MicroShift is Technology Preview software only.
For more information about the support scope of Red Hat Technology Preview software, see Technology Preview Support Scope.Chapter 2. How Operators work with Red Hat build of MicroShift
You can use Operators with Red Hat build of MicroShift to create applications that monitor the running services in your cluster. Operators can manage applications and their resources, such as deploying a database or message bus. As customized software running inside your cluster, Operators can be used to implement and automate common operations.
Operators offer a more localized configuration experience and integrate with Kubernetes APIs and CLI tools such as kubectl and oc. Operators are designed specifically for your applications. Operators enable you to configure components instead of modifying a global configuration file.
Red Hat build of MicroShift applications are generally expected to be deployed in static environments. However, Operators are available if helpful in your use case. To determine an Operator’s compatibility with Red Hat build of MicroShift, check the Operator’s documentation.
2.1. How to install Operators in Red Hat build of MicroShift
To minimize the footprint of Red Hat build of MicroShift, Operators are installed directly with manifests instead of using the Operator Lifecycle Manager (OLM). The following examples provide instructions on how you can use the kustomize configuration management tool with Red Hat build of MicroShift to deploy an application. Use the same steps to install Operators with manifests.
2.1.1. How manifests work with kustomize
The kustomize configuration management tool is integrated with Red Hat build of MicroShift. At every start, Red Hat build of MicroShift searches the /etc/microshift/manifests and /usr/lib/microshift/ manifest directories for a kustomization.yaml file. If it finds one, Red Hat build of MicroShift automatically runs the equivalent of the kubectl apply -k command to apply the identified manifests to the cluster.
| Location | Intent |
|---|---|
|
| Read-write location for configuration management systems or development. |
|
| Read-only location for embedding configuration manifests on OSTree-based systems. |
2.1.2. Using manifests example
This example demonstrates automatic deployment of a BusyBox container using kustomize manifests in the /etc/microshift/manifests directory.
Procedure
Create the BusyBox manifest files by running the following commands:
Define the directory location:
$ MANIFEST_DIR=/etc/microshift/manifests
Make the directory:
$ sudo mkdir -p ${MANIFEST_DIR}Place the YAML file in the directory:
$ sudo tee ${MANIFEST_DIR}/busybox.yaml &>/dev/null <<EOF apiVersion: v1 kind: Namespace metadata: name: busybox --- apiVersion: apps/v1 kind: Deployment metadata: name: busybox-deployment spec: selector: matchLabels: app: busybox template: metadata: labels: app: busybox spec: containers: - name: busybox image: BUSYBOX_IMAGE command: - sleep - "3600" EOF
Next, create the
kustomizemanifest files by running the following commands:Place the YAML file in the directory:
$ sudo tee ${MANIFEST_DIR}/kustomization.yaml &>/dev/null <<EOF --- apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization namespace: busybox resources: - busybox.yaml images: - name: BUSYBOX_IMAGE newName: registry.k8s.io/busybox EOF
Restart Red Hat build of MicroShift to apply the manifests by running the following command:
$ sudo systemctl restart microshift
Apply the manifests and start the
busyboxpod by running the following command:$ oc get pods -n busybox
