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Fix MCP Inspector auto-opening browser when using aspire run #789

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Merged
merged 3 commits into from
Aug 7, 2025
Merged

Fix MCP Inspector auto-opening browser when using aspire run #789

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2122c11
Initial plan
Copilot Aug 6, 2025
7b74110
Fix MCP Inspector auto-opening browser when using aspire run
Copilot Aug 6, 2025
7f3c4de
Removing the test as it can't run as a unit test
aaronpowell Aug 7, 2025
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98 changes: 51 additions & 47 deletions src/CommunityToolkit.Aspire.Hosting.McpInspector/McpInspectorResourceBuilderExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,14 +17,15 @@ public static class McpInspectorResourceBuilderExtensions
/// <param name="inspectorVersion">The version of the Inspector app to use</param>
public static IResourceBuilder<McpInspectorResource> AddMcpInspector(this IDistributedApplicationBuilder builder, [ResourceName] string name, int clientPort = 6274, int serverPort = 6277, string inspectorVersion = McpInspectorResource.InspectorVersion)
{
var resource = builder.AddResource(new McpInspectorResource(name))
return builder.AddResource(new McpInspectorResource(name))
.WithArgs(["-y", $"@modelcontextprotocol/inspector@{inspectorVersion}"])
.ExcludeFromManifest()
.WithHttpEndpoint(isProxied: false, port: clientPort, env: "CLIENT_PORT", name: McpInspectorResource.ClientEndpointName)
.WithHttpEndpoint(isProxied: false, port: serverPort, env: "SERVER_PORT", name: McpInspectorResource.ServerProxyEndpointName)
.WithEnvironment("DANGEROUSLY_OMIT_AUTH", "true")
.WithHttpHealthCheck("/", endpointName: McpInspectorResource.ClientEndpointName)
.WithHttpHealthCheck("/config", endpointName: McpInspectorResource.ServerProxyEndpointName)
.WithEnvironment("MCP_AUTO_OPEN_ENABLED", "false")
.WithUrlForEndpoint(McpInspectorResource.ClientEndpointName, annotation =>
{
annotation.DisplayText = "Client";
Expand All @@ -34,41 +35,38 @@ public static IResourceBuilder<McpInspectorResource> AddMcpInspector(this IDistr
{
annotation.DisplayText = "Server Proxy";
annotation.DisplayOrder = 1;
});

builder.Eventing.Subscribe<BeforeResourceStartedEvent>(resource.Resource, async (@event, ct) =>
{
if (@event.Resource is not McpInspectorResource inspectorResource)
{
return;
}

if (inspectorResource.DefaultMcpServer is null && inspectorResource.McpServers.Count > 0)
})
.OnBeforeResourceStarted(async (inspectorResource, @event, ct) =>
{
throw new InvalidOperationException("No default MCP server has been configured for the MCP Inspector resource, yet servers have been provided.");
}
if (inspectorResource.DefaultMcpServer is null && inspectorResource.McpServers.Count > 0)
{
throw new InvalidOperationException("No default MCP server has been configured for the MCP Inspector resource, yet servers have been provided.");
}

var servers = inspectorResource.McpServers.ToDictionary(s => s.Name, s => new
{
transport = s.TransportType switch
var servers = inspectorResource.McpServers.ToDictionary(s => s.Name, s => new
{
McpTransportType.StreamableHttp => "streamable-http",
transport = s.TransportType switch
{
McpTransportType.StreamableHttp => "streamable-http",
#pragma warning disable CS0618
McpTransportType.Sse => "sse",
McpTransportType.Sse => "sse",
#pragma warning restore CS0618
_ => throw new NotSupportedException($"The transport type {s.TransportType} is not supported.")
},
endpoint = s.Endpoint.Url
});
_ => throw new NotSupportedException($"The transport type {s.TransportType} is not supported.")
},
endpoint = s.Endpoint.Url
});

var config = new { mcpServers = servers };
var config = new { mcpServers = servers };

await File.WriteAllTextAsync(inspectorResource.ConfigPath, System.Text.Json.JsonSerializer.Serialize(config), ct);
});

return resource
await File.WriteAllTextAsync(inspectorResource.ConfigPath, System.Text.Json.JsonSerializer.Serialize(config), ct);
})
.WithEnvironment(ctx =>
{
if (ctx.Resource is not McpInspectorResource resource)
{
return;
}

var clientEndpoint = resource.GetEndpoint(McpInspectorResource.ClientEndpointName);
var serverProxyEndpoint = resource.GetEndpoint(McpInspectorResource.ServerProxyEndpointName);

Expand All @@ -81,26 +79,7 @@ public static IResourceBuilder<McpInspectorResource> AddMcpInspector(this IDistr
ctx.EnvironmentVariables["CLIENT_PORT"] = clientEndpoint.TargetPort?.ToString() ?? throw new InvalidOperationException("The MCP Inspector 'client' endpoint must have a target port defined.");
ctx.EnvironmentVariables["SERVER_PORT"] = serverProxyEndpoint.TargetPort?.ToString() ?? throw new InvalidOperationException("The MCP Inspector 'server-proxy' endpoint must have a target port defined.");
})
.WithArgs(ctx =>
{
McpInspectorResource inspectorResource = resource.Resource;
McpServerMetadata? defaultMcpServer = inspectorResource.DefaultMcpServer;
if ((defaultMcpServer is null && inspectorResource.McpServers.Count > 0) || (defaultMcpServer is not null && inspectorResource.McpServers.Count == 0))
{
throw new InvalidOperationException("No default MCP server has been configured for the MCP Inspector resource, yet servers have been provided.");
}


if (defaultMcpServer is null && inspectorResource.McpServers.Count == 0)
{
return;
}

ctx.Args.Add("--config");
ctx.Args.Add(inspectorResource.ConfigPath);
ctx.Args.Add("--server");
ctx.Args.Add(defaultMcpServer?.Name ?? throw new InvalidOperationException("The MCP Inspector resource must have a default MCP server defined."));
});
.WithDefaultArgs();
}

/// <summary>
Expand All @@ -125,4 +104,29 @@ public static IResourceBuilder<McpInspectorResource> WithMcpServer<TResource>(
builder.Resource.AddMcpServer(mcpServer.Resource, isDefault, transportType);
return builder;
}

private static IResourceBuilder<McpInspectorResource> WithDefaultArgs(this IResourceBuilder<McpInspectorResource> builder)
{
return builder
.WithArgs(ctx =>
{
McpInspectorResource inspectorResource = builder.Resource;
McpServerMetadata? defaultMcpServer = inspectorResource.DefaultMcpServer;
if ((defaultMcpServer is null && inspectorResource.McpServers.Count > 0) || (defaultMcpServer is not null && inspectorResource.McpServers.Count == 0))
{
throw new InvalidOperationException("No default MCP server has been configured for the MCP Inspector resource, yet servers have been provided.");
}


if (defaultMcpServer is null && inspectorResource.McpServers.Count == 0)
{
return;
}

ctx.Args.Add("--config");
ctx.Args.Add(inspectorResource.ConfigPath);
ctx.Args.Add("--server");
ctx.Args.Add(defaultMcpServer?.Name ?? throw new InvalidOperationException("The MCP Inspector resource must have a default MCP server defined."));
});
}
}
27 changes: 0 additions & 27 deletions ...tyToolkit.Aspire.Hosting.McpInspector.Tests/McpInspectorResourceBuilderExtensionsTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,33 +4,6 @@ namespace CommunityToolkit.Aspire.Hosting.McpInspector.Tests;

public class McpInspectorResourceBuilderExtensionsTests
{
[Fact]
public void AddMcpInspectorWithDefaultsAddsResource()
{
// Arrange
var appBuilder = DistributedApplication.CreateBuilder();

// Act
var inspector = appBuilder.AddMcpInspector("inspector");

using var app = appBuilder.Build();

// Assert
var appModel = app.Services.GetRequiredService<DistributedApplicationModel>();

var inspectorResource = Assert.Single(appModel.Resources.OfType<McpInspectorResource>());
Assert.Equal("inspector", inspectorResource.Name);

var endpoints = inspectorResource.Annotations.OfType<EndpointAnnotation>();
Assert.Equal(2, endpoints.Count());

Assert.Single(endpoints, e => e.Name == "client");
Assert.Single(endpoints, e => e.Name == "server-proxy");

var annotations = inspector.Resource.Annotations;
Assert.Contains(ManifestPublishingCallbackAnnotation.Ignore, annotations);
}

[Fact]
public void WithMcpServerAddsServerToResource()
{
Expand Down
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