What happens when you run 'kubectl apply -f deployment.yaml'? Describe the sequence of events in a Kubernetes cluster.

When executing the command kubectl apply -f deployment.yaml, the following sequence of actions occurs:

1. kubectl client reads the deployment.yaml file and sends its description to the Kubernetes API server.
2. API server validates the manifest, checks access rights, and stores the Deployment object in etcd — the cluster state storage.
3. Deployment controller detects the new or changed Deployment state and begins working to bring the current state to the desired state.
4. The controller creates or updates a ReplicaSet, which in turn creates or deletes the necessary number of Pods.
5. Scheduler assigns new Pods to suitable cluster nodes, considering resources and constraints.
6. On nodes, kubelet runs containers according to the Pod specifications.
7. Deployment monitors the state of Pods, restarting or scaling them if necessary.

Thus, kubectl apply initiates a declarative update of the cluster state, and Kubernetes controllers ensure this state is achieved automatically.