How to deploy an image from Scaleway Container Registry to Kubernetes Kapsule

In this how-to guide you learn how to create and push a container image to the Scaleway Container Registry and how to use it on Kubernetes Kapsule.

A container image consists of several bundled files, which encapsulate an application. This image can be built on a local machine, uploaded to the image registry, and then deployed on various Kubernetes pods with Kapsule. Kapsule is the managed Kubernetes service provided by Scaleway. In this tutorial, we use Docker to build the containers.

The generated Docker images are stored in a private Docker registry using the Scaleway Container Registry product.

Before you start

To complete the actions presented below, you must have:

• A Scaleway account logged into the console
• Owner status or IAM permissions allowing you to perform actions in the intended Organization
• A valid API key
• Created a Container Registry namespace with a private privacy policy
• Created a Kubernetes Kapsule cluster and downloaded and configured the corresponding .kubeconfig file
• Installed Docker and kubectl on your local computer

How to push an image to the Scaleway Container Registry

1. Open a terminal window on your local computer.
2. Check that all required files are available to build the container image by running the ls -l command in the directory of your project:

   ls -l
   total 32
   -rw-r--r--  1 myuser  staff   903 Oct 14 12:19 Dockerfile
   -rw-r--r--  1 myuser  staff  1080 Oct 14 12:19 LICENSE
   -rw-r--r--  1 myuser  staff   476 Oct 14 12:19 Makefile
   -rw-r--r--  1 myuser  staff  1721 Oct 14 12:19 README.md
   drwxr-xr-x  3 myuser  staff    96 Oct 14 12:19 patches
   

3. Use the following commands to build the Docker container image locally before pushing it to your private Container Registry. The parameter -t configures the tags of the container:

   docker build -t mycontainer:latest .
   

   Sending build context to Docker daemon  197.6kB
   ...
   ...
   ...
   ---> c427b132b5fc
   Successfully built c427b132b5fc
   Successfully tagged mycontainer:latest
   

4. Check that the image has been added to the local Docker installation by running the docker images command. Your newly created container image will be displayed in the list of available images:

   docker images
   REPOSITORY                                             TAG                 IMAGE ID            CREATED             SIZE
   mycontainer                                            latest              c427b132b5fc        22 minutes ago      1.24GB
   

5. Log into your Container Registry. The endpoint (for example: rg.fr-par.scw.cloud/myregistry) of your Container Registry is available from the Scaleway console and depends on your configuration:

   docker login rg.fr-par.scw.cloud/myregistry -u nologin -p $SCW_SECRET_KEY
   

   A Login Succeeded message displays once logged in.
6. Tag the image using the docker tag command. Make sure to replace the URL of the registry with your personal endpoint:

   docker tag mycontainer:latest rg.fr-par.scw.cloud/myregistry/mycontainer:latest
   

7. Push the image to the registry using the docker push command:

   docker push rg.fr-par.scw.cloud/myregistry/mycontainer:latest
   

   ...
   ...
   a26724645421: Pushed
   a30b835850bf: Pushed
   latest: digest: sha256:690d70e8f26cb772916c64244c86701c50f2764e42c668d4d0aaf039a9d62b47 size: 4067
   

How to create an Image Pull Secret

To deploy the previously created container image in a Kapsule cluster, you need to create an Image Pull Secret. This allows your Kapsule cluster to connect to your Container Registry and pull the image itself. For this, your API secret key is required.

1. Run kubectl to define a secret called registry-secret using the $SCW_SECRET_KEY variable as follows:

   kubectl create secret docker-registry registry-secret --docker-server=rg.fr-par.scw.cloud --docker-username=my-registry-namespace --docker-password=$SCW_SECRET_KEY
   

   Important

   Replace the value for docker-server with the address of your Container Registry (e.g. if it is in the Amsterdam or Warsaw regions), and the value for docker-username with the name of your Container Registry namespace.

2. Display the generated secret with the kubectl get secret command. The flag --output=yaml will return the output formatted in YAML:

   kubectl get secret registry-secret --output=yaml
   

   apiVersion: v1
   data:
     .dockerconfigjson: eyJhdXRocyI6eyJyZy5mci1wYXIuc2N3LmNsb3VkIjp7InVzZXJuYW1lIjoibXl1c2VyIiwicGFzc3dvcmQiOiJkYTI0N2E0Yi1hZDk4LTQ2NGYtOTdhYy1hOGIwNTZmYjU2NWYiLCJlbWFpbCI6Im15QGVtYWlsLmNvbSIsImF1dGgiOiJiWGwxYzJWeU9tUmhNalEzWVRSaUxXRmtPVGd0TkRZMFppMDVOMkZqTFdFNFlqQTFObVppTlRZMVpnPT0ifX19
   kind: Secret
   metadata:
     creationTimestamp: 2019-10-14T12:23:32Z
     name: registry-secret
     namespace: default
     resourceVersion: "2977046288"
     selfLink: /api/v1/namespaces/default/secrets/registry-secret
     uid: 85a69713-f239-43f3-8f00-36603c794557
   type: kubernetes.io/dockerconfigjson
   

How to create a deployment for the container

1. Create a file deployment.yaml and open it in a text editor, e.g. nano:

   nano deployment.yaml
   

2. Copy the following content into it, save the file and quit the text editor.

   Remember to replace the image name rg.fr-par.scw.cloud/myregistry/mycontainer:latest and registry secret registry-secret with the values you previously defined.

     apiVersion: apps/v1
     kind: Deployment
     metadata:
       name: mydeployment
       labels:
         app: mydeployment
     spec:
       replicas: 2
       selector:
         matchLabels:
           app: mydeployment
       template:
         metadata:
           labels:
             app: mydeployment
         spec:
           containers:
             - name: mycontainer
               image: rg.fr-par.scw.cloud/myregistry/mycontainer:latest
           imagePullSecrets:
             - name: registry-secret
   

   Note

   In the configuration above, the secret and deployments are in the same namespace.

3. Run kubectl apply to apply the deployment to the cluster:

   kubectl apply -f deployment.yaml
   

4. Use the kubectl get pods command to check the status of the deployment:

   kubectl get pods
   

   NAME                            READY   STATUS             RESTARTS   AGE
   mydeployment-64c9fdd66c-66mrq   1/1     Running            0          2m
   mydeployment-64c9fdd66c-pwhl9   1/1     running            0          2m
   

As you can see in the output above, the image has been pulled successfully from the registry and two replicas of it are running on the Kapsule cluster.

For more information how to use your Container Registry with Kubernetes, refer to the official documentation.