4.Application Lifecycle Management - Commands and Arguments

LABS – CERTIFIED KUBERNETES ADMINISTRATOR WITH PRACTICE TESTS

> APPLICATION LIFECYCLE MANAGEMENT > COMMANDS AND ARGUMENTS

Application Lifecycle Management

 

1)  Rolling Updates and Rollbacks

2) Commands and Arguments

3) Env Variables

4) Secrets

5) Multi Container PODs

6) Init Containers

 

1. How many PODs exist on the system?

in the current(default) namespace

controlplane ~ ➜  kubectl get pod
NAME             READY   STATUS    RESTARTS   AGE
ubuntu-sleeper   1/1     Running   0          2m27s

 

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

ask : sleep 4800

controlplane ~ ➜  kubectl get pod ubuntu-sleeper -o yaml > ub.yaml 

controlplane ~ ➜  cat ub.yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: "2022-01-20T08:27:58Z"
  name: ubuntu-sleeper
  namespace: default
  resourceVersion: "752"
  uid: 5ebef2e1-9e57-4ff8-b9c4-88ae0812b4bd
spec:
  containers:
  - command:
    - sleep
    - "4800"
    image: ubuntu
    imagePullPolicy: Always
    name: ubuntu
    ...

03. 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.

• Pod Name: ubuntu-sleeper-2
• Command: sleep 5000

command 추가 가능 >>  ['sleep', '5000'] 이런 방법도 있음.

 

04. 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.

• Pod Name: ubuntu-sleeper-3
• Command: sleep 1200

# as-is
- "sleep"
- 12000

# to-be
- sleep
- "12000"

05.

kubectl apply -f ubuntu-sleeper-3.yaml --force

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

1) python app.py (정답)

2) nginx

3) mysqld

4) Flask run

5) sleep 4800

# Inspect the ENTRYPOINT in the Dockerfile
FROM python:3.6-alpine

RUN pip install flask

COPY . /opt/

EXPOSE 8080

WORKDIR /opt

ENTRYPOINT ["python", "app.py"]
~                                                                                                                                             
~

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

1) python app.py --color blue

2) python app.py --color red (정답)

3) python app.py

FROM python:3.6-alpine

RUN pip install flask

COPY . /opt/

EXPOSE 8080

WORKDIR /opt

ENTRYPOINT ["python", "app.py"]

CMD ["--color", "red"]

08. 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 folder

 

ask : python app.py --color red

# Dockerfile2
FROM python:3.6-alpine

RUN pip install flask

COPY . /opt/

EXPOSE 8080

WORKDIR /opt

ENTRYPOINT ["python", "app.py"]

CMD ["--color", "red"]

 

# 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
    command: ["--color","green"]

09. 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 folder

 

ask : python app.py --color pink

 

# webapp-color-pod-2.yaml
apiVersion: v1
kind: Pod 
metadata:
  name: webapp-green
  labels:
      name: webapp-green
spec:
  containers:
  - name: simple-webapp
    image: kodekloud/webapp-color
    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

• Pod Name: webapp-green
• Image: kodekloud/webapp-color
• Command line arguments: --color=green

---
apiVersion: v1 
kind: Pod 
metadata:
  name: webapp-green
  labels:
      name: webapp-green 
spec:
  containers:
  - name: simple-webapp
    image: kodekloud/webapp-color
    args: ["--color", "green"]