed? [N/y]"; read PROCEED

if [[ "${PROCEED}" == "y" ]]; then
    kubectl patch deployment/${DEPLOYMENT} \
        --type="json" \
        -p="[{\"op\": \"replace\", \"path\": \"/spec/template/spec/containers/0/command\", \
        \"value\":[\"tail\", \"-f\", \"/dev/null}\"}]"
else
    exit 1
fi