# Part 3: Using Deployments

This is Part 3 of a multi-part, self-paced quick start exercise.

**Note**  
This exercise requires MicroK8s. If you do not have these already installed and running, see " [Prerequisites](https://docs.rafay.co/learn/quickstart/kubernetes/prerequisites/)".

---

## What Will You Do  
In part 3, you will:

- Use Deployments to update your pods.

**Estimated Time**  
Estimated time for this exercise is 10 minutes. Watch a video of the exercise below.

[Kubernetes 101 -Deployments](https://www.youtube.com/watch?v=sHDdHfuC2FI)

---

## Using Deployments  
A Deployment provides declarative updates for Pods and ReplicaSets. This exercise will focus on Deployments.

### Deployment YAML file  
Create a deployment using a YAML file, which is a configuration file. You could create a YAML file from the command line, but for this exercise, you can just use a text editor. Or you can download the deployment YAML file from from this public [Git repository](https://github.com/RafaySystems/getstarted/tree/master/kubernetes).

1. Open the Terminal.
2. Navigate to the Downloads folder.

```
   cd ./Downloads
   ```

3. Use the following command to create an empty YAML file in your Downloads folder.

```
   touch deployment.yaml
   ```

4. Use the nano text editor in the Terminal.

```
   nano deployment.yaml
   ```

5. Copy and paste the configuration below into the text editor.
6. Press **Cmd + X**, then type **Y** and press **Return** to save the deployment.yaml file.

---

### Add a Deployment  
1. In the Terminal or Command Prompt, list the resources in the current namespace. There may not be any resources listed.

```
   microk8s kubectl get deployment -o wide
   ```

2. Use the deployment.yaml file to manage your pods.

```
   microk8s kubectl create -f deployment.yaml
   ```

3. List resources in the current namespace. You now have a test-deployment using the python-http-server container.

```
   microk8s kubectl get deployment -o wide
   ```

4. View a list of replicasets.

```
   microk8s kubectl get replicaset
   ```

5. View the list of pods. Copy the name of one of the pods. Make sure the test-deployment pods are ready.

```
   microk8s kubectl get pods
   ```

6. Access the pod. Replace **_pod-name_** with the name of the pod.

```
   microk8s kubectl exec -it pod-name -- bash
   ```

7. Run a curl command. You should see the response included in the YAML file, including the name for the pod.

```
   curl http://localhost
   ```

8. Exit the pod.

```
   exit
   ```

---

## deployment.yaml  
```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: test-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: test-pod
  template:
    metadata:
      labels:
        app: test-pod
    spec:
      containers:
      - name: python-http-server
        image: python:2.7
        command: ["/bin/bash"]
        args: ["-c", "echo \" Hello from $(hostname)\" > index.html; python -m SimpleHTTPServer 80"]
        ports:
        - name: http
          containerPort: 80
```