9 Using Operators with Kubernetes
Important:
The software described in this documentation is either in Extended Support or Sustaining Support. See Oracle Open Source Support Policies for more information.
We recommend that you upgrade the software described by this documentation as soon as possible.
This chapter discusses how to install and use the Operator Lifecycle Manager module for Oracle Cloud Native Environment to install and manage operators in a Kubernetes cluster.
A Kubernetes operator is a design pattern that allows you to write code to automate tasks and extend Kubernetes. It is a set of concepts you can use to define a service for Kubernetes and helps to automate administrative services in Kubernetes.
The Operator Lifecycle Manager module installs an instance Operator Lifecycle Manager into a Kubernetes cluster, which you can use to manage the installation and lifecycle management of operators in a Kubernetes cluster. The Operator Lifecycle Manager is essentially a package manager that interacts with operator registries. For more information about the Operator Lifecycle Manager, see the upstream documentation at:
https://olm.operatorframework.io/
OperatorHub is an operator registry that contains upstream Kubernetes operators that you can use to deploy operators in your cluster. The OperatorHub is at:
Operator Lifecycle Manager in many ways performs the same tasks as Helm. A major additional feature that Operator Lifecycle Manager provides is that it has built-in support to validate Custom Resource Definitions (CRDs) inside Kubernetes software. Operators with CRDs can use these to make sure dependencies are met and no interfaces are duplicated. Otherwise, Operator Lifecycle Manager manages deployments in a similar way to Helm.
Installing the Operator Lifecycle Manager Module
The Operator Lifecycle Manager is installed into a Kubernetes cluster as an Oracle Cloud Native Environment module.
To install the Operator Lifecycle Manager module:
-
If you do not already have the Helm module installed in the cluster, you must install it. On the operator node, use the
olcnectl module create
command to create the Helm module. Specify the name of the Kubernetes module with the--helm-kubernetes-module
option.olcnectl module create \ --environment-name myenvironment \ --module helm \ --name myhelm \ --helm-kubernetes-module mycluster
Use the
olcnectl module install
command to install the Helm module:olcnectl module install \ --environment-name myenvironment \ --name myhelm
-
Use the
olcnectl module create
command to create the Operator Lifecycle Manager module. Specify the name of the Helm module with the--olm-helm-module
option.olcnectl module create \ --environment-name myenvironment \ --module operator-lifecycle-manager \ --name myolm \ --olm-helm-module myhelm
-
Use the
olcnectl module install
command to install the Operator Lifecycle Manager module:olcnectl module install \ --environment-name myenvironment \ --name myolm
The Operator Lifecycle Manager module is deployed and the required containers are running in the
operator-lifecycle-manager
namespace.
Verifying the Operator Lifecycle Manager Module Deployment
You can verify the Operator Lifecycle Manager module is deployed and
the required deployments are running in the
operator-lifecycle-manager
namespace. To verify
the containers are deployed, use the kubectl
command on a control plane node.
To verify the required containers are running, list the
deployments running in the
operator-lifecycle-manager
namespace. You
should see similar results to those shown here:
kubectl get deploy -n operator-lifecycle-manager NAME READY UP-TO-DATE AVAILABLE AGE catalog-operator 1/1 1 1 2m36s olm-operator 1/1 1 1 2m36s packageserver 2/2 2 2 2m30s
You can also review information about the Operator Lifecycle Manager module and its properties.
Use the olcnectl module report
command to
review information about the module.
For example, use the following command to review the
Operator Lifecycle Manager module named myolm
in
myenvironment
:
olcnectl module report \ --environment-name myenvironment \ --name myolm \ --children
For more information on the syntax for the olcnectl
module report
command, see Platform Command-Line Interface.
Listing Operator Registries
You can show the available operator registries using the
kubectl
command on a control plane node:
kubectl get catalogsource -n operator-lifecycle-manager NAME DISPLAY TYPE PUBLISHER AGE operatorhubio-catalog Community Operators grpc OperatorHub.io 3m35s
The OperatorHub registry is shown in the output. This is the default operator registry.
The OperatorHub provides examples of the text to use for your operator manifest files. On each operator's page on OperatorHub, there are example YAML files to create operator manifest files.
Installing Operators
To see all the operators that can be installed, use the
kubectl
command on a control plane node:
kubectl get packagemanifest NAME CATALOG AGE vault Community Operators 3m22s submariner Community Operators 3m22s credstash-operator Community Operators 3m22s eunomia Community Operators 3m22s ibm-block-csi-operator-community Community Operators 3m22s ...
A list of the upstream operators available on OperatorHub are displayed. These are all available to be installed by the Operator Lifecycle Manager.
When you have decided on the operator name and catalog, you need
to create the Kubernetes resources that tell Operator Lifecycle Manager how to
install the operator. Two resources must be created: an
OperatorGroup
and a
Subscription
. If a new namespace is being
created, you can create the Namespace
in the
same operator manifest file.
You can download starter operator manifest files for operators from the OperatorHub.
This example shows you how to create an etcd
operator which is pulled from the OperatorHub.
To create an operator:
-
In a web browser, go to the OperatorHub and find the name of the operator you want to install. The OperatorHub is at:
This example uses the
etcd
operator at:https://operatorhub.io/operator/etcd
Click Install.
A dialog is displayed that shows the
kubectl create
command to deploy the operator. For example:kubectl create -f https://operatorhub.io/install/etcd.yaml
Copy the URL in this command that contains the operator manifest YAML file.
-
On a control plane node, download the
etcd
operator manifest YAML file from the OperatorHub:curl --remote-name https://operatorhub.io/install/etcd.yaml
-
You can edit this manifest YAML file to suit your needs. At the time of writing, this file contained the information required to create a
Namespace
,OperatorGroup
andSubscription
for theetcd
operator:apiVersion: v1 kind: Namespace metadata: name: my-etcd --- apiVersion: operators.coreos.com/v1 kind: OperatorGroup metadata: name: operatorgroup namespace: my-etcd spec: targetNamespaces: - my-etcd --- apiVersion: operators.coreos.com/v1alpha1 kind: Subscription metadata: name: my-etcd namespace: my-etcd spec: channel: singlenamespace-alpha name: etcd source: operatorhubio-catalog sourceNamespace: olm
Edit this file to change the
sourceNamespace
fromolm
tooperator-lifecycle-manager
in theSubscription
section so that it works properly with Operator Lifecycle Manager. Operator Lifecycle Manager runs in theoperator-lifecycle-manager
namespace, which is different to the upstream namespace.--- apiVersion: operators.coreos.com/v1alpha1 kind: Subscription metadata: name: my-etcd namespace: my-etcd spec: channel: singlenamespace-alpha name: etcd source: operatorhubio-catalog sourceNamespace: operator-lifecycle-manager
-
Use the
kubectl apply
command to deploy theetcd
operator.kubectl apply -f etcd.yaml namespace/my-etcd created operatorgroup.operators.coreos.com/operatorgroup created subscription.operators.coreos.com/my-etcd created
The operator is deployed into the namespace set in the operator manifest file, which in this example is
my-etcd
. -
You can see the operator's
ClusterServiceVersion
information using:kubectl get csv -n my-etcd NAME DISPLAY VERSION REPLACES PHASE etcdoperator.v0.9.4 etcd 0.9.4 etcdoperator.v0.9.2 Succeeded
-
You can see the operator pods are running using:
kubectl get pods -n my-etcd NAME READY STATUS RESTARTS AGE etcd-operator-75fb7df8b5-42k7b 3/3 Running 0 5m45s
Removing Operators
To remove an operator and uninstall it, delete the Kubernetes
resources. For example, on a control plane node, use the
kubectl delete
command to delete the operator:
kubectl delete -f etcd.yaml namespace "my-etcd" deleted operatorgroup.operators.coreos.com "operatorgroup" deleted subscription.operators.coreos.com "my-etcd" deleted
Uninstalling the Operator Lifecycle Manager Module
To uninstall the Operator Lifecycle Manager module, uninstall the
module using the olcnectl module uninstall
command. For example:
olcnectl module uninstall \ --environment-name myenvironment \ --name myolm
You can also uninstall the Helm module if you no longer require it.
olcnectl module uninstall \ --environment-name myenvironment \ --name myhelm