This controller watches for changes to ConfigMap objects and performs rolling upgrades on their associated deployments for apps which are not capable of watching the ConfigMap and updating dynamically.

This is particularly useful if the ConfigMap is used to define environment variables - or your app cannot easily and reliably watch the ConfigMap and update itself on the fly.

For a Deployment called foo have a ConfigMap called foo. Then add this annotation to your Deployment

metadata:
  annotations:
    configmap.fabric8.io/update-on-change: "foo"

Then, providing configmapcontroller is running, whenever you edit the ConfigMap called foo the configmapcontroller will update the Deployment by adding the environment variable:

FABRICB_FOO_REVISION=${configMapRevision}

This then triggers a rolling upgrade of your deployment's pods to use the new configuration.