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Geo-replicate container images#

Reliability · Container Registry · Rule · 2020_12

Use geo-replicated container registries to compliment a multi-region container deployments.

Description#

A container registry is stored and maintained by default in a single region. Optionally geo-replication to one or more additional regions can be enabled.

Geo-replicating container registries provides the following benefits:

  • Single registry/ image/ tag names can be used across multiple regions.
  • Network-close registry access within the region reduces latency.
  • As images are pulled from a local replicated registry, each pull does not incur additional egress costs.

Recommendation#

Consider using a geo-replicated container registry for multi-region deployments.

Examples#

Configure with Azure template#

To enable geo-replication for Container Registries that pass this rule:

  • Set sku.name to Premium (required for geo-replication).
  • Add replications child resource with location set to the region to replicate to.

For example:

Azure Template snippet
{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "metadata": {
    "_generator": {
      "name": "bicep",
      "version": "0.5.6.12127",
      "templateHash": "12610175857982700190"
    }
  },
  "parameters": {
    "acrName": {
      "type": "string",
      "defaultValue": "[format('acr{0}', uniqueString(resourceGroup().id))]",
      "maxLength": 50,
      "minLength": 5,
      "metadata": {
        "description": "Globally unique name of your Azure Container Registry"
      }
    },
    "acrAdminUserEnabled": {
      "type": "bool",
      "defaultValue": false,
      "metadata": {
        "description": "Enable admin user that has push / pull permission to the registry."
      }
    },
    "location": {
      "type": "string",
      "defaultValue": "[resourceGroup().location]",
      "metadata": {
        "description": "Location for registry home replica."
      }
    },
    "acrSku": {
      "type": "string",
      "defaultValue": "Premium",
      "allowedValues": [
        "Premium"
      ],
      "metadata": {
        "description": "Tier of your Azure Container Registry. Geo-replication requires Premium SKU."
      }
    },
    "acrReplicaLocation": {
      "type": "string",
      "metadata": {
        "description": "Short name for registry replica location."
      }
    }
  },
  "resources": [
    {
      "type": "Microsoft.ContainerRegistry/registries",
      "apiVersion": "2019-12-01-preview",
      "name": "[parameters('acrName')]",
      "location": "[parameters('location')]",
      "sku": {
        "name": "[parameters('acrSku')]"
      },
      "tags": {
        "displayName": "Container Registry",
        "container.registry": "[parameters('acrName')]"
      },
      "properties": {
        "adminUserEnabled": "[parameters('acrAdminUserEnabled')]"
      }
    },
    {
      "type": "Microsoft.ContainerRegistry/registries/replications",
      "apiVersion": "2019-12-01-preview",
      "name": "[format('{0}/{1}', parameters('acrName'), parameters('acrReplicaLocation'))]",
      "location": "[parameters('acrReplicaLocation')]",
      "properties": {},
      "dependsOn": [
        "[resourceId('Microsoft.ContainerRegistry/registries', parameters('acrName'))]"
      ]
    }
  ],
  "outputs": {
    "acrLoginServer": {
      "type": "string",
      "value": "[reference(resourceId('Microsoft.ContainerRegistry/registries', parameters('acrName'))).loginServer]"
    }
  }
}

Configure with Bicep#

To deploy Container Registries that pass this rule:

  • Set sku.name to Premium (required for geo-replication).
  • Add replications child resource with location set to the region to replicate to.

For example:

Azure Bicep snippet
resource containerRegistry 'Microsoft.ContainerRegistry/registries@2019-12-01-preview' = {
  name: acrName
  location: location
  sku: {
    name: 'Premium'
  }
  tags: {
    displayName: 'Container Registry'
    'container.registry': acrName
  }
  properties: {
    adminUserEnabled: acrAdminUserEnabled
  }
}

resource containerRegistryReplica 'Microsoft.ContainerRegistry/registries/replications@2019-12-01-preview' = {
  parent: containerRegistry
  name: '${acrReplicaLocation}'
  location: acrReplicaLocation
  properties: {
  }
}

Notes#

This rule applies when analyzing resources deployed (in-flight) to Azure.

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