This draft captures a real troubleshooting pattern for 504 Gateway Timeout responses behind Kubernetes ingress by checking the ingress rule, backend service, pod health, and in-cluster connectivity from the ingress controller itself.
This draft turns a real GitLab upgrade note into a cleaner walkthrough focused on the upgrade path, the intermediate required version, and the service checks I used after each step.
This draft is based on a real cluster note where I validated private image pulls in Kubernetes by creating a Docker registry secret, attaching it to a deployment, and testing the workload in a dedicated namespace.