Sample to start / stop VMs on a schedule

Create an Azure function application and deploy functions that starts or stops virtual machines in the specified resource group, subscription, or by tag on a schedule.

Prerequisites

Before running this sample, you must have the following:

• Install Azure Core Tools version 2.x

• Install the Azure CLI

Create a new resource group and function application on Azure

Run the following PowerShell command and specify the value for the function application name in the TemplateParameterObject hashtable.

New-AzResourceGroup -Name <resource group name> -Location <location>

New-AzResourceGroupDeployment -ResourceGroupName <resource group name> -TemplateParameterObject @{"functionAppName" = "<your function app name>"} -TemplateUri "https://raw.githubusercontent.com/Azure/azure-quickstart-templates/master/101-functions-managed-identity/azuredeploy.json" -verbose

This should create a new resource group with a function application and a managed service identity enabled. The id of the service principal for the MSI should be returned as an output from the deployment.

Example: principalId String cac1fa06-2ad8-437d-99f6-b75edaae2921

Grant the managed service identity contributor access to the subscription or resource group so it can perform actions

The below command sets the access at the subscription level.

$Context = Get-AzContext
New-AzRoleAssignment -ObjectId <principalId> -RoleDefinitionName Contributor -Scope "/subscriptions/$($Context.Subscription)"

Clone repository or download files to local machine

• Download the repository files or clone to local machine.

• Change to the PowerShell/StartStopVMOnTimer directory.

Get the local.settings.json values from the function application created in Azure

func azure functionapp fetch-app-settings <function app name>

This should create a local.settings.json file in the StartStopVMOnTimer directory beside the host.json with the settings from the Azure function app.

Test the functions locally

Start the function with the following command

func start

You can then call a trigger function by performing a post against the function on the admin api. Open up another Powershell console session and run:

Invoke-RestMethod "http://localhost:7071/admin/functions/StartVMOnTimer" -Method post -Body '{}' -ContentType "application/json"

Modify the values for each of the below variables in run.ps1 as needed.

# Specify the VMs that you want to stop. Modify or comment out below based on which VMs to check.
$VMResourceGroupName = "Contoso"
#$VMName = "ContosoVM1"
#$TagName = "AutomaticallyStart"

Modify the start and stop time in the function.json file. They are currently set to 8am and 8pm UTC. You can change the timezone by modifying the application setting WEBSITE_TIME_ZONE. You can also pass in a parameter 'timezone' to the above ARM template that was used to create the function application if you want a different timezone so that daylight savings time will be honored.

{
  "disabled": false,
  "bindings": [
    {
      "name": "Timer",
      "type": "timerTrigger",
      "direction": "in",
      "schedule": "0 0 20 * * *"
    }
  ]
}

Publish the functions to the function application in Azure

func azure functionapp publish <function app name>