Tutorial: Scale an application running in Service Fabric Mesh

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Important

The preview of Azure Service Fabric Mesh has been retired. New deployments will no longer be permitted through the Service Fabric Mesh API. Support for existing deployments will continue through April 28, 2021.

For details, see Azure Service Fabric Mesh Preview Retirement.

This tutorial is part two of a series. Learn how to manually scale the number service instances of an application that was previously deployed to Service Fabric Mesh. When you're finished, you'll have a front-end service running three instances and a data service running two instances.

In part two of the series, you learn how to:

  • Configure the desired number of service instances
  • Perform an upgrade

In this tutorial series you learn how to:

Service Fabric Mesh is currently in preview. Previews are made available to you on the condition that you agree to the supplemental terms of use. Some aspects of this feature may change prior to general availability (GA).

Prerequisites

Before you begin this tutorial:

Manually scale your services in or out

One of the main advantages of deploying applications to Service Fabric Mesh is the ability for you to easily scale your services in or out. This should be used for handling varying amounts of load on your services, or improving availability.

This tutorial uses the To Do List sample as an example, which was deployed previously and should now be running. The application has two services: WebFrontEnd and ToDoService. Each service was initially deployed with a replica count of 1. To view the number of running replicas for the WebFrontEnd service, run the following:

az mesh service show --resource-group myResourceGroup --name WebFrontEnd --app-name todolistapp --query "replicaCount"

To view the number of running replicas for the ToDoService service, run the following:

az mesh service show --resource-group myResourceGroup --name ToDoService --app-name todolistapp --query "replicaCount"

In the deployment template for the application resource, each service has a replicaCount property that can be used to set the number of times you want that service deployed. An application can consist of multiple services, each service with a unique replicaCount number, which are deployed and managed together. In order to scale the number of service replicas, modify the replicaCount value for each service you want to scale in the deployment template or parameters file. Then upgrade the application.

Modify the deployment template parameters

When you have values in your template that you anticipate changing once the application is deployed, or would like to have the option to change on a per deployment basis (if you plan on reusing this template for other deployments), the best practice is to parameterize the values.

Previously, the application was deployed using the mesh_rp.windows.json deployment template and mesh_rp.windows.parameter.json parameters files.

Open the mesh_rp.windows.parameter.json parameters file locally and set the frontEndReplicaCount value to 3 and the serviceReplicaCount value to 2:

      "frontEndReplicaCount":{
        "value": "3"
      },
      "serviceReplicaCount":{
        "value": "2"
      }

Save your changes to the parameters file. The frontEndReplicaCount and serviceReplicaCount parameters are declared in the parameters section of the mesh_rp.windows.json deployment template:

"frontEndReplicaCount":{
      "defaultValue": "1",
      "type": "string"
    },
    "serviceReplicaCount":{
      "defaultValue": "1",
      "type": "string"
    }

The WebFrontEnd service replicaCount property references the frontEndReplicaCount parameter and the ToDoService service replicaCount property references the serviceReplicaCount parameter:

    "services": [
    {
    "name": "WebFrontEnd",
    "properties": {
        "description": "WebFrontEnd description.",
        "osType": "Windows",
        "codePackages": [
        {
            ...
        }
        ],
        "replicaCount": "[parameters('frontEndReplicaCount')]",
        "networkRefs": [
        {
            "name": "[resourceId('Microsoft.ServiceFabricMesh/networks', 'todolistappNetwork')]"
        }
        ]
    }
    },
    {
    "name": "ToDoService",
    "properties": {
        "description": "ToDoService description.",
        "osType": "Windows",
        "codePackages": [
        {
            ...
        }
        ],
        "replicaCount": "[parameters('serviceReplicaCount')]",
        "networkRefs": [
        {
            "name": "[resourceId('Microsoft.ServiceFabricMesh/networks', 'todolistappNetwork')]"
        }
        ]
    }
    }
],

Once your template has been modified, upgrade your application.

Upgrade your application

While the application is running, you can upgrade it by redeploying the template and updated parameters file:

az mesh deployment create --resource-group myResourceGroup --template-file c:\temp\mesh_rp.windows.json --parameters c:\temp\mesh_rp.windows.parameters.json

This will start a rolling upgrade to your application and you should see the services instances increase in a few minutes. To view the number of running replicas for the WebFrontEnd service, run the following:

az mesh service show --resource-group myResourceGroup --name WebFrontEnd --app-name todolistapp --query "replicaCount"

To view the number of running replicas for the ToDoService service, run the following:

az mesh service show --resource-group myResourceGroup --name ToDoService --app-name todolistapp --query "replicaCount"

Next steps

In this part of the tutorial, you learned how to:

  • Configure the desired number of service instances
  • Perform an upgrade

Advance to the next tutorial:

Upgrade an application running in Service Fabric Mesh