Commands for docker lab

We are using a simple spring boot application for this demo, whose code is commited in this git repo for reference.

For Docker playground use https://labs.play-with-docker.com (avoid katakoda docker playground for build due to memory and speed issues)

To check the docker version installed

docker -version

To list the running containers

docker ps

To pull the git project and build the docker image

Check the DockerFile used to build the image, in this project root location

git clone https://github.com/aditya4196/Containerization_Demo.git
cd kube-docker-demo
docker build --tag docker-service:2.0 .

To push built docker image to docker hub - please replace dockerhub_userid with your userid e.g adi4196

docker login -u=dockerhub_userid # your login to https://hub.docker.com/
docker tag docker-service:2.0 dockerhub_userid/docker-service:2.0
docker push dockerhub_userid/docker-service:2.0

To pull the image from the docker hub

docker pull docker_userid/docker-service:2.0

To list down the locally stored images

docker images

To delete image from local registery

docker rmi image_id

To create a container from the image pulled

docker run -dp 8080:8080 docker_userid/docker-service:2.0

open a new instance in the docker playground (option available in the left section) and hit curl command 'curl get localhost:8080/employees'

To check running and exited containers

docker ps -a

To check the logs of the container

docker logs container_id

To stop a running container

docker stop container_id

To kill a running container

docker kill container_id

Commands for openshift lab

For Openshift workshop we will use https://www.openshift.com/learn/courses/playground which has pre-configured Openshift Cluster
Tested image to use here adi4196/docker-service:2.0 or your own image which you may have just built
https://www.katacoda.com/openshift/courses/playgrounds/openshift37

Steps to Login and create Namespace in Openshift:

oc login -u developer -p developer
oc new-project docker-app #you can skip this and ues the default myproject as given in katakoda instructions

Pro Tip- use the maximise button to get a better experience of the console in openshift playground/katakoda

In the git root location, you would also find an Openshift-Lab.pdf which has the steps using the Openshift UI platform

To pull and run image in Openshift

oc new-app adi4196/docker-service:1.0

Check the status of the deployment you started

oc status

To check the events of the running deployment

oc get events

LAST SEEN   TYPE     REASON              OBJECT                                   MESSAGE
2m10s       Normal   Scheduled           pod/docker-service-1-deploy              Successfully assigned docker-app/docker-service-1-deploy to crc-rk2fc-master-0
2m1s        Normal   Pulling             pod/docker-service-1-deploy              Pulling image "quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:1d3b5b38c155375ead22a7a7dce941dc7d3a34f58c6d5f69c95d4c8da397bbc0"
117s        Normal   Pulled              pod/docker-service-1-deploy              Successfully pulled image "quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:1d3b5b38c155375ead22a7a7dce941dc7d3a34f58c6d5f69c95d4c8da397bbc0"
117s        Normal   Created             pod/docker-service-1-deploy              Created container deployment
117s        Normal   Started             pod/docker-service-1-deploy              Started container deployment
117s        Normal   Scheduled           pod/docker-service-1-sgzr2               Successfully assigned docker-app/docker-service-1-sgzr2 to crc-rk2fc-master-0109s        Normal   Pulling             pod/docker-service-1-sgzr2               Pulling image "ashwinprakash/docker-service@sha256:383dd7f0e828c43539ecc814bb3d968ac015c51b374ec6

*UI Steps :- *login to console on second tab by popping it out to new window, login with username:- developer, password:- developer , go to workloads-> pods -> docker-service-xxx -> events

To view the pods running under the namespace after the deployment

oc get pods

NAME         READY   STATUS      RESTARTS   AGE
docker-service-1-4v2z6    1/1     Running     0          97s
docker-service-1-deploy   0/1     Completed   0          110s

To check the logs of your application running in the pod

oc logs -f [pod_name]

oc logs -f docker-service-1-4v2z6

To view the service created for the deployed application

oc get svc

To create route for service discovery of the deployed application

oc expose svc/service_name eg: oc expose svc/docker-service
oc get route

NAME             HOST/PORT                                                                   PATH   SERVICES         PORT       TERMINATION   WILDCARD
docker-service   docker-service-myproject.2886795281-80-shadow04.environments.katacoda.com          docker-service   8080-tcp                 None

Curl the above hostname over http with uri of /employees to get the data from the actual microservice

curl http://docker-service-myproject.2886795281-80-shadow04.environments.katacoda.com/employees


[{"id":1,"firstName":"Pradeep","lastName":"Singh","emailId":"[email protected]"},{"id":2,"firstName":"Anand","lastName":"Zaveri","emailId":"[email protected]"},{"id":3,"firstName":"Akhilesh","lastName":"Juyal","emailId":"[email protected]"},{"id":4,"firstName":"Vaibhav","lastName":"Jha","emailId":"[email protected]"},{"id":5,"firstName":"Himanshu","lastName":"Sharma","emailId":"[email protected]"},{"id":6,"firstName":"Jignesh","lastName":"Mehta","emailId":"[email protected]"}]

To view all the deployment_configs

oc get dc

To view the details of the specific deployment_config

oc describe dc/docker-service

To delete the deployment

oc deploy dc/docker-service --cancel

To retry the deployment

oc deploy dc/docker-service --retry

Openshift Advance Features

To roll-up or roll-down a pod of the same deployed application

oc edit dc/docker-service

spec:
  replicas: 1 #change the value depending on the no of pods you need

UI Steps:- you can also login to console username;- developer, password:- developer -> workloads -> deployment configs -> press the up arrow to scale upa nd down arrow to scale down- pretty cool eh

To create Config Map as environment variable in the container pod

oc create configmap boot-env-config --from-literal=special.employee='Pradeep Singh'

Note:- Above is imperative model direclty with command

oc get configmap

Edit the deployment config to read env variable from above config map

oc get dc/docker-service > dc.yaml Edit the dc.yaml to addd below section just after spec.containers.ports section- make sure to leave 2 spaces else it can break the yaml formatting


    spec:
      containers:
        - name: docker-service
          image: >-
            ashwinprakash/docker-service@sha256:625d1259944f6bb46c244bc96ef85bd977f078684f43726bd238d4a9b4a37b07
          ports:
            - containerPort: 8080
              protocol: TCP
          env:
          - name: SPECIAL_EMPLOYEE
            valueFrom:
              configMapKeyRef:
                name: boot-env-config
                key: special.employee

Now we apply the configuration to openshift

oc apply -f dc.yaml

Lets check the env variable in the pod

oc get pods | grep Running

docker-service-2-24glk    1/1     Running     0          17s

Lets login to the pod once its up (check with oc get pods - wait for 2 -5 mins for the pdo to be recreated after the apply command)

oc rsh docker-service-2-24glk

/usr/app # echo $SPECIAL_EMPLOYEE
Pradeep Singh

Use the same hostname which we got from oc get route and append the /specialEmp on the http protocl to fetch the same from the underlying container

curl http://docker-service-myproject.2886795281-80-shadow04.environments.katacoda.com/specialEmp

To create secret as environment variable like say to connect to a db from within the pod which we cannot store as a config map sourced from git

oc create secret generic boot-env-secret --from-literal=secret.special.employee=Himanshu
oc get secret

Edit the deployment config to read env variable from above secret

oc get dc/docker-service > dc.yaml Edit the dc.yaml to addd below section just after spec.containers.ports section- make sure to leave 2 spaces else it can break the yaml formatting


    spec:
      containers:
        - name: docker-service
          image: >-
            ashwinprakash/docker-service@sha256:625d1259944f6bb46c244bc96ef85bd977f078684f43726bd238d4a9b4a37b07
          ports:
            - containerPort: 8080
              protocol: TCP
          env:
          - name: SECRET_EMPLOYEE
            valueFrom:
              secretKeyRef:
                name: boot-env-secret
                key: secret.special.employee

Now we apply the configuration to openshift

oc apply -f dc.yaml

Wait for couple of minutes for the new pod to come up - check using oc get pods

Use the same hostname which we got from oc get route and append the /secretEmp on the http protocl to fetch the same from the underlying container

curl http://docker-service-myproject.2886795281-80-shadow04.environments.katacoda.com/secretEmp

Himanshu

UI Steps :- for secrets- go to workloads-> secrets in the openshift ui for config maps got to workloads-> config maps

We can create the config map and secret in the same deployment by making the change in the deployment config as shown below

    spec:
      containers:
        - name: docker-service
          image: >-
            ashwinprakash/docker-service@sha256:625d1259944f6bb46c244bc96ef85bd977f078684f43726bd238d4a9b4a37b07
          ports:
            - containerPort: 8080
              protocol: TCP
          env:
		  - name: SPECIAL_EMPLOYEE
            valueFrom:
              configMapKeyRef:
                name: boot-env-config
                key: special.employee
          - name: SECRET_EMPLOYEE
            valueFrom:
              secretKeyRef:
                name: boot-env-secret
                key: secret.employee

To create Blue Green Deployment

oc new-app adi4196/docker-demo:v1 --name=blueversion
oc new-app adi4196/docker-demo:v2 --name=greenversion
oc expose svc/blueversion --name=bluegreen
oc get route

Hit the browser with hostname/getVersion Result :- "Old version is Running"

oc patch route/bluegreen -p '{"spec":{"to":{"name":"greenversion"}}}'

Hit the browser with hostname/getVersion Result :- "New version is Running"

Note :- hostname will be the same so second time only need to hit the same url

Name		Name	Last commit message	Last commit date
Latest commit History 17 Commits
bin		bin
gradle/wrapper		gradle/wrapper
src		src
.gitignore		.gitignore
Dockerfile		Dockerfile
README.md		README.md
build.gradle		build.gradle
gradlew		gradlew
gradlew.bat		gradlew.bat
openshift lab.pdf		openshift lab.pdf
settings.gradle		settings.gradle

aditya4196/containerization-basics

Folders and files

Latest commit

History

Repository files navigation