Chapter 8. Caching images for faster workspace start

Procedure

1. Get the list of relevant container images.

   Example 8.1. Getting the list of all relevant images for CodeReady Workspaces

   $ curl -sSLo- https://raw.githubusercontent.com/redhat-developer/codeready-workspaces-operator/crw-2.8-rhel-8/manifests/codeready-workspaces.csv.yaml | \
     yq -r '.spec.relatedImages[]'

2. Exclude from the list the container images not containing the sleep command.

   Example 8.2. Images incompatibles with {image-puller-short}, missing the sleep command

   • FROM scratch images.
   • che-machine-exec
3. Exclude from the list the container images mounting volumes in Dockerfile.

Procedure

1. To define the minimal value for CACHING_MEMORY_REQUEST or CACHING_MEMORY_LIMIT, consider the necessary amount of memory required to run each of the container images to pull.

2. To define the maximal value for CACHING_MEMORY_REQUEST or CACHING_MEMORY_LIMIT, consider the total memory allocated to the DaemonSet Pods in the cluster:

   (memory limit) * (number of images) * (number of nodes in the cluster)

   Pulling 5 images on 20 nodes, with a container memory limit of 20Mi requires 2000Mi of memory.

Procedure

1. Edit the CheCluster Custom Resource and set .spec.imagePuller.enable to true

   Example 8.3. Enabling Image Puller in the CheCluster Custom Resource

   apiVersion: org.eclipse.che/v1
   kind: CheCluster
   metadata:
     name: codeready-workspaces
   spec:
     # ...
     imagePuller:
       enable: true

   Uninstalling Image Puller using CodeReady Workspaces Operator

   • Edit the CheCluster Custom Resource and set .spec.imagePuller.enable to false.

2. Edit the CheCluster Custom Resource and set the .spec.imagePuller.spec to configure the optional Image Puller parameters for the CodeReady Workspaces Operator.

   Example 8.4. Configuring Image Puller in the CheCluster Custom Resource

   apiVersion: org.eclipse.che/v1
   kind: CheCluster
   metadata:
     name: codeready-workspaces
   spec:
     ...
     imagePuller:
       enable: true
       spec:
           configMapName: <kubernetes-image-puller>
           daemonsetName: <kubernetes-image-puller>
           deploymentName: <kubernetes-image-puller>
           images: <{image-puller-images}>

Verification steps

1. OpenShift creates a {image-puller-operator-id} Subscription.

2. The eclipse-che namespace contains a community supported Kubernetes Image Puller Operator ClusterServiceVersion:

   $ oc get clusterserviceversions

3. The eclipse-che namespace contains these deployments: kubernetes-image-puller and {image-puller-deployment-id}.

   $ oc get deployments

4. The community supported Kubernetes Image Puller Operator creates a KubernetesImagePuller Custom Resource:

   $ oc get kubernetesimagepullers

Procedure

1. To create an OpenShift project <kubernetes-image-puller> to host the Image Puller, open the OpenShift web console, navigate to the Home → Projects section and click Create Project.

2. Specify the project details:

   • Name: <kubernetes-image-puller>
   • Display Name: <Image Puller>
   • Description: <Kubernetes Image Puller>
3. Navigate to Operators → OperatorHub.
4. Use the Filter by keyword box to search for community supported Kubernetes Image Puller Operator. Click the community supported Kubernetes Image Puller Operator.
5. Read the description of the Operator. Click Continue → Install.
6. Select A specific project on the cluster for the Installation Mode. In the drop-down find the OpenShift project <kubernetes-image-puller>. Click Subscribe.
7. Wait for the community supported Kubernetes Image Puller Operator to install. Click the KubernetesImagePuller → Create instance.
8. In a redirected window with a YAML editor, make modifications to the KubernetesImagePuller Custom Resource and click Create.
9. Navigate to the Workloads and Pods menu in the <kubernetes-image-puller> OpenShift project. Verify that the Image Puller is available.

Procedure

1. Clone the Image Puller repository and get in the directory containing the OpenShift templates:

   $ git clone https://github.com/che-incubator/kubernetes-image-puller
   $ cd kubernetes-image-puller/deploy/openshift

2. Configure the app.yaml, configmap.yaml and serviceaccount.yaml OpenShift templates using following parameters:

   Table 8.2. Image Puller OpenShift templates parameters in app.yaml

   Value	Usage	Default
   DEPLOYMENT_NAME	The value of DEPLOYMENT_NAME in the ConfigMap	kubernetes-image-puller
   IMAGE	Image used for the kubernetes-image-puller deployment	registry.redhat.io/codeready-workspaces/imagepuller-rhel8:2.8
   IMAGE_TAG	The image tag to pull	latest
   SERVICEACCOUNT_NAME	The name of the ServiceAccount created and used by the deployment	{image-puller-serviceaccount-name}

   Table 8.3. Image Puller OpenShift templates parameters in configmap.yaml

   Value	Usage	Default
   CACHING_CPU_LIMIT	The value of CACHING_CPU_LIMIT in the ConfigMap	.2
   CACHING_CPU_REQUEST	The value of CACHING_CPU_REQUEST in the ConfigMap	.05
   CACHING_INTERVAL_HOURS	The value of CACHING_INTERVAL_HOURS in the ConfigMap	"1"
   CACHING_MEMORY_LIMIT	The value of CACHING_MEMORY_LIMIT in the ConfigMap	"20Mi"`
   CACHING_MEMORY_REQUEST	The value of CACHING_MEMORY_REQUEST in the ConfigMap	"10Mi"
   DAEMONSET_NAME	The value of DAEMONSET_NAME in the ConfigMap	kubernetes-image-puller
   DEPLOYMENT_NAME	The value of DEPLOYMENT_NAME in the ConfigMap	kubernetes-image-puller
   IMAGES	The value of IMAGES in the ConfigMap	{image-puller-images}
   NODE_SELECTOR	The value of NODE_SELECTOR in the ConfigMap	"{}"

   Table 8.4. Image Puller OpenShift templates parameters in serviceaccount.yaml

   Value	Usage	Default
   SERVICEACCOUNT_NAME	The name of the ServiceAccount created and used by the deployment	{image-puller-serviceaccount-name}

3. Create an OpenShift project to host the Image Puller:

   $ oc new-project <kubernetes-image-puller>

4. Process and apply the templates to install the puller:

   $ oc process -f serviceaccount.yaml | oc apply -f -
   $ oc process -f configmap.yaml | oc apply -f -
   $ oc process -f app.yaml | oc apply -f -

Verification steps

1. Verify the existence of a <kubernetes-image-puller> deployment and a <kubernetes-image-puller> DaemonSet. The DaemonSet needs to have a Pod for each node in the cluster:

   $ oc get deployment,daemonset,pod --namespace <kubernetes-image-puller>

2. Verify the values of the <kubernetes-image-puller> ConfigMap.

   $ oc get configmap <kubernetes-image-puller> --output yaml