Converting from Docker-Compose

The first step will be to install kompose and convert our docker-compose.yml to kubernetes yaml files.

Install kompose

> brew install kompose

Startup without Converting

For simple docker-compose files, we can skip the steps pf converting and start up directly using kompose up.

> kompose up

Exporting

For more complicated docker-compose files, we will need to export and then modify the converted files.

> kompose convert


$ kompose convert
WARN Volume mount on the host "/Users/john.mehan/projects/cloud/deployment/is-config/IND" isn't supported - ignoring path on the host 
INFO Kubernetes file "cloudservice-service.yaml" created 
INFO Kubernetes file "isservice-service.yaml" created 
INFO Kubernetes file "postgres-service.yaml" created 
INFO Kubernetes file "redis-service.yaml" created 
INFO Kubernetes file "cloudservice-deployment.yaml" created 
INFO Kubernetes file "isservice-deployment.yaml" created 
INFO Kubernetes file "isservice-claim0-persistentvolumeclaim.yaml" created 
INFO Kubernetes file "postgres-deployment.yaml" created 
INFO Kubernetes file "db-volume-persistentvolumeclaim.yaml" created 
INFO Kubernetes file "redis-deployment.yaml" created


Create Kubernetes pods in Cluster

We are using minkube for our cluster. Lets start by making sure it is running:

$ minikube start


Using the yaml files created by kompose export, lets create our pods:

$ kubectl create -f cloudservice-service.yaml,isservice-service.yaml,postgres-service.yaml,redis-service.yaml,cloudservice-deployment.yaml,isservice-deployment.yaml,isservice-claim0-persistentvolumeclaim.yaml,postgres-deployment.yaml,db-volume-persistentvolumeclaim.yaml,redis-deployment.yaml 

service/cloudservice created
service/isservice created
service/postgres created
service/redis created
deployment.extensions/cloudservice created
deployment.extensions/isservice created
persistentvolumeclaim/isservice-claim0 created
deployment.extensions/postgres created
persistentvolumeclaim/db-volume created
deployment.extensions/redis created

Pulling image from Docker Registry

Kubernetes will pull docker images from docker hub by default. For our own custom images, we will pull them from our local docker registry.

For this to work we need to

  • create a secret in the cluster that holds our authorization token
  • update our deployment yaml files to include this secret
  • setup an ssh tunnel between our localhost running docker registry and our cluster (minikube)

Create a Secret in the cluster that holds your authorization token

> kubectl create secret docker-registry regcred --docker-server=<your-registry-server> --docker-username=<your-name> --docker-password=<your-pword> --docker-email=<your-email>


$ kubectl create secret docker-registry regcred --docker-server=http://localhost:5000/ --docker-username=username --docker-password=password --docker-email=john.mehan@irdeto.com
secret/regcred created

Revise deployment.yaml files

Add imagePullSecrets section to your deployment yaml files:


imagePullSecrets:
- name: regcred

example:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
...
spec:
  replicas: 1
  strategy:
    type: Recreate
  template:
    metadata:
      creationTimestamp: null
      labels:
        io.kompose.service: isservice
    spec:
      containers:
      - image: localhost:5000/safa_is:0.1
        name: isservice
        ports:
        - containerPort: 8080
        resources: {}
        tty: true
        volumeMounts:
        - mountPath: /home/irdeto/CONF/ISF/IND
          name: is-volume
      restartPolicy: Always
      volumes:
      - name: is-volume
        persistentVolumeClaim:
          claimName: is-volume
      imagePullSecrets:
      - name: regcred
status: {}


Setup SSH Tunnel

We will setup an SSH Tunnel in order to allow kubernetes to pull images from our local docker registry.

$ ssh -i ~/.minikube/machines/minikube/id_rsa docker@$(minikube ip) -R 5000:localhost:5000

References

ReferenceURL
Translate docker compose to Kuberneteshttps://kubernetes.io/docs/tasks/configure-pod-container/translate-compose-kubernetes/
Kotacoda Kubernetes Playgroundhttps://www.katacoda.com/courses/kubernetes/playground
Pull an image from a Private Registryhttps://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/




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