How to use the command 'kompose' (with examples)

This article will guide you through using the command ‘kompose’ for various use cases. ‘kompose’ is a tool that allows you to convert docker-compose applications into Kubernetes resources. It is a widely used tool in the Kubernetes ecosystem and can simplify the process of deploying and managing applications on Kubernetes.

Use case 1: Deploy a dockerized application to Kubernetes

Code:

kompose up -f docker-compose.yml

Motivation:

The motivation behind deploying a dockerized application to Kubernetes is to take advantage of the scalability and resilience features provided by Kubernetes. By deploying a dockerized application to Kubernetes, you can easily manage multiple instances of the application, load balance traffic, and provide high availability.

Explanation:

• kompose: The main command for using ‘kompose’ tool.
• up: The ‘up’ command is used to create Kubernetes resources and deploy the application to the Kubernetes cluster.
• -f docker-compose.yml: Specifies the path to the docker-compose file that needs to be converted and deployed.

Example output:

INFO We are going to create Kubernetes Deployments, Services and PersistentVolumeClaims for your Dockerized application. If you need different kind of resources, use the 'kompose convert' and 'kubectl create -f' commands instead.

INFO Deploying application in namespace default

INFO Successfully created Service: myapp
INFO Successfully created Deployment: myapp

INFO Your application has been deployed to Kubernetes. You can run 'kubectl get deployment,svc,pods,job' for details.

Use case 2: Delete instantiated services/deployments from Kubernetes

Code:

kompose down -f docker-compose.yml

Motivation:

The motivation behind deleting instantiated services/deployments from Kubernetes is to free up resources and clean up any unused and unnecessary deployments. This is particularly useful when you need to stop and remove a running application from the Kubernetes cluster.

Explanation:

• kompose: The main command for using ‘kompose’ tool.
• down: The ‘down’ command is used to delete the Kubernetes resources and stop the application.
• -f docker-compose.yml: Specifies the path to the docker-compose file that needs to be converted and deleted.

Example output:

INFO Deleting application in namespace default

INFO Successfully deleted Service: myapp
INFO Successfully deleted Deployment: myapp

INFO Your application has been deleted from Kubernetes.

Use case 3: Convert a docker-compose file into Kubernetes resources file

Code:

kompose convert -f docker-compose.yml

Motivation:

The motivation behind converting a docker-compose file into a Kubernetes resources file is to make it easier to deploy and manage applications on Kubernetes. By converting the docker-compose file, you can leverage the Kubernetes ecosystem and take advantage of its features such as scaling, load balancing, and self-healing.

Explanation:

• kompose: The main command for using ‘kompose’ tool.
• convert: The ‘convert’ command is used to convert a docker-compose file into Kubernetes resources.
• -f docker-compose.yml: Specifies the path to the docker-compose file that needs to be converted.

Example output:

apiVersion: v1
kind: Service
metadata:
  labels:
    io.kompose.service: myapp
  name: myapp
spec:
  ports:
  - name: "80"
    port: 80
    targetPort: 80
  selector:
    io.kompose.service: myapp
status:
  loadBalancer: {}
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    io.kompose.service: myapp
  name: myapp
spec:
  replicas: 1
  selector:
    matchLabels:
      io.kompose.service: myapp
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        io.kompose.service: myapp
    spec:
      containers:
      - image: myapp:latest
        name: myapp
        ports:
        - containerPort: 80
          name: "80"

Conclusion:

In this article, we have explored different use cases of the ‘kompose’ command. From deploying a dockerized application to Kubernetes, to deleting instantiated services and deployments, and converting docker-compose files into Kubernetes resources, ‘kompose’ proves to be a versatile and useful tool. By using ‘kompose’, developers can easily manage their applications on Kubernetes and take advantage of its powerful features.