When doing containerization, often there is a need to have some configurations manageable from outside the container. After a container has booted with certain pre-configured data, it is necessary to have a way by which this data can be modified at runtime, if needed. For instance, we may have different configurations for different deployment environments and we may want to use the correct set of configurations for a target environment without re-creating the container.
Kubernetes provides ConfigMap to help configure data externally. This follows the design paradigm - "separation of config from code." The ConfigMap API makes the application portable. The configuration can be changed without redeploying the application.