Orphaned Rules - 2 Rules

When teams start with Bicep, it’s tempting to keep everything in a single large .bicep file. While this works for small experiments, it quickly becomes unmanageable in real-world solutions. Changes become risky, duplication creeps in, and debugging is painful.

That’s why using Bicep modules—small, reusable templates—is the recommended approach. Modules let you break down complex infrastructure into logical components, making your code easier to maintain, test, and share across projects.

Why use module templates?

• Reusability – Define resources once and reuse them across environments (e.g. dev, test, prod).
• Maintainability – Smaller files are easier to read and troubleshoot.
• Consistency – Teams can follow the same patterns, reducing misconfiguration.
• Scalability – Large deployments can be composed of well-tested building blocks.

Example: Without vs With Modules

// main.bicep (all-in-one)
resource storageAccount 'Microsoft.Storage/storageAccounts@2022-09-01' = {
  name: 'myuniquestorage'
  location: resourceGroup().location
  sku: {
    name: 'Standard_LRS'
  }
  kind: 'StorageV2'
}

resource appInsights 'Microsoft.Insights/components@2020-02-02' = {
  name: 'myappinsights'
  location: resourceGroup().location
  kind: 'web'
  properties: {
    Application_Type: 'web'
  }
}

// storageAccount.bicep (module)
param storageName string
param location string

resource storageAccount 'Microsoft.Storage/storageAccounts@2022-09-01' = {
  name: storageName
  location: location
  sku: {
    name: 'Standard_LRS'
  }
  kind: 'StorageV2'
}

// appInsights.bicep (module)
param appInsightsName string
param location string

resource appInsights 'Microsoft.Insights/components@2020-02-02' = {
  name: appInsightsName
  location: location
  kind: 'web'
  properties: {
    Application_Type: 'web'
  }
}

// main.bicep
module storage './storageAccount.bicep' = {
  name: 'storageDeployment'
  params: {
    storageName: 'myuniquestorage'
    location: resourceGroup().location
  }
}

module appInsights './appInsights.bicep' = {
  name: 'appInsightsDeployment'
  params: {
    appInsightsName: 'myappinsights'
    location: resourceGroup().location
  }
}

Best practices for modules

• Keep modules small – A module should represent a logical unit (e.g. a storage account, app service, or network).
• Use parameters and outputs – Define clear inputs and outputs so modules are flexible.
• Version control – Store commonly used modules in a shared repo or registry.
• Validate early – Test modules in isolation before plugging them into larger deployments.

By treating your Bicep modules like building blocks, you create a clean, reusable infrastructure-as-code foundation that grows with your projects.

Migrating legacy applications to Azure without first performing a readiness assessment can lead to unexpected failures or hidden blockers. Using Azure’s App Service Migration Assistant, an on-premises web application was assessed and packaged for migration efficiently through Microsoft’s PowerShell scripts.

By following this structured, automated approach, migrations are faster, clearer, and more predictable.

Why use Azure Migrate + App Service Migration Assistant?

✅ Pros

• Fast process – Full assessment and packaging completed within 30-60 minutes when paired with SysAdmin who had the knowledge of the application's on-premises server.
• Clear, actionable reports – Output is easy to interpret, helping teams resolve migration blockers quickly.
• Repeatable and scalable – Scripts are well-documented, ideal for reuse across multiple migrations.

⚠️ Cons

• Requires local administrator access – Scripts must be run directly on the server (coordination with SysAdmin required) dev cannot do this by himself.
• No remote execution – Assessment cannot be initiated remotely.

Recommendation

Use Azure Migrate and the App Service Migration Assistant before migrating any web application to Azure. This toolset helps identify blockers early and reduces time spent resolving avoidable issues during actual migration.

For web applications, always run the assessment scripts in advance and generate migration packages using Microsoft’s tools. This will help your team feel more confident in the migration process and avoid unnecessary surprises.

Useful Resources

• 🔗 Official Azure App Service Migration Assistant Documentation
• 🔗 App Service Migration Assistant – Official Azure Blog Announcement
• ▶️ Video: Azure App Service Migration Assistant Demo