Adding kubernetes component

This section describes how to add a kubernetes component to a devfile. A complex component type that allows to apply configuration from a list of Kubernetes or OpenShift components.

Prerequisites

• Adding schema version

• Adding a name

• Adding components

Procedure

1. Define a component using the type kubernetes.

2. The content can be provided through the reference attribute, which points to the file with the component content.

   Adding kubernetes component using the reference attribute

   devfile.yaml

   components:
     - name: mysql
       kubernetes:
         reference: petclinic.yaml
         selector:
           app.kubernetes.io/name: mysql
           app.kubernetes.io/component: database
           app.kubernetes.io/part-of: petclinic
   

3. Alternatively, to post a devfile with such components to REST API, the contents of the Kubernetes or OpenShift list can be embedded into the devfile using the referenceContent field:

   Adding kubernetes component using the referenceContent attribute

   devfile.yaml

   components:
     - name: mysql
       kubernetes:
         reference: petclinic.yaml
         referenceContent: |
               kind: List
               items:
               -
                 apiVersion: v1
                 kind: Pod
                 metadata:
                 name: ws
                 spec:
                 containers:
                 ... etc
   

4. Overriding container entrypoints. As with the container component, it is possible to override the entrypoint of the containers contained in the Kubernetes or OpenShift list using the command and args properties (as understood by Kubernetes).

   There can be more containers in the list (contained in Pods or Pod templates of deployments). It is therefore necessary to select which containers to apply the entrypoint changes to as follows:

   Overriding container entrypoints

   devfile.yaml

   components:
     - name: appDeployment
       kubernetes:
         reference: app-deployment.yaml
         entrypoints:
         - parentName: mysqlServer
           command: ['sleep']
           args: ['infinity']
         - parentSelector:
           app: prometheus
           args: ['-f', '/opt/app/prometheus-config.yaml']
   

   The entrypoints list contains constraints for picking the containers along with the command and args parameters to apply to them. In the example above, the constraint is parentName: mysqlServer, which will cause the command to be applied to all containers defined in any parent object called mysqlServer. The parent object is assumed to be a top level object in the list defined in the referenced file, which is app-deployment.yaml in the example above.

   Other types of constraints (and their combinations) are possible:

   • containerName the name of the container

   • parentName the name of the parent object that (indirectly) contains the containers to override

   • parentSelector the set of labels the parent object needs to have

   A combination of these constraints can be used to precisely locate the containers inside the referenced Kubernetes list.

5. Overriding container environment variables

   To provision or override entrypoints in a Kubernetes or OpensShift component, configure it in the following way:

   Overriding container environment variables

   devfile.yaml

   components:
     - name: appDeployment
       kubernetes:
         reference: app-deployment.yaml
         env:
           - name: ENV_VAR
             value: value
   

   This is useful for temporary content or without access to editing the referenced content. The specified environment variables are provisioned into each init container and containers inside all Pods and Deployments.

6. Specifying mount-source option

   To specify a project sources directory mount into container(s), use the mountSources parameter:

   Specifying mount-source option

   devfile.yaml

   components:
     - name: appDeployment
       kubernetes:
         reference: app-deployment.yaml
         mountSources: true
   

   If enabled, project sources mounts will be applied to every container of the given component. This parameter is also applicable for plugin type components.

Additional resources

• API reference

• Devfile samples