Bicep Best Practices

Azure Bicep is a Domain Specific Language (DSL) for deploying Azure resources declaratively. It is a language that is designed to be a more readable and maintainable way to define Azure resources.

Bicep comes with a linter that detects various faults, but also comes with online best practices which are not completely covered by the linter.

Web App Basic Linux

The following is a Bicep file that deploys a web app with a Linux app service plan. It is the microsoft.web/webapp-basic-linux/main.bicep sample template in the bicep playground.

web-app-basic-linux.bicep

@description('Base name of the resource such as web app name and app service plan ')
@minLength(2)
param webAppName string = 'AzureLinuxApp'

@description('The SKU of App Service Plan ')
param sku string = 'S1'

@description('The Runtime stack of current web app')
param linuxFxVersion string = 'php|7.4'

@description('Location for all resources.')
param location string = resourceGroup().location

var webAppPortalName = '${webAppName}-webapp'
#disable-next-line genaiscript
var appServicePlanName = 'AppServicePlan-${webAppName}'

resource appServicePlan 'Microsoft.Web/serverfarms@2022-03-01' = {
  name: appServicePlanName
  location: location
  sku: {
    name: sku
  }
  kind: 'linux'
  properties: {
    reserved: true
  }
}

resource webAppPortal 'Microsoft.Web/sites@2022-03-01' = {
  name: webAppPortalName
  location: location
  kind: 'app'
  properties: {
    serverFarmId: appServicePlan.id
    siteConfig: {
      linuxFxVersion: linuxFxVersion
      ftpsState: 'FtpsOnly'
    }
    httpsOnly: true
  }
  identity: {
    type: 'SystemAssigned'
  }
}

Script

The file is linter clean, but some improvements could be made with best practices. The following script will apply best practices to the Bicep file.

bicep-best-practices.genai.mjs

script({
    title: "Bicep Best Practices",
    temperature: 0,
    system: ["system", "system.annotations"],
    accept: ".bicep",
})

def("FILE", env.files, { endsWith: ".bicep" })

$`You are an expert at Azure Bicep.

Review the bicep in FILE and generate errors to enhance the script base on best practices
(https://learn.microsoft.com/en-us/azure/azure-resource-manager/bicep/best-practices).

- Generate the top 3 most important annotations.
- Limit range to a single line.
- Do NOT generate notes.
- If a line starts with "#disable-next-line genaiscript", ignore the next line.
`

• line numbers are added to the file content to help the LLM precisely locate the issues.

def("FILE", env.files, { endsWith: ".bicep", lineNumbers: true })

• the script uses a builtin support for annotations to generate parseable warnings and errors. Annotations are automatically integrated as problems in VSCode or as build errors in the CI/CD pipeline.

$`... and generate annotations ...`

• added support to ignore false positives using the #disable-next-line genaiscript comment

$`- If a line starts with "#disable-next-line genaiscript", ignore the next line.`

• GPT-4 already knows about the best practices for Bicep, no need to repeat them!

Results

The LLM generates 3 annotations for the Bicep file. The annotations are surfaced as squiggly lines in VSCode.