Bicep File Structure

Bicep File Structure

A Bicep file is composed of several key elements, each serving a distinct purpose in resource deployment:​

• Metadata (metadata): Provides supplementary information about the Bicep file, such as descriptions or versioning details.​

• Target Scope (targetScope): Defines the deployment scope, indicating whether the resources are deployed at the resource group, subscription, management group, or tenant level.​

• Parameters (param): Allow customization of deployments by accepting input values during deployment.​

• Variables (var): Store computed values or constants to simplify expressions within the Bicep file.​

• Resources (resource): Declare the Azure resources to be deployed, specifying their types, properties, and configurations.​

• Modules (module): Encapsulate reusable Bicep code, enabling modularization and better organization of complex deployments.​

• Outputs (output): Define values to be returned after deployment, which can be used for subsequent operations or referenced in other deployments.​

Bicep Syntax Elements

Metadata

The metadata keyword is used to add descriptive information to your Bicep file. This can include details like the purpose of the file or version information.​

metadata description = 'Deploys a storage account and a web app'

Target Scope

The targetScope keyword specifies the level at which the deployment is executed. The default scope is resourceGroup. Other valid scopes include subscription, managementGroup, and tenant.​

targetScope = 'resourceGroup'

Parameters

Parameters allow you to pass values into the Bicep file during deployment, making your templates more flexible and reusable.​

@description('The prefix to use for the storage account name.')
@minLength(3)
@maxLength(11)
param storagePrefix string

In this example, the storagePrefix parameter is defined with a description and length constraints.​

Variables

Variables store values that are derived from parameters or computed expressions, simplifying complex expressions within your Bicep file.​

var uniqueStorageName = '${storagePrefix}${uniqueString(resourceGroup().id)}'

Here, uniqueStorageName combines the storagePrefix parameter with a unique string based on the resource group ID.​

Resources

The resource keyword is used to declare Azure resources to be deployed. Each resource declaration includes a symbolic name, resource type with API version, and a set of properties.​

resource storageAccount 'Microsoft.Storage/storageAccounts@2023-04-01' = {
  name: uniqueStorageName
  location: location
  sku: {
    name: storageSKU
  }
  kind: 'StorageV2'
  properties: {
    supportsHttpsTrafficOnly: true
  }
}

This example defines a storage account resource with specific configurations.​

Modules

Modules enable you to encapsulate and reuse Bicep code across different deployments, promoting modularity and maintainability.​

bicepCopyEditmodule webModule './webApp.bicep' = {
  name: 'webDeploy'
  params: {
    skuName: 'S1'
    location: location
  }
}

In this snippet, the webModule module is invoked, passing parameters to configure its deployment.​

Outputs

Outputs define values that are returned after the deployment is complete, which can be useful for retrieving resource properties or passing information to other deployments.​

output storageEndpoint object = storageAccount.properties.primaryEndpoints

This output returns the primary endpoints of the deployed storage account.​

Decorators

Decorators in Bicep are annotations that provide additional information or constraints for parameters, variables, resources, modules, outputs, functions, and user-defined data types. They are prefixed with the @ symbol and placed above the declaration they modify.​

Common decorators include:​

• @description(): Adds a description to the element.​

• @minLength(): Specifies the minimum length for strings or arrays.​

• @maxLength(): Specifies the maximum length for strings or arrays.​

• @allowed(): Defines an allowed set of values for a parameter.​

• @secure(): Marks a parameter as secure, ensuring its value isn't exposed in deployment outputs or logs.​

For a comprehensive list of decorators and their usage, refer to the Bicep file structure and syntax documentation.