CR provides the registry replication feature for Standard Edition instances. You can create custom registry replication rules to synchronize images and Helm charts from the specified source instance to a specific location in the target instance.

Application scenario

This topic covers the following two registry replication scenarios:

Replication scenario	Description
Same-region or cross-region replication‌	Replicate images from a Standard Edition instance to other Standard Edition instances in the same region or across regions under the same Volcano Engine root account. This applies to scenarios such as multi-region deployment, disaster recovery and backup, and image pulls from nearby locations.
Synchronize to a custom repository	Synchronize images in the Standard Edition Instance to external repositories outside Volcano Engine (such as Self-built Harbor, Alibaba Cloud ACR, Huawei Cloud SWR, Tencent Cloud TCR, and more). This applies to scenarios such as hybrid cloud deployment, cross-cloud distribution, and multi-cloud disaster recovery.

Prerequisites

Application scenario	Condition
Same-region or cross-region replication‌	Both the source and destination instances are Standard Edition instances and are in the Running state. For information about how to create an instance, see Creating Standard instances.
		The source and destination instances belong to the same Volcano Engine root account.
		A destination Standard Edition instance has been purchased, and a namespace has been created. For information about how to create a namespace, see Creating namespaces.
		For cross-region replication, Public network access must be enabled separately for the source and destination instances. For information about how to enable public network access, see Enabling public network access.
Synchronize to a custom repository	The source instance is a Standard Edition instance and is in the Running state. For information about how to create an instance, see Creating Standard instances.
		Supported external destination repository types for replication: self-managed Harbor instances, as well as repositories from Alibaba Cloud, Huawei Cloud, and Tencent Cloud.
		Custom repositories support connections over the public network.
		The service address, username, and password of the external destination repository have been obtained.
		It has been confirmed that the corresponding namespace exists in the external destination repository. Replication fails if no namespace with the same name exists.

Procedure

Step 1: Configure a registry replication rule

Log in to the CR console.

In the left navigation pane, select Registry replication, and click Create registry replication rule.

On the Create registry replication rule page, configure the parameters based on your needs.

Registry replication type

Parameter	Description
Synchronization type	Select Inter-instance synchronization to replicate from a Standard Edition instance to other Standard Edition instances under the same account or to an external custom repository.

Basic information

Parameter	Description
Name	The custom name of the registry replication rule. The name must be unique within the same account.
Description	Enter a description for the rule. The description can be empty and cannot exceed 200 characters.

Source instance

Parameter	Description
Instance	Select the source Standard Edition instance to be replicated.
Namespace	Select the name of the namespace to be synchronized in the source instance.
Repository	The names of the OCI artifact repositories to be synchronized. All: Synchronize all OCI artifact repositories in the specified namespace. Regular expression matching: Matches the OCI artifact repositories to be replicated by using a regular expression. For common regex matching examples, see Regular expression matching examples.
Tag	The OCI artifact tags to be synchronized. All: Synchronize all OCI artifact tags in the specified repository. Regular expression matching: Matches the OCI artifact versions to be replicated by using a regular expression. For common regex matching examples, see Regular expression matching examples.

Target instance

Within the root account (same-region or cross-region replication)

Custom (replication to a custom repository)

Replicate images to other Standard Edition instances under the same account, either within the same region or across regions.

Parameter	Description
Synchronization type	Select Within the main account.
Region	warning For cross-region replication, Public network access must be enabled for both the source and destination instances. For information about how to enable public network access, see Enabling public network access. Select the region where the target Standard Edition instance is located.
Instance name	Select the target Standard Edition instance.
Namespace	Select the namespace in the target instance. If you do not configure this parameter, replication defaults to a namespace with the same name as the source instance. If no namespace with that name exists, one is automatically created.

Synchronization rules

Parameter	Description
Image overwriting	You can select "Enable" to enable this feature. After enabling, if the target side has images with the same name as those on the source side, the source-side images will overwrite the existing images with the same name on the target side.
Rule state	Select this option to enable the rule and configure the following trigger conditions: Event-driven triggering: Synchronization is automatically triggered when a rule-compliant event occurs. That is, if you push a rule-compliant artifact to the OCI artifact repository that complies with the registry replication rule in the source instance, synchronization will be automatically triggered once, and only the newly pushed artifact will be synchronized. You can also set Trigger immediately to Yes to specify that rule matching is triggered immediately after the registry replication rule is created to perform a synchronization operation. Timed trigger: Synchronization is triggered at the configured fixed intervals, with the first synchronization time set by the user. First trigger time: Take note that this parameter can only be set to any time starting from the current time. Trigger frequency: Specify the synchronization interval. By default, synchronization is triggered every 24 hours. The valid interval ranges from 1 to 720 hours. Manual trigger: If this option is selected, the rule will not be triggered automatically and synchronization must be executed manually.

Step 2: Execute the registry replication rule

The following three trigger methods are supported:

If you select Event-driven triggering when you configure the registry replication rule, the system automatically triggers synchronization when a rule-compliant event occurs. If you select Event-driven triggering and set Trigger immediately to Yes, rule matching will be triggered immediately after the registry replication rule is created.

If you select Timed trigger when you configure the registry replication rule, the system will automatically trigger synchronization at scheduled intervals.

If Manual trigger is selected, you can manually trigger the rule by referring to the following steps:

In the left navigation pane of the CR console, select Registry replication.

On the Registry replication page, locate the rule to be triggered, and click Trigger in the Actions column.

In the system pop-up dialog box, verify the rule information, and click Confirm to trigger the synchronization operation.

Step 3: View synchronization logs

In the left navigation pane of the CR console, select Registry replication.

On the Registry replication page, locate the target rule and click the rule name.

On the rule details page, click the Synchronization log tab to view all synchronization logs of the rule.

Parameter	Description
Task ID	The synchronization task ID (unique within the instance).
Synchronization state	The task state, which can be Running, Succeed, and Failed. tip If the synchronization state is Succeed, the synchronization task is triggered as expected and at least one image tag is synchronized. If the synchronization state is Failed, the task fails to be triggered. Possible causes: The source Standard Edition instance is not in the Running state. The destination Standard Edition instance is not in the Running state.
Task duration	The time consumed to complete all synchronization tasks.
Success rate	(Number of synchronized tags/Total number of tags to be synchronized) × 100%
Number of synchronization repositories	The number of OCI artifact repositories to be synchronized by the current task.
Trigger time	The trigger time of the synchronization task.

Click the task ID to view the details of the synchronization task. The following information is displayed: [namespace]/[repo]:tag of the source instance, [namespace]/[repo]:tag of the target instance, and synchronization state of the synchronization task.

If the synchronization state is Succeed, the artifacts have been successfully synchronized from the source instance to the target instance. If the synchronization state is Failed, the artifacts fail to be synchronized from the source instance to the target instance.

Parameter	Description
Synchronization type	Select Custom.
Service address	The external custom repository address starting with http(s)://. For example, http(s)://index.dockerhub.io.
Ignore certificate validity	Whether to ignore certificate validity. Yes: Ignores the validity of the external repository certificate and proceeds with replication. No: Verifies certificate validity. Replication cannot proceed if the certificate is outside its validity period. External repository certificates must be issued by an authoritative institution.
Username	The username for logging in to the external custom repository.
Password	The password for logging in to the external custom repository.
Namespace	warning If the external custom repository is Alibaba Cloud ACR, do not include the / character in repository (repo) names within a namespace. Otherwise, replication will fail. Enter the target namespace name in the external custom repository. If you do not configure this parameter, replication defaults to a namespace with the same name as the source instance. If no namespace with that name exists, replication fails.

Container Registry