There are multiple resources involved in a operator Subscription in a OpenShift 4 cluster. This document explains different blocks of subscribing an operator. Also explains how to include a custom catalog for development or expriement purposes. The resources used in this are based on OpenShift 4.5 and Operator SDK v1.0 versions. This blog assumes that the reader has fair knowledge of operators.

Resources involved in creating and subscribing an custom operator are:

  • Operator Bundles
  • CatalogSource
  • OperatorGroup
  • Subscription
  • ClusterServiceVersion

CatalogSource Contents

This diagram depicts how the operator image (testpmd-operator) and its metadata information is encompassed in to a operator bundle image (testpmd-operator-bundle). Multiple operator bundle images can be sourced from a single catalog index image (nfv-example-cnf-catalog). Using this image, a CatalogSource resource object should be created to source the testpmd-operator.

Operator Bundles

Operator SDK v1.0 by default scaffolds the necessary file structure and make commands to generate the operator bundle images. Operator bundle image consists of the CRDs, CSVs and RBACK definitions of an operator specific to a version.

When the operator is scaffolded for operator sdk v1.0 version, it creates the Makefile with commands to generate the bunlde files and bundle container image. Executing the make commands make bundle and make bundle-build should create the bundle container image for the operator, which need to be pushed to a registry.


CatalogSource is the source for operators and its different versions. When a CatalogSource is created in a cluster, it creates a database consisting of all the operators that this catalog can source. The operator will be exposed as a PackageManifests to know what the operator consists of and its different versions.

The catalog source container image is created using the opm index add command, by providing operator bundle images. A sample command to create a catalog index image using the opm tool is:

opm index add -u podman --bundles \, \

Once the operator catalog index image is created, then create a CatalogSource resource to provide the custom operators in the cluster:

kind: CatalogSource
  name: nfv-example-cnf-catalog
  namespace: openshift-marketplace
  sourceType: grpc
  displayName: NFV Example CNF Catalog
      interval: 30m


An OperatorGroup resource provides the list of namespaces or a selector for namespace on which the RBAC should be generated for its member operators. The target namespace will be applied to all the CSVs which will be installed in this namespace.

kind: OperatorGroup
  name: example-cnf-operator-group
  namespace: example-cnf
    - example-cnf


A Subscription resource initiates an operator installation from the specified catalog source with the specified channel. Once a Subscription is created, then OLM creates a job to fetch the required CRDs, CSVs and RBACs for the specified operator from the catalog source (via the operator bundle image) and installs the CSV to the required namespace.

CatalogSource Contents

Create a Subscription for the testpmd operator from the custom catalog, like:

kind: Subscription
  name: testpmd-operator-subscription
  namespace: example-cnf
  channel: "alpha"
  name: testpmd-operator
  source: nfv-example-cnf-catalog
  sourceNamespace: openshift-marketplace

On creating a subscription, OLM creates a job to process the request and install the required resoures. A snaphot of the job and pods associated with this operation is shown below:

$ oc -n openshift-marketplace get all

NAME                                                                        COMPLETIONS   DURATION   AGE
job.batch/37eae4d05fc938390e8ad0264dd3b703722ad98c1a9f565b585b14d6eed6425   1/1           19s        24h
job.batch/8d971dd002fd5e41e1e17949ff724b5bf52e8cadfe25f09b0887b5f67e24523   1/1           19s        24h

NAME                                                                  READY   STATUS      RESTARTS   AGE
pod/37eae4d05fc938390e8ad0264dd3b703722ad98c1a9f565b585b14d6eef4r6z   0/1     Completed   0          24h
pod/8d971dd002fd5e41e1e17949ff724b5bf52e8cadfe25f09b0887b5f67e2kjv2   0/1     Completed   0          24h
pod/nfv-example-cnf-catalog-z969l                                     1/1     Running     0          14m

The job that is created above gets the CRD and CSV from the operator bundle and then installs both in the cluster. A snapshot of how the CSVs will be installed:

$ oc get crd  | grep 'testpmds\|trex\|NAME'
NAME                                                        CREATED AT                            2020-09-17T11:40:41Z                         2020-09-17T11:40:44Z

$ oc -n example-cnf get csv
NAME                      DISPLAY            VERSION   REPLACES   PHASE
testpmd-operator.v0.1.1   TestPMD Operator   0.1.1                Succeeded
trex-operator.v0.1.1      TRex Operator      0.1.1                Succeeded

The operator deployment will be done by the CSV installation, which will create the deployment resource for the operator associated.


The ClusterServiceVersion resources contains both technical information of the operator and the user interface info like logo, description. The CSV contains the operator deployment resources and the RBAC rules that the operator requires. As part of CSV installtion (which is triggered by the creation of a Subscription), the operator will be deployed.

$ oc -n example-cnf get all
NAME                                                       READY   STATUS    RESTARTS   AGE
pod/testpmd-operator-controller-manager-79fc6f64cb-c6vw8   1/1     Running   0          19h
pod/trex-operator-controller-manager-54db9f5b6d-n62x5      1/1     Running   0          19h

NAME                                                  READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/testpmd-operator-controller-manager   1/1     1            1           19h
deployment.apps/trex-operator-controller-manager      1/1     1            1           19h

NAME                                                             DESIRED   CURRENT   READY   AGE
replicaset.apps/testpmd-operator-controller-manager-79fc6f64cb   1         1         1       19h
replicaset.apps/trex-operator-controller-manager-54db9f5b6d      1         1         1       19h