This URL points to the location of the JSON schema file that explains the version of the template language. The version number will vary according to the scope of the deployment and text editor you are using. If you are using Visual Studio Code with the Azure Resource Manager extension, then the schema will be as follows:
https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#
If you are not using the extension, other text editors including Visual Studio Code will not be able to process this schema. Microsoft recommends using the following for text editors without the Azure Resource Manager extension:
https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#
If you deploy to another scope, like the subscription scope, management scope, or tenant scope, the schema will vary. Luckily, using the ARM extension on VS Code, you will be able to change the schema using code snippets without the need to memorize them. Figure 8.6 shows other code snippets like arm!mg, arm!s, and arm!t. These represent the management group, subscription, and tenant-level code snippets, respectively.
Content Version (contentVersion)
This is used by the end user to identify the version of the ARM template they are using. For example, you can give a value like 1.0.0 to represent that this is the version and then later if you need to make any changes to the template, you can modify the version to say 1.1.0. The content version will help the user to ensure that they are deploying the right version of the template that they authored. If you are saving the template to source control or any repository, the content version will help you find the latest version of your ARM template. It’s not mandatory that you need to update the version numbers unless you are using source control; you can reuse the same version number for multiple deployments.
Parameters (parameters)
Parameters are used to specify the values that are configurable when you execute the template. The following is an example that shows how parameters are mentioned in the parameters section:
“parameters”: {
“resourceLocation”: {
“type”: “string”,
“metadata”: {
“description”: “Location of resource”
}
}
},
In this example, you are specifying a parameter called resourceLocation. Along with that you are adding the type of data that you expect from the user and description for a second person to understand the purpose of the parameter when they read the ARM template. When you run the template from Azure PowerShell, the Azure CLI, or the Azure portal, ARM will be expecting the user to input the values for these two parameters. If the user is not providing any parameter, then the deployment will fail.
There are more options available for each parameter like minLength and maxLength to specify the minimum and maximum length of the parameter if the parameter is a string. Then, maxValue and minValue specify the minimum and maximum values of the parameter in the case of integers. Then you have defaultValue, which will be considered as the value of the parameter if the user is not providing any value for the parameter when the template runs. Also, you can specify the list of allowed values via allowedValues. In VS Code, it’s not hard to understand this, thanks to the Azure Resource Manager extension and IntelliSense.