In order to create Deployment objects, as usual, use the kubectl run command or prepare the YAML/JSON file that describe Deployment configuration. This example is using the kubectl run command to create a my-nginx Deployment object:

//create my-nginx Deployment (specify 3 replicas and nginx version 1.11.0)
$ kubectl run my-nginx --image=nginx:1.11.0 --port=80 --replicas=3
deployment.apps "my-nginx" created


//see status of my-nginx Deployment
$ kubectl get deploy
NAME       DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
my-nginx   3         3         3            3           8s


//see status of ReplicaSet
$ kubectl get rs
NAME                 DESIRED   CURRENT   READY     AGE
my-nginx-5d69b5ff7   3         3         3         11s


//see status of Pod
$ kubectl get pods
NAME                       READY     STATUS    RESTARTS   AGE
my-nginx-5d69b5ff7-9mhbc   1/1       Running   0          14s
my-nginx-5d69b5ff7-mt6z7   1/1       Running   0          14s
my-nginx-5d69b5ff7-rdl2k   1/1       Running   0          14s

As you can see, a Deployment object my-nginx creates one ReplicaSet, which has an identifier: <Deployment name>-<hex decimal hash>. And then ReplicaSet creates three Pods which have an identifier: <ReplicaSet id>-<random id>.

This diagram illustrates the Deployment, ReplicaSet, and Pod relationship:

Because of this relationship, if you perform delete on a my-nginx Deployment object, it will also attempt to delete ReplicaSet and Pods respectively:

//delete my-nginx Deployment
$ kubectl delete deploy my-nginx
deployment.extensions "my-nginx" deleted


//see status of ReplicaSet
$ kubectl get rs
No resources found.
 

//see status of Pod, it has been terminated
$ kubectl get pods
NAME                       READY     STATUS        RESTARTS   AGE
my-nginx-5d69b5ff7-9mhbc   0/1       Terminating   0          2m
my-nginx-5d69b5ff7-mt6z7   0/1       Terminating   0          2m
my-nginx-5d69b5ff7-rdl2k   0/1       Terminating   0          2m

This example is just a simple create and delete, that easy to understand Deployment object and ReplicaSet object 1:1 relationship at this moment. However, a Deployment object can manage many ReplicaSets to preserve as a history. So the actual relationship is 1:N, as in the following diagram:

To understand the 1:N relationship, let's recreate this Deployment object again and perform to make some changes to see how Deployment manages ReplicaSet history.