How to get notification inside an application in kubernetes when configmaps get updated

You might be experience a problem like this:

When a ConfigMap changes, the real path to the config files it contains changed, but this is kinda “hidden” by 2 levels of symlinks: [..]

So it seems you need to follow the chain of symlinks and watch that. Since your application is written in go you could just use spf13/viper since the feature WatchConfig and Kubernetes was added.

Alternatively you can get notified by the Kubernetes API on changes of a ConfigMap. This requires configuring some access rules upfront most probably.

Sounds like the Reloader is the one you are looking for. It will watch the configmap/secret and update the deployment related to it.