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Use Bicep to create an experiment in Azure Chaos Studio

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Bicep is a domain-specific language (DSL) that uses declarative syntax to deploy Azure resources. It provides concise syntax, reliable type safety, and support for code reuse. Bicep offers the best authoring experience for your infrastructure-as-code solutions in Azure.

This article includes a sample Bicep file to get started in Azure Chaos Studio, including:

  • Onboarding a resource as a target (for example, a Virtual Machine)
  • Enabling capabilities on the target (for example, Virtual Machine Shutdown)
  • Creating a Chaos Studio experiment
  • Assigning the necessary permissions for the experiment to execute

Build a Virtual Machine Shutdown experiment

In this sample, we create a chaos experiment with a single target resource and a single virtual machine shutdown fault. You can modify the experiment by referencing the fault library and recommended role assignments.

Prerequisites

This sample assumes:

  • The Chaos Studio resource provider is already registered with your Azure subscription
  • You already have a resource group in a region supported by Chaos Studio
  • A virtual machine is deployed in the resource group

Review the Bicep file

@description('The existing virtual machine resource you want to target in this experiment')
param targetName string

@description('Desired name for your Chaos Experiment')
param experimentName string

@description('Desired region for the experiment, targets, and capabilities')
param location string = resourceGroup().location

// Define Chaos Studio experiment steps for a basic Virtual Machine Shutdown experiment
param experimentSteps array = [
  {
    name: 'Step1'
    branches: [
      {
        name: 'Branch1'
        actions: [
          {
            name: 'urn:csci:microsoft:virtualMachine:shutdown/1.0'
            type: 'continuous'
            duration: 'PT10M'
            parameters: [
              {
                key: 'abruptShutdown'
                value: 'true'
              }
            ]
            selectorId: 'Selector1'
          }
        ]
      }
    ]
  }
]

// Reference the existing Virtual Machine resource
resource vm 'Microsoft.Compute/virtualMachines@2023-03-01' existing = {
  name: targetName
}

// Deploy the Chaos Studio target resource to the Virtual Machine
resource chaosTarget 'Microsoft.Chaos/targets@2024-01-01' = {
  name: 'Microsoft-VirtualMachine'
  location: location
  scope: vm
  properties: {}

  // Define the capability -- in this case, VM Shutdown
  resource chaosCapability 'capabilities' = {
    name: 'Shutdown-1.0'
  }
}

// Define the role definition for the Chaos experiment
resource chaosRoleDefinition 'Microsoft.Authorization/roleDefinitions@2022-04-01' existing = {
  scope: vm
  // In this case, Virtual Machine Contributor role -- see https://learn.microsoft.com/azure/role-based-access-control/built-in-roles 
  name: '9980e02c-c2be-4d73-94e8-173b1dc7cf3c'
}

// Define the role assignment for the Chaos experiment
resource chaosRoleAssignment 'Microsoft.Authorization/roleAssignments@2022-04-01' = {
  name: guid(vm.id, chaosExperiment.id, chaosRoleDefinition.id)
  scope: vm
  properties: {
    roleDefinitionId: chaosRoleDefinition.id
    principalId: chaosExperiment.identity.principalId
    principalType: 'ServicePrincipal'
  }
}

// Deploy the Chaos Studio experiment resource
resource chaosExperiment 'Microsoft.Chaos/experiments@2024-01-01' = {
  name: experimentName
  location: location // Doesn't need to be the same as the Targets & Capabilities location
  identity: {
    type: 'SystemAssigned'
  }
  properties: {
    selectors: [
      {
        id: 'Selector1'
        type: 'List'
        targets: [
          {
            id: chaosTarget.id
            type: 'ChaosTarget'
          }
        ]
      }
    ]
    steps: experimentSteps
  }
}

Deploy the Bicep file

  1. Save the Bicep file as chaos-vm-shutdown.bicep to your local computer.

  2. Deploy the Bicep file using either Azure CLI or Azure PowerShell, replacing exampleRG with the existing resource group that includes the virtual machine you want to target.

    az deployment group create --resource-group exampleRG --template-file chaos-vm-shutdown.bicep

  3. When prompted, enter the following values:

    • targetName: the name of an existing Virtual Machine within your resource group that you want to target
    • experimentName: the desired name for your Chaos Experiment

  4. The template should deploy within a few minutes. Once the deployment is complete, navigate to Chaos Studio in the Azure portal, select Experiments, and find the experiment created by the template. Select it, then Start the experiment.

Next steps