Azure Service Fabric node types and virtual machine scale sets

Virtual machine scale sets are an Azure compute resource. You can use scale sets to deploy and manage a collection of virtual machines as a set. Each node type that you define in an Azure Service Fabric cluster sets up exactly one scale set: multiple node types cannot be backed by the same scale set and one node type should not be backed by multiple scale sets.

The Service Fabric runtime is installed on each virtual machine in the scale set by the Microsoft.Azure.ServiceFabric Virtual Machine extension. You can independently scale each node type up or down, change the OS SKU running on each cluster node, have different sets of ports open, and use different capacity metrics.

The following figure shows a cluster that has two node types, named FrontEnd and BackEnd. Each node type has five nodes.

Map virtual machine scale set instances to nodes

As shown in the preceding figure, scale set instances start at instance 0, and then increase by 1. The numbering is reflected in the node names. For example, node BackEnd_0 is instance 0 of the BackEnd scale set. This particular scale set has five instances, named BackEnd_0, BackEnd_1, BackEnd_2, BackEnd_3, and BackEnd_4.

When you scale out a scale set, a new instance is created. The new scale set instance name typically is the scale set name plus the next instance number. In our example, it is BackEnd_5.

Map scale set load balancers to node types and scale sets

If you deployed your cluster in the Azure portal or used the sample Azure Resource Manager template, all resources under a resource group are listed. You can see the load balancers for each scale set or node type. The load balancer name uses the following format: LB-<node type name>. An example is LB-sfcluster4doc-0, as shown in the following figure:

Service Fabric Virtual Machine Extension

Service Fabric Virtual Machine Extension is used to bootstrap Service Fabric to Azure Virtual Machines, and configure the Node Security.

The following is a snippet of Service Fabric Virtual Machine extension:

"extensions": [
  {
    "name": "[concat('ServiceFabricNodeVmExt','_vmNodeType0Name')]",
    "properties": {
      "type": "ServiceFabricLinuxNode",
      "autoUpgradeMinorVersion": true,
      "enableAutomaticUpgrade": true,
      "protectedSettings": {
        "StorageAccountKey1": "[listKeys(resourceId('Microsoft.Storage/storageAccounts', variables('supportLogStorageAccountName')),'2015-05-01-preview').key1]",
       },
       "publisher": "Microsoft.Azure.ServiceFabric",
       "settings": {
         "clusterEndpoint": "[reference(parameters('clusterName')).clusterEndpoint]",
         "nodeTypeRef": "[variables('vmNodeType0Name')]",
         "durabilityLevel": "Silver",
         "enableParallelJobs": true,
         "nicPrefixOverride": "[variables('subnet0Prefix')]",
         "dataPath": "D:\\\\SvcFab",
         "certificate": {
           "commonNames": [
             "[parameters('certificateCommonName')]"
           ],
           "x509StoreName": "[parameters('certificateStoreValue')]"
         }
       },
       "typeHandlerVersion": "2.0"
     }
   },

The following are the property descriptions:

Name	Allowed Values	Guidance or Short Description
name	string	Unique name for extension
type	"ServiceFabricLinuxNode" or "ServiceFabricNode"	Identifies OS Service Fabric is bootstrapping to
autoUpgradeMinorVersion	true or false	Use newest minor version of extension at deployment time
enableAutomaticUpgrade	true or false	Automatically upgrade extension once a non-major version is available. Only available for type ServiceFabricLinuxNode
publisher	Microsoft.Azure.ServiceFabric	Name of the Service Fabric extension publisher
clusterEndpoint	string	URI:PORT to Management endpoint
nodeTypeRef	string	Name of nodeType
durabilityLevel	bronze, silver, gold, platinum	Time allowed to pause immutable Azure Infrastructure
enableParallelJobs	true or false	Enable Compute ParallelJobs like remove VM and reboot VM in the same scale set in parallel
nicPrefixOverride	string	Subnet Prefix like "10.0.0.0/24"
commonNames	string[]	Common Names of installed cluster certificates
x509StoreName	string	Name of Store where installed cluster certificate is located
typeHandlerVersion	1.1	Version of Extension. 1.0 classic versions of extension are recommended to upgrade to 1.1
dataPath	string	Path to the drive used to save state for Service Fabric system services and application data.

Next steps

• See the overview of the "Deploy anywhere" feature and a comparison with Azure-managed clusters.
• Learn about cluster security.
• Remote connect to a specific scale set instance
• Update the RDP port range values on cluster VMs after deployment
• Change the admin username and password for cluster VMs