A ConfigMap volume exposes each entry in a Kubernetes ConfigMap as a file inside a container. It is especially useful for large or multiline configuration that is awkward to pass through environment variables. The same volume can be combined with environment-variable references when an application needs both forms. section 9.5.1 section 8.2.1
Mounting configuration files
Define a volume that references the ConfigMap, then mount it into the container. For example, a volume named envoy-config can reference kiada-ssl-config and expose its files under /etc/envoy. A process can then read files such as envoy.yaml or status-message. Use the items field when only selected ConfigMap entries should appear.
Account for these operational behaviors:
- A missing, non-optional ConfigMap prevents the pod's volumes from being set up, so all containers remain unable to start. section 9.5.1
- Mounting a volume over a directory hides files supplied by the container image, including subdirectories. Mount a single file with subPath when existing directory contents must remain visible. section 9.5.2
- Kubernetes uses symbolic links so ConfigMap files can be updated atomically; inspect the mounted directory to see the versioned directory, ..data, and file links. section 9.5.2
