Don't set properties on existing Azure SQL server resources

src/Aspire.Hosting.Azure.Sql/AzureSqlExtensions.cs

@@ -205,14 +205,6 @@ private static void CreateSqlServer(
         {
             var resource = SqlServer.FromExisting(identifier);
             resource.Name = name;
-            resource.Administrators = new ServerExternalAdministrator()
-            {
-                AdministratorType = SqlAdministratorType.ActiveDirectory,
-                IsAzureADOnlyAuthenticationEnabled = true,
-                Sid = principalIdParameter,
-                Login = principalNameParameter,
-                TenantId = BicepFunction.GetSubscription().TenantId
-            };
             return resource;
         },
         (infrastructure) =>
@@ -248,7 +240,10 @@ private static void CreateSqlServer(
             // the principalType.
             var principalTypeParameter = new ProvisioningParameter(AzureBicepResource.KnownParameters.PrincipalType, typeof(string));
             infrastructure.Add(principalTypeParameter);
-            sqlServer.Administrators.PrincipalType = principalTypeParameter;
+            if (!sqlServer.IsExistingResource)
+            {
+                sqlServer.Administrators.PrincipalType = principalTypeParameter;
+            }
 
             infrastructure.Add(new SqlFirewallRule("sqlFirewallRule_AllowAllIps")
             {

tests/Aspire.Hosting.Azure.Tests/ExistingAzureResourceTests.cs

@@ -1122,15 +1122,6 @@ param existingResourceName string
 
             resource sqlServer 'Microsoft.Sql/servers@2021-11-01' existing = {
               name: existingResourceName
-              properties: {
-                administrators: {
-                  administratorType: 'ActiveDirectory'
-                  login: principalName
-                  sid: principalId
-                  tenantId: subscription().tenantId
-                  azureADOnlyAuthentication: true
-                }
-              }
             }
 
             resource sqlFirewallRule_AllowAllAzureIps 'Microsoft.Sql/servers/firewallRules@2021-11-01' = {
@@ -1190,16 +1181,6 @@ param principalType string
 
             resource sqlServer 'Microsoft.Sql/servers@2021-11-01' existing = {
               name: existingResourceName
-              properties: {
-                administrators: {
-                  administratorType: 'ActiveDirectory'
-                  principalType: principalType
-                  login: principalName
-                  sid: principalId
-                  tenantId: subscription().tenantId
-                  azureADOnlyAuthentication: true
-                }
-              }
             }
 
             resource sqlFirewallRule_AllowAllAzureIps 'Microsoft.Sql/servers/firewallRules@2021-11-01' = {
@@ -1372,13 +1353,13 @@ public async Task SupportsExistingAzureApplicationInsightsWithResourceGroup()
         var expectedBicep = """
             @description('The location for the resource(s) to be deployed.')
             param location string = resourceGroup().location
-    
+
             param existingResourceName string
-    
+
             resource appInsights 'Microsoft.Insights/components@2020-02-02' existing = {
               name: existingResourceName
             }
-    
+
             output appInsightsConnectionString string = appInsights.properties.ConnectionString
             """;
 
@@ -1419,17 +1400,17 @@ public async Task SupportsExistingAzureOpenAIWithResourceGroup()
         var expectedBicep = """
             @description('The location for the resource(s) to be deployed.')
             param location string = resourceGroup().location
-    
+
             param existingResourceName string
-    
+
             param principalType string
-    
+
             param principalId string
-    
+
             resource openAI 'Microsoft.CognitiveServices/accounts@2024-10-01' existing = {
               name: existingResourceName
             }
-    
+
             resource openAI_CognitiveServicesOpenAIContributor 'Microsoft.Authorization/roleAssignments@2022-04-01' = {
               name: guid(openAI.id, principalId, subscriptionResourceId('Microsoft.Authorization/roleDefinitions', 'a001fd3d-188f-4b5d-821b-7da978bf7442'))
               properties: {
@@ -1439,7 +1420,7 @@ param principalId string
               }
               scope: openAI
             }
-    
+
             resource mymodel 'Microsoft.CognitiveServices/accounts/deployments@2024-10-01' = {
               name: 'mymodel'
               properties: {