configMap

ConfigMap is a Kubernetes API object that stores non-confidential configuration data as key-value pairs. It provides a way to decouple configuration from container images, enabling changes without rebuilding images. ConfigMaps are namespace-scoped and can be consumed by pods in two main ways: as environment variables or as files mounted into a container.

The data model includes data, which is a map of string keys to string values, and binaryData, which holds arbitrary binary data encoded as base64. Each ConfigMap has standard metadata such as name, namespace, labels, and annotations. The total size of a ConfigMap is limited (roughly 1 MiB, depending on the cluster).

ConfigMaps can be created from literals, from files, or from directories. For example, you can create a ConfigMap named app-config from literal keys or from a directory whose file names become keys. YAML manifests may define apiVersion: v1, kind: ConfigMap, with either data or binaryData fields.

To use a ConfigMap in a pod, you can reference it in the pod spec. With environment variables, you can populate all keys via envFrom: configMapRef or individual keys via valueFrom: configMapKeyRef. With volumes, you mount the ConfigMap at a path and each key becomes a file containing the corresponding value. You can use items to rename keys or to limit which keys are exposed.

Updates: When a ConfigMap is updated, files mounted as a volume are updated by the kubelet, while environment variables do not automatically update and may require pod restart to reflect changes.