Rolling Updates and Rollbacks

1

Inspect the deployment and identify the number of PODs deployed by it

$ k describe deploy frontend | grep -i desire

2

What container image is used to deploy the applications?

$ k describe deploy frontend | grep -i image

3

Inspect the deployment and identify the current strategy

$ k describe deploy frontend | grep -i strategy

4

Let us try that. Upgrade the application by setting the image on the deployment to kodekloud/webapp-color:v2

Do not delete and re-create the deployment. Only set the new image name for the existing deployment.

$ k edit deploy frontend

image: kodekloud/webapp-color:v2

5

Run the script curl-test.sh. Notice the requests now hit both the old and newer versions. However none of them fail.

Execute the script at /root/curl-test.sh.

$ sh curl-test.sh

6

Change the deployment strategy to Recreate

Delete and re-create the deployment if necessary. Only update the strategy type for the existing deployment.

$ k edit deploy frontend

strategy:
  type: Recreate

7

Upgrade the application by setting the image on the deployment to kodekloud/webapp-color:v3

Do not delete and re-create the deployment. Only set the new image name for the existing deployment.

$ k edit deploy frontend

image: kodekloud/webapp-color:v3

Commands and Arguments

1

How many PODs exist on the system?

In the current(default) namespace

$ k get pods

2

What is the command used to run the pod ubuntu-sleeper?

$ k describe pod ubuntu-sleeper | grep -iA 3 command

3

Create a pod with the ubuntu image to run a container to sleep for 5000 seconds. Modify the file ubuntu-sleeper-2.yaml.

Note: Only make the necessary changes. Do not modify the name.

ubuntu-sleeper-2.yaml

apiVersion: v1
kind: Pod 
metadata:
  name: ubuntu-sleeper-2
spec:
  containers:
  - name: ubuntu
    image: ubuntu
    command: ["sleep","5000"]
    
$ k apply -f ubuntu-sleeper-2.yaml

4

Create a pod using the file named ubuntu-sleeper-3.yaml. There is something wrong with it. Try to fix it!


Note: Only make the necessary changes. Do not modify the name.

ubuntu-sleeper-3.yaml

apiVersion: v1
kind: Pod 
metadata:
  name: ubuntu-sleeper-3
spec:
  containers:
  - name: ubuntu
    image: ubuntu
    command:
      - "sleep"
      - "1200"
      
$ k apply -f ubuntu-sleeper-3.yaml

5

Update pod ubuntu-sleeper-3 to sleep for 2000 seconds.

$ k edit pod ubuntu-sleeper-3
containers:
  - command:
    - sleep
    - "2000"
$ k delete pod ubuntu-sleeper-3
$ k apply -f /tmp/kubectl-edit-3512171132.yaml

6

Inspect the file Dockerfile given at /root/webapp-color directory. What command is run at container startup?

$ cd webapp-color
$ cat Dockerfile
ENTRYPOINT ["python", "app.py"]

7

Inspect the file Dockerfile2 given at /root/webapp-color directory. What command is run at container startup?

$ cat Dockerfile2
ENTRYPOINT ["python", "app.py"]
CMD ["--color", "red"]

8

Inspect the two files under directory webapp-color-2. What command is run at container startup?

Assume the image was created from the Dockerfile in this directory.

$ cd ~/webapp-color-2
$ cat cat webapp-color-pod.yaml
command: ["--color","green"]

9

Inspect the two files under directory webapp-color-3. What command is run at container startup?

Assume the image was created from the Dockerfile in this directory.

$ cd ~/webapp-color-3
$ cat cat webapp-color-pod-2.yaml
command: ["python", "app.py"]
args: ["--color", "pink"]

10

Create a pod with the given specifications. By default it displays a blue background. Set the given command line arguments to change it to green.

$ cd ~/webapp-color-2
$ vi webapp-color-pod.yaml

apiVersion: v1 
kind: Pod 
metadata:
  name: webapp-green
  labels:
      name: webapp-green 
spec:
  containers:
  - name: simple-webapp
    image: kodekloud/webapp-color
    args: ["--color", "green"]
    
$ k apply -f webapp-color-pod.yaml

Env Variables

1

How many PODs exist on the system?

in the current(default) namespace

$ k get pods

2

What is the environment variable name set on the container in the pod?

$ k describe pod webapp-color | grep -iA 5 env

3

What is the value set on the environment variable APP_COLOR on the container in the pod?

$ k describe pod webapp-color | grep -iA 5 env

4

Update the environment variable on the POD to display a green background.

Note: Delete and recreate the POD. Only make the necessary changes. Do not modify the name of the Pod.

$ k edit pod webapp-color
spec:
  containers:
  - env:
    - name: APP_COLOR
      value: green
      
$ k delete pod webapp-color
$ k apply -f /tmp/kubectl-edit-4270112926.yaml

5

How many ConfigMaps exists in the default namespace?

$ k get cm

6

Identify the database host from the config map db-config.

$ k describe cm db-config

7

Create a new ConfigMap for the webapp-color POD. Use the spec given below.

$ k create cm webapp-config-map --from-literal=APP_COLOR=darkblue --from-literal=APP_OTHER=disregard

8

Update the environment variable on the POD to use only the APP_COLOR key from the newly created ConfigMap.

Note: Delete and recreate the POD. Only make the necessary changes. Do not modify the name of the Pod.

$ k edit pod webapp-color
spec:
  containers:
  - env:
    - name: APP_COLOR
      valueFrom:
        configMapKeyRef:
          key: APP_COLOR
          name: webapp-config-map
          
$ k delete pod webapp-color
$ k apply -f /tmp/kubectl-edit-2833310666.yaml

Secret

1

How many Secrets exist on the system?

In the current(default) namespace.

$ k get secret

2

How many secrets are defined in the dashboard-token secret?

$ k describe secret dashboard-token

3

What is the type of the dashboard-token secret?

$ k describe secret dashboard-token | grep -i type

4

The reason the application is failed is because we have not created the secrets yet. Create a new secret named db-secret with the data given below.

You may follow any one of the methods discussed in lecture to create the secret.

$ k create secret generic db-secret --from-literal=DB_Host=sql01 --from-literal=DB_User=root --from-literal=DB_Password=password123

5

Configure webapp-pod to load environment variables from the newly created secret.

Delete and recreate the pod if required.

$ k edit pod webapp-pod

envFrom:
    - secretRef:
        name: db-secret

Multi Container PODs

1

Identify the number of containers created in the red pod.

$ k get pod red

2

Identify the name of the containers running in the blue pod.

$ k describe pod blue | grep -i container

3

Create a multi-container pod with 2 containers.

Use the spec given below:

If the pod goes into the crashloopbackoff then add the command sleep 1000 in the lemon container.

Name: yellow
Container 1 Name: lemon
Container 1 Image: busybox
Container 2 Name: gold
Container 2 Image: redis

yellow.yaml

apiVersion: v1
kind: Pod
metadata:
  name: yellow
spec:
  containers:
  - name: lemon
    image: busybox
    command:
      - sleep
      - "1000"

  - name: gold
    image: redis
    
$ k apply -f yellow.yaml

4

Inspect the app pod and identify the number of containers in it.

It is deployed in the elastic-stack namespace.

$ k get pod app -n elastic-stack

5

The application outputs logs to the file /log/app.log. View the logs and try to identify the user having issues with Login.

Inspect the log file inside the pod.

$ k -n elastic-stack exec -it app -- cat /log/app.log

6

Edit the pod to add a sidecar container to send logs to Elastic Search. Mount the log volume to the sidecar container.

Only add a new container. Do not modify anything else. Use the spec provided below.

$ k edit pod -n elastic-stack

apiVersion: v1
kind: Pod
metadata:
  name: app
  namespace: elastic-stack
  labels:
    name: app
spec:
  containers:
  - name: app
    image: kodekloud/event-simulator
    volumeMounts:
    - mountPath: /log
      name: log-volume

  - name: sidecar
    image: kodekloud/filebeat-configured
    volumeMounts:
    - mountPath: /var/log/event-simulator/
      name: log-volume

  volumes:
  - name: log-volume
    hostPath:
      # directory location on host
      path: /var/log/webapp
      # this field is optional
      type: DirectoryOrCreate

Init Containers

1

Identify the pod that has an initContainer configured.

$ k describe pod green | grep -i init
$ k describe pod red | grep -i init
$ k describe pod blue | grep -i init

2

What is the image used by the initContainer on the blue pod?

$ k describe pod blue

3

We just created a new app named purple. How many initContainers does it have?

$ k describe pod purple

4

Update the pod red to use an initContainer that uses the busybox image and sleeps for 20 seconds

Delete and re-create the pod if necessary. But make sure no other configurations change.

$ k edit pod red

initContainers:
- image: busybox
  name: red-initcontainer
  command: ["sleep","20"]

$ k delete pod red
$ k apply -f /tmp/kubectl-edit-410690827.yaml