Adding kubernetes component to a devfile

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
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.

    Example 1. Adding kubernetes component using the reference attribute
      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:

    Example 2. Adding kubernetes component using the referenceContent attribute
      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:

    Example 3. Overriding container entrypoints
      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:

    Example 4. Overriding container environment variables
      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:

    Example 5. Specifying mount-source option
       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.