What Is a ConfigMap?

A ConfigMap allows us to define application-related data. A ConfigMap decouples the application data from the application so that the same application can be ported across different environments. It also provides a way to inject customized data into running services from the same container image.

ConfigMaps can be created through a literal value or from a file or all the files in a directory. Note that the primary data we stored in ConfigMaps is for non-sensitive configuration, for example, config files or environment variables.

Once a ConfigMap is defined, it will be loaded to the application via an environment variable or a set of files. The application can then see the files as local files and can read from them. It is important to note that (from 1.9.6 version onward of Kubernetes), files loaded from ConfigMaps are read-only. ConfigMaps can also hold configuration data for system applications such as operators and controllers.

In the following exercises...