Deployment to Kubernetes
Using the Codefresh GUI to deploy to a Kubernetes cluster
In this tutorial we will see how you can use Codefresh to deploy a Docker image to a Kubernetes cluster and also how to setup an automated pipeline to automatically redeploy it when the source code changes.
Even though, in this tutorial we use Codefresh to deploy docker images directly to the Kubernetes cluster, in production you will use Helm Charts provided by Eupraxia Labs. Helm is a package manager for Kubernetes that allows you to deploy multiple applications at once as a single entity (Helm Charts) and also perform rollbacks to previous versions. Like Kubernetes, Codefresh has native support for Helm deployments including a release dashboard.
Notice that for this tutorial we will use the GUI provided by Codefresh to both create the Kubernetes service inside the cluster and also to create the CI/CD pipeline that keeps it up to date. In a real world scenario it is best if you use Codefresh YAML which is much more powerful and flexible.
Codefresh also offers several alternative ways of deploying to Kubernetes.
At the end of this tutorial we will have a pipeline that
- checks out code from GitHub and creates a Docker image
- stores it in the internal Codefresh Docker registry
- Notifies the K8s cluster that a new version of the application is present. Kubernetes will pull the new image and deploy it.
It is assumed that:
- you have already added your K8s cluster into Codefresh
- you have already an application that has a Dockerfile. In not, see the previous tutorial
Notice that for this tutorial you don’t need a Kubernetes deployment file. Codefresh will create one for you via its friendly GUI. If you already have an existing deployment file for your own application, consult the main K8s documentation on how to use it.
Giving the Kubernetes cluster read access to the internal Codefresh registry
A Kubernetes cluster deploys applications by pulling images from a Docker registry. In most cases your Docker image will be on a private Docker registry. Therefore, you need to grant rights to the cluster so that it has read access to the images that are pushed on the Docker registry by Codefresh.
Each Codefresh account comes with its own built-in Docker registry, but by default this is not accessible externally. To make this registry “external” we need to declare it first as an integration.
Creating an API key for the Codefresh internal registry
Click User settings on the left sidebar. At the bottom of the User settings screen, click the button Generate at the Codefresh Registry section.
In the dialog that appears, enter a name for your key (this name doesn’t affect anything, it is just for you to remember the purpose of the key) and click the Create button. Your key will be generated. You can click the “eye” button inside the text field to view its full form.
Write down this token as it will never be visible again apart from this screen.
Making the internal Codefresh Registry available to your Kubernetes cluster
After you have the API key, go to your Account Configuration, by clicking on Account Settings on the left sidebar. On the first section called Integrations click the Configure button next to Docker Registry.
Then click the Add Registry button and select the Codefresh registry from the top down menu. Enter your Codefresh username in the respective field and enter the token that we created in the previous section.
Finally click the Test button to make sure that everything works ok, and then the Save button to apply your changes. The Codefresh Internal registry is now ready to be used by your Kubernetes cluster.
Deploying a Docker image to Kubernetes manually
Codefresh offers a dedicated GUI that allows you to deploy any Docker image to your cluster without writing any configuration files at all.
Click the Kubernetes button from the left side bar. The screen that appears is the Codefresh overview of your Kubernetes cluster that shows all your deployments (pods and namespaces)
Click the Add Service button on the top right. The screen that appears is a friendly UI that allows you to create a Kubernetes deployment (and associated service). You can also toggle the top right button to define a Kubernetes YAML yourself, but for the purposes of this tutorial we will only use the GUI.
The fields in this screen are:
- Cluster - select your cluster if you have more than one
- Namespace - select the namespace where the application will be deployed to.(default will work just fine).
- Service Name - enter any arbitrary name for your service
- replicas - how many replicas you want for resiliency. This affects pricing, so 1 is a good value for a demo
- Expose port - check it so that your application is available outside the cluster
- Image - Enter the fully qualified name of your Docker image
- Image pull request - Select the Codefresh registry and create a pull secret for it
- Internal ports - which port is exposed from your application. The example Python app we deploy, exposes 5000
From the same screen you can also define environment variables and cpu/mem limits.
You can see the full name of the Docker image, in the Images tab of the Codefresh GUI of your build.
By default, Codefresh appends the branch name of a git commit to the resulting Docker image. This is why in the Image field we used the branch name as tag
Do not use
latestfor your deployments. This doesn’t help you to understand which version is deployed. Use either branch names or even better git hashes so that you know exactly what is deployed on your Kubernetes cluster. Notice also that the YML Codefresh is creating has an image pull policy of
always, so the cluster will always redeploy the latest image even if it has the same name as the previous one.
Finally click the deploy button. Codefresh will create a Kubernetes YAML file behind the scenes and apply it to your Kubernetes cluster. The cluster will contact the Codefresh registry and pull the image. The cluster will then create all the needed resources (service, deployments, pods) in order to make the application available.
You can watch the status of the deployment right from the Codefresh UI.
Once the deployment is complete, you will also see the public URL of the application. You can visit it in the browser and see the application running.
This concludes the manual deployment. We deployed a Docker image from Codefresh to a Kubernetes cluster without writing any YAML files at all! The next step is to automate this process so that every time a commit happens in git, the application will be redeployed.
Automating deployments to Kubernetes
The application is now running successfully in the Kubernetes cluster. We will setup a pipeline in Codefresh so that any commits that happen in GitHub, are automatically redeploying the application, giving us a true CI/CD pipeline.
To do this, we will add two extra steps in the basic pipeline created in the previous tutorial.
First, we will make sure that the Docker image created is sent to the registry. In the pipeline definition expand the Push to Registry section and make sure that the Codefresh Registry is selected from the popup menu
Next expand the Deploy Script stage. From the popup menu select Kubernetes and fill the details of the service.
Notice that by default Codefresh tags Docker images with the name of the GIT branch they were created from.
In the example above we use the
production branch so that the name of the Docker image matches the one
that we defined in Kubernetes in the previous section.
Once all the details are filled in, click the Save button.
Now we will change the application in the production branch and commit/push the change to Git.
Codefresh will pick the change automatically and trigger a new build that deploys the new version
Once the build is complete, if you visit again the URL you will see your change applied.
You now have a complete CI/CD pipeline in Codefresh for fully automated builds to Kubernetes!