Chapter 2. Image Registry Operator in OpenShift Container Platform
2.1. Image Registry on cloud platforms and OpenStack
The Image Registry Operator installs a single instance of the OpenShift Container Platform registry, and manages all registry configuration, including setting up registry storage.
Storage is only automatically configured when you install an installer-provisioned infrastructure cluster on AWS, GCP, Azure, or OpenStack.
After the control plane deploys, the Operator will create a default configs.imageregistry.operator.openshift.io resource instance based on configuration detected in the cluster.
If insufficient information is available to define a complete configs.imageregistry.operator.openshift.io resource, the incomplete resource will be defined and the Operator will update the resource status with information about what is missing.
The Image Registry Operator runs in the openshift-image-registry namespace, and manages the registry instance in that location as well. All configuration and workload resources for the registry reside in that namespace.
The Image Registry Operator’s behavior for managing the pruner is orthogonal to the managementState specified on the ClusterOperator object for the Image Registry Operator. If the Image Registry Operator is not in the Managed state, the image pruner can still be configured and managed by the Pruning custom resource.
However, the managementState of the Image Registry Operator alters the behavior of the deployed image pruner job:
-
Managed: the--prune-registryflag for the image pruner is set totrue. -
Removed: the--prune-registryflag for the image pruner is set tofalse, meaning it only prunes image metatdata in etcd. -
Unmanaged: the--prune-registryflag for the image pruner is set tofalse.
2.2. Image Registry on bare metal and vSphere
2.2.1. Image registry removed during installation
On platforms that do not provide shareable object storage, the OpenShift Image Registry Operator bootstraps itself as Removed. This allows openshift-installer to complete installations on these platform types.
After installation, you must edit the Image Registry Operator configuration to switch the managementState from Removed to Managed.
The Prometheus console provides an ImageRegistryRemoved alert, for example:
"Image Registry has been removed. ImageStreamTags, BuildConfigs and DeploymentConfigs which reference ImageStreamTags may not work as expected. Please configure storage and update the config to Managed state by editing configs.imageregistry.operator.openshift.io."
2.3. Image Registry Operator configuration parameters
The configs.imageregistry.operator.openshift.io resource offers the following configuration parameters.
| Parameter | Description |
|---|---|
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Sets |
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| Value needed by the registry to secure uploads, generated by default. |
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| Defines the Proxy to be used when calling master API and upstream registries. |
|
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| Indicates whether the registry instance should reject attempts to push new images or delete existing ones. |
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| API Request Limit details. Controls how many parallel requests a given registry instance will handle before queuing additional requests. |
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| Determines whether or not an external route is defined using the default hostname. If enabled, the route uses re-encrypt encryption. Defaults to false. |
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| Array of additional routes to create. You provide the hostname and certificate for the route. |
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| Replica count for the registry. |
2.4. Enable the Image Registry default route with the Custom Resource Definition
In OpenShift Container Platform, the Registry Operator controls the registry feature. The Operator is defined by the configs.imageregistry.operator.openshift.io Custom Resource Definition (CRD).
If you need to automatically enable the Image Registry default route, patch the Image Registry Operator CRD.
Procedure
Patch the Image Registry Operator CRD:
$ oc patch configs.imageregistry.operator.openshift.io/cluster --type merge -p '{"spec":{"defaultRoute":true}}'
2.5. Configuring additional trust stores for image registry access
The image.config.openshift.io/cluster custom resource can contain a reference to a config map that contains additional certificate authorities to be trusted during image registry access.
Prerequisites
- The certificate authorities (CA) must be PEM-encoded.
Procedure
You can create a config map in the openshift-config namespace and use its name in AdditionalTrustedCA in the image.config.openshift.io custom resource to provide additional CAs that should be trusted when contacting external registries.
The config map key is the host name of a registry with the port for which this CA is to be trusted, and the base64-encoded certificate is the value, for each additional registry CA to trust.
Image registry CA config map example
apiVersion: v1
kind: ConfigMap
metadata:
name: my-registry-ca
data:
registry.example.com: |
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----
registry-with-port.example.com..5000: | 1
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----
- 1
- If the registry has the port, such as
registry-with-port.example.com:5000,:should be replaced with...
You can configure additional CAs with the following procedure.
To configure an additional CA:
$ oc create configmap registry-config --from-file=<external_registry_address>=ca.crt -n openshift-config
$ oc edit image.config.openshift.io cluster
spec: additionalTrustedCA: name: registry-config
2.6. Configuring storage credentials for the Image Registry Operator
In addition to the configs.imageregistry.operator.openshift.io and ConfigMap resources, storage credential configuration is provided to the Operator by a separate secret resource located within the openshift-image-registry namespace.
The image-registry-private-configuration-user secret provides credentials needed for storage access and management. It overrides the default credentials used by the Operator, if default credentials were found.
Procedure
Create an OpenShift Container Platform secret that contains the required keys.
$ oc create secret generic image-registry-private-configuration-user --from-file=KEY1=value1 --from-literal=KEY2=value2 --namespace openshift-image-registry
