Operator Lifecycle Manager (OLM) helps users install, update, and manage the lifecycle of Kubernetes native applications (Operators) and their associated services running across their OKD clusters. It is part of the Operator Framework, an open source toolkit designed to manage Operators in an effective, automated, and scalable way.
OLM runs by default in OKD 4, which aids cluster administrators in installing, upgrading, and granting access to Operators running on their cluster. The OKD web console provides management screens for cluster administrators to install Operators, as well as grant specific projects access to use the catalog of Operators available on the cluster.
For developers, a self-service experience allows provisioning and configuring instances of databases, monitoring, and big data services without having to be subject matter experts, because the Operator has that knowledge baked into it.
The following custom resource definitions (CRDs) are defined and managed by Operator Lifecycle Manager (OLM):
Application metadata. For example: name, version, icon, required resources.
A repository of CSVs, CRDs, and packages that define an application.
Keeps CSVs up to date by tracking a channel in a package.
Calculated list of resources to be created to automatically install or upgrade a CSV.
Configures all Operators deployed in the same namespace as the
A cluster service version (CSV) represents a specific version of a running Operator on an OKD cluster. It is a YAML manifest created from Operator metadata that assists Operator Lifecycle Manager (OLM) in running the Operator in the cluster.
OLM requires this metadata about an Operator to ensure that it can be kept running safely on a cluster, and to provide information about how updates should be applied as new versions of the Operator are published. This is similar to packaging software for a traditional operating system; think of the packaging step for OLM as the stage at which you make your
A CSV includes the metadata that accompanies an Operator container image, used to populate user interfaces with information such as its name, version, description, labels, repository link, and logo.
A CSV is also a source of technical information required to run the Operator, such as which custom resources (CRs) it manages or depends on, RBAC rules, cluster requirements, and install strategies. This information tells OLM how to create required resources and set up the Operator as a deployment.
A catalog source represents a store of metadata that OLM can query to discover and install Operators and their dependencies. The spec of a
CatalogSource object indicates how to construct a pod or how to communicate with a service that serves the Operator Registry gRPC API.
There are three primary
sourceTypes for a
grpc with an
image reference: OLM pulls the image and runs the pod, which is expected to serve a compliant API.
grpc with an
address field: OLM attempts to contact the gRPC API at the given address. This should not be used in most cases.
configmap: OLM parses the ConfigMap data and runs a pod that can serve the gRPC API over it.
The following example defines a catalog source for OperatorHub.io content:
apiVersion: operators.coreos.com/v1alpha1 kind: CatalogSource metadata: name: operatorhubio-catalog namespace: olm spec: sourceType: grpc image: quay.io/operatorhubio/catalog:latest (1) priority: -400 displayName: Community Operators publisher: OperatorHub.io updateStrategy: registryPoll: (2) interval: 30m
|1||Specify catalog image.|
|2||Automatically check for new versions at a given interval to keep up to date.|
name of the
CatalogSource object is used as input to a subscription, which instructs OLM where to look to find a requested Operator:
Subscriptionobject referencing a catalog source
apiVersion: operators.coreos.com/v1alpha1 kind: Subscription metadata: name: my-operator namespace: olm spec: channel: stable name: my-operator source: operatorhubio-catalog
A subscription, defined by a
Subscription object, represents an intention to install an Operator. It is the custom resource that relates an Operator to a catalog source.
Subscriptions describe which channel of an Operator package to subscribe to, and whether to perform updates automatically or manually. If set to automatic, the subscription ensures Operator Lifecycle Manager (OLM) manages and upgrades the Operator to ensure that the latest version is always running in the cluster.
apiVersion: operators.coreos.com/v1alpha1 kind: Subscription metadata: name: my-operator namespace: operators spec: channel: stable name: my-operator source: my-catalog sourceNamespace: operators
Subscription object defines the name and namespace of the Operator, as well as the catalog from which the Operator data can be found. The channel, such as
stable, helps determine which Operator stream should be installed from the catalog source.
In addition to being easily visible from the OKD web console, it is possible to identify when there is a newer version of an Operator available by inspecting the status of the related subscription. The value associated with the
currentCSV field is the newest version that is known to OLM, and
installedCSV is the version that is installed on the cluster.
An install plan, defined by an
InstallPlan object, describes a set of resources to be created to install or upgrade to a specific version of an Operator, as defined by a cluster service version (CSV).
An Operator group, defined by the
OperatorGroup resource, provides multitenant configuration to OLM-installed Operators. An Operator group selects target namespaces in which to generate required RBAC access for its member Operators.
The set of target namespaces is provided by a comma-delimited string stored in the
olm.targetNamespaces annotation of a cluster service version (CSV). This annotation is applied to the CSV instances of member Operators and is projected into their deployments.
For more information, see the Operator groups guide.