fix: Reuse Log analytics across subscriptions

Author: Prajwal-Microsoft

infra/container_app/deploy_container_app_env.bicep

@@ -4,10 +4,11 @@ param location string
 
 param logAnalyticsWorkspaceName string
 param logAnalyticsWorkspaceResourceGroup string
+param logAnalyticsWorkspaceSubscription string
 
 resource logAnalyticsWorkspace 'Microsoft.OperationalInsights/workspaces@2023-09-01' existing = {
   name: logAnalyticsWorkspaceName
-  scope: resourceGroup(logAnalyticsWorkspaceResourceGroup)
+  scope: resourceGroup(logAnalyticsWorkspaceSubscription, logAnalyticsWorkspaceResourceGroup)
 }
 
 resource containerRegistryReader 'Microsoft.ManagedIdentity/userAssignedIdentities@2023-01-31' = {

infra/deploy_app_insights.bicep

@@ -5,12 +5,13 @@ param logAnalyticsWorkspaceName string
 param existingLogAnalyticsWorkspaceId string = ''
 
 var useExisting = !empty(existingLogAnalyticsWorkspaceId)
+var existingLawSubscriptionId = useExisting ? split(existingLogAnalyticsWorkspaceId, '/')[2] : ''
 var existingLawResourceGroup = useExisting ? split(existingLogAnalyticsWorkspaceId, '/')[4] : ''
 var existingLawName = useExisting ? split(existingLogAnalyticsWorkspaceId, '/')[8] : ''
 
 resource existingLogAnalyticsWorkspace 'Microsoft.OperationalInsights/workspaces@2020-08-01' existing = if (useExisting) {
   name: existingLawName
-  scope: resourceGroup(existingLawResourceGroup)
+  scope: resourceGroup(existingLawSubscriptionId, existingLawResourceGroup)
 }
 
 resource logAnalyticsWorkspace 'Microsoft.OperationalInsights/workspaces@2023-09-01' = if (!useExisting) {
@@ -48,4 +49,5 @@ resource applicationInsights 'Microsoft.Insights/components@2020-02-02' = {
 
 output id string = applicationInsights.id
 output logAnalyticsWorkspaceName string = useExisting ? existingLogAnalyticsWorkspace.name : logAnalyticsWorkspace.name
+output logAnalyticsWorkspaceSubscription string = useExisting ? existingLawSubscriptionId : split(subscription().id, '/')[2]
 output logAnalyticsWorkspaceResourceGroup string = useExisting ? existingLawResourceGroup : resourceGroup().name

infra/main.bicep

@@ -164,6 +164,7 @@ module containerAppEnv './container_app/deploy_container_app_env.bicep' = {
     location: secondaryLocation
     logAnalyticsWorkspaceName: applicationInsights.outputs.logAnalyticsWorkspaceName
     logAnalyticsWorkspaceResourceGroup: applicationInsights.outputs.logAnalyticsWorkspaceResourceGroup
+    logAnalyticsWorkspaceSubscription: applicationInsights.outputs.logAnalyticsWorkspaceSubscription
   }
 }