Respond to PR feedback

- Write the connectionString to the manifest if it is provided.
- Use DistributedApplicationException

src/Aspire.Hosting/Postgres/IPostgresComponent.cs

@@ -7,5 +7,5 @@ namespace Aspire.Hosting.Postgres;
 
 public interface IPostgresComponent : IDistributedApplicationComponent
 {
-    string GetConnectionString(string? databaseName = null);
+    string? GetConnectionString(string? databaseName = null);
 }

src/Aspire.Hosting/Postgres/PostgresBuilderExtensions.cs

@@ -32,15 +32,25 @@ public static IDistributedApplicationComponentBuilder<PostgresContainerComponent
                       });
     }
 
-    public static IDistributedApplicationComponentBuilder<PostgresComponent> AddPostgres(this IDistributedApplicationBuilder builder, string name, string connectionString)
+    public static IDistributedApplicationComponentBuilder<PostgresComponent> AddPostgres(this IDistributedApplicationBuilder builder, string name, string? connectionString)
     {
-        return builder.AddComponent(new PostgresComponent(name, connectionString))
-            .WithAnnotation(new ManifestPublishingCallbackAnnotation(WritePostgresComponentToManifest));
+        var postgres = new PostgresComponent(name, connectionString);
+
+        return builder.AddComponent(postgres)
+            .WithAnnotation(new ManifestPublishingCallbackAnnotation((jsonWriter, cancellationToken) =>
+                WritePostgresComponentToManifest(jsonWriter, postgres.GetConnectionString(), cancellationToken)));
     }
 
-    private static async Task WritePostgresComponentToManifest(Utf8JsonWriter jsonWriter, CancellationToken cancellationToken)
+    private static Task WritePostgresComponentToManifest(Utf8JsonWriter jsonWriter, CancellationToken cancellationToken) =>
+        WritePostgresComponentToManifest(jsonWriter, null, cancellationToken);
+
+    private static async Task WritePostgresComponentToManifest(Utf8JsonWriter jsonWriter, string? connectionString, CancellationToken cancellationToken)
     {
         jsonWriter.WriteString("type", "postgres.v1");
+        if (!string.IsNullOrEmpty(connectionString))
+        {
+            jsonWriter.WriteString("connectionString", connectionString);
+        }
         await jsonWriter.FlushAsync(cancellationToken).ConfigureAwait(false);
     }
 
@@ -50,18 +60,25 @@ private static async Task WritePostgresComponentToManifest(Utf8JsonWriter jsonWr
     public static IDistributedApplicationComponentBuilder<T> WithPostgresDatabase<T>(this IDistributedApplicationComponentBuilder<T> builder, IDistributedApplicationComponentBuilder<IPostgresComponent> postgresBuilder, string? databaseName = null, string? connectionName = null)
         where T : IDistributedApplicationComponentWithEnvironment
     {
+        var postgres = postgresBuilder.Component;
         connectionName = connectionName ?? postgresBuilder.Component.Name;
 
         return builder.WithEnvironment((context) =>
         {
+            var connectionStringName = $"{ConnectionStringEnvironmentName}{connectionName}";
+
             if (context.PublisherName == "manifest")
             {
-                context.EnvironmentVariables[$"{ConnectionStringEnvironmentName}{connectionName}"] = $"{{{postgresBuilder.Component.Name}.connectionString}}";
+                context.EnvironmentVariables[connectionStringName] = $"{{{postgres.Name}.connectionString}}";
                 return;
             }
 
-            var connectionString = postgresBuilder.Component.GetConnectionString(databaseName);
-            context.EnvironmentVariables[$"{ConnectionStringEnvironmentName}{connectionName}"] = connectionString;
+            var connectionString = postgres.GetConnectionString(databaseName);
+            if (string.IsNullOrEmpty(connectionString))
+            {
+                throw new DistributedApplicationException($"A connection string for Postgres '{postgres.Name}' could not be retrieved.");
+            }
+            context.EnvironmentVariables[connectionStringName] = connectionString;
         });
     }
 }

src/Aspire.Hosting/Postgres/PostgresComponent.cs

@@ -5,9 +5,10 @@
 
 namespace Aspire.Hosting.Postgres;
 
-public class PostgresComponent(string name, string connectionString) : DistributedApplicationComponent(name), IPostgresComponent
+public class PostgresComponent(string name, string? connectionString) : DistributedApplicationComponent(name), IPostgresComponent
 {
-    public string GetConnectionString(string? databaseName = null) =>
+    public string? GetConnectionString(string? databaseName = null) =>
+        connectionString is null ? null :
         databaseName is null ?
             connectionString :
             connectionString.EndsWith(';') ?

src/Aspire.Hosting/Postgres/PostgresContainerComponent.cs

@@ -11,12 +11,12 @@ public string GetConnectionString(string? databaseName = null)
     {
         if (!this.TryGetAllocatedEndPoints(out var allocatedEndpoints))
         {
-            throw new InvalidOperationException("Expected allocated endpoints!");
+            throw new DistributedApplicationException("Expected allocated endpoints!");
         }
 
         if (!this.TryGetLastAnnotation<PostgresPasswordAnnotation>(out var passwordAnnotation))
         {
-            throw new InvalidOperationException($"Postgres does not have a password set!");
+            throw new DistributedApplicationException($"Postgres does not have a password set!");
         }
 
         var allocatedEndpoint = allocatedEndpoints.Single(); // We should only have one endpoint for Postgres.

src/Aspire.Hosting/Redis/IRedisComponent.cs

@@ -7,5 +7,5 @@ namespace Aspire.Hosting.Redis;
 
 public interface IRedisComponent : IDistributedApplicationComponent
 {
-    string GetConnectionString();
+    string? GetConnectionString();
 }

src/Aspire.Hosting/Redis/RedisBuilderExtensions.cs

@@ -22,34 +22,49 @@ public static IDistributedApplicationComponentBuilder<RedisContainerComponent> A
         return componentBuilder;
     }
 
-    public static IDistributedApplicationComponentBuilder<RedisComponent> AddRedis(this IDistributedApplicationBuilder builder, string name, string connectionString)
+    public static IDistributedApplicationComponentBuilder<RedisComponent> AddRedis(this IDistributedApplicationBuilder builder, string name, string? connectionString)
     {
-        return builder.AddComponent(new RedisComponent(name, connectionString))
-            .WithAnnotation(new ManifestPublishingCallbackAnnotation(WriteRedisComponentToManifest));
+        var redis = new RedisComponent(name, connectionString);
+
+        return builder.AddComponent(redis)
+            .WithAnnotation(new ManifestPublishingCallbackAnnotation((jsonWriter, cancellationToken) =>
+                WriteRedisComponentToManifest(jsonWriter, redis.GetConnectionString(), cancellationToken)));
     }
 
-    private static async Task WriteRedisComponentToManifest(Utf8JsonWriter jsonWriter, CancellationToken cancellationToken)
+    private static Task WriteRedisComponentToManifest(Utf8JsonWriter jsonWriter, CancellationToken cancellationToken) =>
+        WriteRedisComponentToManifest(jsonWriter, null, cancellationToken);
+
+    private static async Task WriteRedisComponentToManifest(Utf8JsonWriter jsonWriter, string? connectionString, CancellationToken cancellationToken)
     {
         jsonWriter.WriteString("type", "redis.v1");
+        if (!string.IsNullOrEmpty(connectionString))
+        {
+            jsonWriter.WriteString("connectionString", connectionString);
+        }
         await jsonWriter.FlushAsync(cancellationToken).ConfigureAwait(false);
     }
 
     public static IDistributedApplicationComponentBuilder<T> WithRedis<T>(this IDistributedApplicationComponentBuilder<T> builder, IDistributedApplicationComponentBuilder<IRedisComponent> redisBuilder, string? connectionName = null)
         where T : IDistributedApplicationComponentWithEnvironment
     {
-        connectionName = connectionName ?? redisBuilder.Component.Name;
+        var redis = redisBuilder.Component;
+        connectionName = connectionName ?? redis.Name;
 
         return builder.WithEnvironment((context) =>
         {
             var connectionStringName = $"{ConnectionStringEnvironmentName}{connectionName}";
 
             if (context.PublisherName == "manifest")
             {
-                context.EnvironmentVariables[connectionStringName] = $"{{{redisBuilder.Component.Name}.connectionString}}";
+                context.EnvironmentVariables[connectionStringName] = $"{{{redis.Name}.connectionString}}";
                 return;
             }
 
-            var connectionString = redisBuilder.Component.GetConnectionString();
+            var connectionString = redis.GetConnectionString();
+            if (string.IsNullOrEmpty(connectionString))
+            {
+                throw new DistributedApplicationException($"A connection string for Redis '{redis.Name}' could not be retrieved.");
+            }
             context.EnvironmentVariables[connectionStringName] = connectionString;
         });
     }

src/Aspire.Hosting/Redis/RedisComponent.cs

@@ -5,7 +5,7 @@
 
 namespace Aspire.Hosting.Redis;
 
-public class RedisComponent(string name, string connectionString) : DistributedApplicationComponent(name), IRedisComponent
+public class RedisComponent(string name, string? connectionString) : DistributedApplicationComponent(name), IRedisComponent
 {
-    public string GetConnectionString() => connectionString;
+    public string? GetConnectionString() => connectionString;
 }

src/Aspire.Hosting/SqlServer/ISqlServerComponent.cs

@@ -7,5 +7,5 @@ namespace Aspire.Hosting.SqlServer;
 
 public interface ISqlServerComponent : IDistributedApplicationComponent
 {
-    string GetConnectionString(string? databaseName = null);
+    string? GetConnectionString(string? databaseName = null);
 }

src/Aspire.Hosting/SqlServer/SqlServerBuilderExtensions.cs

@@ -24,21 +24,32 @@ public static IDistributedApplicationComponentBuilder<SqlServerContainerComponen
         return componentBuilder;
     }
 
-    public static IDistributedApplicationComponentBuilder<SqlServerComponent> AddSqlServer(this IDistributedApplicationBuilder builder, string name, string connectionString)
+    public static IDistributedApplicationComponentBuilder<SqlServerComponent> AddSqlServer(this IDistributedApplicationBuilder builder, string name, string? connectionString)
     {
-        return builder.AddComponent(new SqlServerComponent(name, connectionString))
-            .WithAnnotation(new ManifestPublishingCallbackAnnotation(WriteSqlServerComponentToManifest));
+        var sqlServer = new SqlServerComponent(name, connectionString);
+
+        return builder.AddComponent(sqlServer)
+            .WithAnnotation(new ManifestPublishingCallbackAnnotation((jsonWriter, cancellationToken) =>
+                WriteSqlServerComponentToManifest(jsonWriter, sqlServer.GetConnectionString(), cancellationToken)));
     }
 
-    private static async Task WriteSqlServerComponentToManifest(Utf8JsonWriter jsonWriter, CancellationToken cancellationToken)
+    private static Task WriteSqlServerComponentToManifest(Utf8JsonWriter jsonWriter, CancellationToken cancellationToken) =>
+        WriteSqlServerComponentToManifest(jsonWriter, null, cancellationToken);
+
+    private static async Task WriteSqlServerComponentToManifest(Utf8JsonWriter jsonWriter, string? connectionString, CancellationToken cancellationToken)
     {
         jsonWriter.WriteString("type", "sqlserver.v1");
+        if (!string.IsNullOrEmpty(connectionString))
+        {
+            jsonWriter.WriteString("connectionString", connectionString);
+        }
         await jsonWriter.FlushAsync(cancellationToken).ConfigureAwait(false);
     }
 
     public static IDistributedApplicationComponentBuilder<T> WithSqlServer<T>(this IDistributedApplicationComponentBuilder<T> builder, IDistributedApplicationComponentBuilder<SqlServerContainerComponent> sqlBuilder, string? databaseName, string? connectionName = null)
         where T : IDistributedApplicationComponentWithEnvironment
     {
+        var sql = sqlBuilder.Component;
         connectionName = connectionName ?? sqlBuilder.Component.Name;
 
         return builder.WithEnvironment((context) =>
@@ -47,11 +58,15 @@ public static IDistributedApplicationComponentBuilder<T> WithSqlServer<T>(this I
 
             if (context.PublisherName == "manifest")
             {
-                context.EnvironmentVariables[connectionStringName] = $"{{{sqlBuilder.Component.Name}.connectionString}}";
+                context.EnvironmentVariables[connectionStringName] = $"{{{sql.Name}.connectionString}}";
                 return;
             }
 
-            var connectionString = sqlBuilder.Component.GetConnectionString(databaseName);
+            var connectionString = sql.GetConnectionString(databaseName);
+            if (string.IsNullOrEmpty(connectionString))
+            {
+                throw new DistributedApplicationException($"A connection string for SqlServer '{sql.Name}' could not be retrieved.");
+            }
             context.EnvironmentVariables[connectionStringName] = connectionString;
         });
     }

src/Aspire.Hosting/SqlServer/SqlServerComponent.cs

@@ -5,9 +5,10 @@
 
 namespace Aspire.Hosting.SqlServer;
 
-public class SqlServerComponent(string name, string connectionString) : DistributedApplicationComponent(name), ISqlServerComponent
+public class SqlServerComponent(string name, string? connectionString) : DistributedApplicationComponent(name), ISqlServerComponent
 {
-    public string GetConnectionString(string? databaseName = null) =>
+    public string? GetConnectionString(string? databaseName = null) =>
+        connectionString is null ? null :
         databaseName is null ?
             connectionString :
             connectionString.EndsWith(';') ?