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Thursday, August 10, 2017

Kompose Helps Developers Move Docker Compose Files to Kubernetes

Editor's note: today's post is by Charlie Drage, Software Engineer at Red Hat giving an update about the Kubernetes project Kompose. 

I'm pleased to announce that Kompose, a conversion tool for developers to transition Docker Compose applications to Kubernetes, has graduated from the Kubernetes Incubator to become an official part of the project.

Since our first commit on June 27, 2016, Kompose has achieved 13 releases over 851 commits, gaining 21 contributors since the inception of the project. Our work started at Skippbox (now part of Bitnami) and grew through contributions from Google and Red Hat.

The Kubernetes Incubator allowed contributors to get to know each other across companies, as well as collaborate effectively under guidance from Kubernetes contributors and maintainers. Our incubation led to the development and release of a new and useful tool for the Kubernetes ecosystem.

We’ve created a reliable, scalable Kubernetes environment from an initial Docker Compose file. We worked hard to convert as many keys as possible to their Kubernetes equivalent. Running a single command gets you up and running on Kubernetes:  kompose up.

We couldn’t have done it without feedback and contributions from the community!

If you haven’t yet tried Kompose on GitHub check it out!


Kubernetes guestbook

The go-to example for Kubernetes is the famous guestbook, which we use as a base for conversion.

Here is an example from the official kompose.io site, starting with a simple Docker Compose file.

First, we’ll retrieve the file:

$ wget https://raw.githubusercontent.com/kubernetes/kompose/master/examples/docker-compose.yaml
You can test it out by first deploying to Docker Compose:

$ docker-compose up -d
Creating network "examples_default" with the default driver
Creating examples_redis-slave_1
Creating examples_frontend_1
Creating examples_redis-master_1
And when you’re ready to deploy to Kubernetes:

$ kompose up

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 Successfully created Service: redis          
INFO Successfully created Service: web            
INFO Successfully created Deployment: redis       
INFO Successfully created Deployment: web         

Your application has been deployed to Kubernetes. You can run kubectl get deployment,svc,pods,pvc for details
Check out other examples of what Kompose can do.
Converting to alternative Kubernetes controllers

Kompose can also convert to specific Kubernetes controllers with the use of flags:
$ kompose convert --help
Usage:
 kompose convert [file] [flags]

Kubernetes Flags:
     --daemon-set               Generate a Kubernetes daemonset object
 -d, --deployment               Generate a Kubernetes deployment object
 -c, --chart                    Create a Helm chart for converted objects
     --replication-controller   Generate a Kubernetes replication controller object
For example, let’s convert our guestbook example to a DaemonSet:

$ kompose convert --daemon-set
INFO Kubernetes file "frontend-service.yaml" created
INFO Kubernetes file "redis-master-service.yaml" created
INFO Kubernetes file "redis-slave-service.yaml" created
INFO Kubernetes file "frontend-daemonset.yaml" created
INFO Kubernetes file "redis-master-daemonset.yaml" created
INFO Kubernetes file "redis-slave-daemonset.yaml" created
Key Kompose 1.0 features

With our graduation, comes the release of Kompose 1.0.0, here’s what’s new:
  • Docker Compose Version 3: Kompose now supports Docker Compose Version 3. New keys such as ‘deploy’ now convert to their Kubernetes equivalent.
  • Docker Push and Build Support: When you supply a ‘build’ key within your `docker-compose.yaml` file, Kompose will automatically build and push the image to the respective Docker repository for Kubernetes to consume.
  • New Keys: With the addition of version 3 support, new keys such as pid and deploy are supported. For full details on what Kompose supports, view our conversion document.
  • Bug Fixes: In every release we fix any bugs related to edge-cases when converting. This release fixes issues relating to converting volumes with ‘./’ in the target name.
What’s ahead?

As we continue development, we will strive to convert as many Docker Compose keys as possible for all future and current Docker Compose releases, converting each one to their Kubernetes equivalent. All future releases will be backwards-compatible.



--Charlie Drage, Software Engineer, Red Hat

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