Azure Classroom Series – 14/Feb/2021

Azure Resource Manager Templates

• These are JSON files that define the infrastructure and configuration of your application.
• These templates can be reused to create the same application cofiguration in different
  • resource groups
  • subscriptions
• Consider the scenario where you need to deploy the following architecture into various environments (DEV, QA, STAGING, PRODUCTION)
• To solve this we need some kind of automation,
  • One approach will be to write a script using Azure CLI / Azure Powershell. The problem with this approach changing the script for any updates in architectures and changing values for resources like vm size, zone etc will be difficult to handle
  • Second approach is to create a template that defines the above architecture in json format and execute it on various environments.
• ARM Templates provide us the following advantages
  • declarative syntax
  • Repeatable results
  • Orchestration
  • Modular files
  • Preview changes
  • Tracked deployments
• Exercise:
  • Create one linux vm in a new resource group
  • After linux vm is created, add one windows vm to the same resource group
  • Now navigate to the resource group section and select the created resource group
• Azure is creating a template when we try to create resources.
• In this section we will learn how to create an arm template,
• To do this lets setup our developer environment
  • Ensure Azure CLI or Azure Powershell is installed on your machine Refer Here
  • Ensure Visual studio code is installed

How are resources created in Azure

• In your subscription, you will have resource providers
• Resource Provider in azure is capable of creating resources which it provides or offers
• When we try to create any resource in Azure (from portal/cli/arm template)
  • It will check if the resource provider is registered or not
  • If the resource provider is not registered then it will throw error messages
  • If the resource provide is register then it will validate the values passed and if they are ok resources will be created.

ARM Template file

• ARM Template has 5 sections
  • Parameters
  • Variables
  • User-defined functions
  • Resources
  • Outputs
• The template format Refer Here

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "",
  "apiProfile": "",
  "parameters": {  },
  "variables": {  },
  "functions": [  ],
  "resources": [  ],
  "outputs": {  }
}

• So the minimal arm template will be

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "",
  "resources": [  ]
}

• Now lets try to understand how to fill these sections
• For filling Schema section: We need to understand what is the deployment level
  • Resource Group: "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#"
  • Subscription: "https://schema.management.azure.com/schemas/2018-05-01/subscriptionDeploymentTemplate.json#"
  • Tenant Level: "https://schema.management.azure.com/schemas/2019-08-01/tenantDeploymentTemplate.json#"
  • Management Group: "https://schema.management.azure.com/schemas/2019-08-01/managementGroupDeploymentTemplate.json#"
• Content version: version of your template
• resources: This specifies what you want to create. Now lets try to create a storage account
  • manual steps:
    • Create a resource group
    • Create a storage account
• Lets try to write a arm template to do the same thing, lets start by filling $schema, contentVersion. Refer Here for the changes
• Now we need to add the resource storage account
• Navigate to the page Refer Here
• Refer Here to this changeset to fill to storage account information
• Further reading
  • Refer Here
  • Refer Here
• Next Steps:
  • Lets try to execute the template and see the results
  • Lets explore more options