Upgrade Cilium 1.20 with preflight checks and connectivity tests
A Cilium upgrade changes the software that programs the Kubernetes networking and security datapath on every node. That is a larger operational boundary than a routine Deployment rollout. Agents, operators, CNI configuration, eBPF programs, service load balancing, and policy enforcement need to agree on a release while workloads continue to resolve DNS and establish connections.
This guide prepares a Helm-managed Kubernetes cluster for Cilium 1.20.0, runs the documented preflight workload, upgrades with a reviewed values file, and verifies the finished state with the Cilium CLI. A successful result is that the Cilium DaemonSet and operator report healthy, the installed images are 1.20.0, and cilium connectivity test completes without failures. The commands are documentation-verified against Cilium 1.20 documentation, not tested against a live cluster. Run them only against a cluster you administer and adapt the namespace, chart registry, API-server settings, and maintenance window to the installation.