Merge pull request #287100 from mumian/0919-linter-what-if-short-circuiting

new linter rule - what-if-short-circuiting

Author: Court72

articles/azure-resource-manager/bicep/bicep-config-linter.md

@@ -3,7 +3,7 @@ title: Linter settings for Bicep config
 description: Describes how to customize configuration values for the Bicep linter
 ms.topic: conceptual
 ms.custom: devx-track-bicep
-ms.date: 07/30/2024
+ms.date: 09/19/2024
 ---
 
 # Add linter settings in the Bicep config file
@@ -135,6 +135,9 @@ The following example shows the rules that are available for configuration.
         },
         "use-stable-vm-image": {
           "level": "warning"
+        },
+        "what-if-short-circuiting": {
+          "level": "warning"
         }
       }
     }

articles/azure-resource-manager/bicep/linter-rule-what-if-short-circuiting.md

@@ -0,0 +1,80 @@
+---
+title: Linter rule - what-if short circuiting
+description: Linter rule - what-if short circuiting
+ms.topic: reference
+ms.custom: devx-track-bicep
+ms.date: 09/19/2024
+---
+
+# Linter rule - what-if short circuiting
+
+This rule detects when runtime values are passed as parameters to modules, which in turn use them to determine resource IDs (such as when the parameter is used to determine the name, subscriptionId, resourceGroup, condition, scope, or apiVersion of one or more resources within the module) , and flags potential what-if short-circuiting.
+
+> [!NOTE]
+> This rule is off by default, change the level in [bicepconfig.json](./bicep-config-linter.md) to enable it.
+
+## Linter rule code
+
+Use the following value in the [Bicep configuration file](bicep-config-linter.md) to customize rule settings:
+
+`what-if-short-circuiting`
+
+## Solution
+
+This rule checks for runtime values used to determine resource IDs within modules. It alerts you if your Bicep code could cause what-if short-circuiting. In the example below, **appServiceOutputs** and **appServiceTests** would be flagged for what-if short-circuiting because they pass runtime values as parameters to the module, which uses them when naming the resource:
+
+**main.bicep**
+
+```bicep
+resource storageAccount 'Microsoft.Storage/storageAccounts@2023-05-01' = {
+  name: 'storageAccountName'
+  location: 'eastus'
+  sku: {
+    name: 'Standard_LRS'
+  }
+  kind: 'StorageV2'
+}
+
+module appServiceModule 'modules/appService.bicep' = {
+  name: 'appService2'
+  params: {
+    appServiceName: 'test'
+  }
+}
+
+module appServiceOutputs 'modules/appService.bicep' = {
+  name: 'appService3'
+  params: {
+    appServiceName: appServiceModule.outputs.outputName
+  }
+}
+
+module appServiceTest 'modules/appService.bicep' = {
+  name:'test3'
+  params: {
+    appServiceName: storageAccount.properties.accessTier
+  }
+}
+```
+
+**modules/appService.bicep**
+
+```bicep
+param appServiceName string
+
+resource appServiceApp 'Microsoft.Web/sites@2023-12-01' = {
+  name: appServiceName
+  location: 'eastus'
+  properties: {
+    httpsOnly: true
+  }
+}
+
+output outputName string = 'outputName'
+```
+
+To avoid this issue, use deployment-time constants for values that are used in determining resource IDs.
+
+## Next steps
+
+For more information about the linter, see [Use Bicep linter](./linter.md).

articles/azure-resource-manager/bicep/linter.md

@@ -3,7 +3,7 @@ title: Use Bicep linter
 description: Learn how to use Bicep linter.
 ms.topic: how-to
 ms.custom: devx-track-bicep
-ms.date: 07/30/2024
+ms.date: 09/19/2024
 ---
 
 # Use Bicep linter
@@ -55,6 +55,7 @@ The default set of linter rules is minimal and taken from [arm-ttk test cases](.
 - [use-secure-value-for-secure-inputs](./linter-rule-use-secure-value-for-secure-inputs.md)
 - [use-stable-resource-identifiers](./linter-rule-use-stable-resource-identifier.md)
 - [use-stable-vm-image](./linter-rule-use-stable-vm-image.md)
+- [what-if-short-circuiting](./linter-rule-what-if-short-circuiting.md)
 
 You can customize how the linter rules are applied. To overwrite the default settings, add a **bicepconfig.json** file and apply custom settings. For more information about applying those settings, see [Add custom settings in the Bicep config file](bicep-config-linter.md).
 

articles/azure-resource-manager/bicep/toc.yml

@@ -563,6 +563,9 @@
       - name: Use stable VM image
         displayName: linter
         href: linter-rule-use-stable-vm-image.md
+      - name: What-if short-circuiting
+        displayName: linter
+        href: linter-rule-what-if-short-circuiting.md
   - name: Deploy
     items:
     - name: What-if check