✨ run MCP on Databricks Apps

.gitignore

@@ -124,4 +124,6 @@ gunicorn.conf.py
 # ignore version file
 src/databricks/labs/mcp/_version.py
 
-.ruff_cache/
+.ruff_cache/
+.build/
+.databricks

README.md

@@ -13,6 +13,7 @@ Table of Contents
     - [Usage](#usage)
     - [Supported tools](#supported-tools)
   - [Developer Tools Server](#developer-tools-server)
+  - [Deploying the MCP server on Databricks Apps](#deploying-the-mcp-server-on-databricks-apps)
   - [Support](#support)
   - [Contributing](#contributing)
 
@@ -76,6 +77,24 @@ the following tools:
 
 This server is currently under construction. It is not yet usable, but contributions are welcome!
 
+## Deploying the MCP server on Databricks Apps
+
+This server can be deployed on Databricks Apps. To do so, follow the instructions below:
+1. Move into the project directory:
+```bash
+cd /path/to/this/repo
+```
+
+2. Deploy the app:
+```bash
+databricks bundle deploy -p <name-of-your-profile>
+```
+
+3. Run the app:
+```bash
+databricks bundle run mcp-on-apps -p <name-of-your-profile>
+```
+
 ## Support
 Please note that all projects in the `databrickslabs` GitHub organization are provided for your exploration only, and are not formally supported by Databricks with Service Level Agreements (SLAs).  They are provided AS-IS and we do not make any guarantees of any kind.  Please do not submit a support ticket relating to any issues arising from the use of these projects.
 
@@ -85,3 +104,4 @@ Any issues discovered through the use of this project should be filed as GitHub
 
 We welcome contributions :) - see [CONTRIBUTING.md](./CONTRIBUTING.md) for details. Please make sure to read this guide before 
 submitting pull requests, to ensure your contribution has the best chance of being accepted.
+

databricks.yml

@@ -0,0 +1,26 @@
+bundle:
+  name: mcp-on-apps
+
+sync:
+  include:
+    - .build
+
+artifacts:
+  default:
+    type: whl
+    path: .
+    build: uv build --wheel
+
+resources:
+  apps:
+    mcp-on-apps:
+      name: "mcp-on-apps"
+      description: "MCP Server on Databricks Apps"
+      source_code_path: ./.build
+      config:
+        command: ["unitycatalog-mcp-app"]
+
+targets:
+  dev:
+    mode: development
+    default: true

hooks/apps_build.py

@@ -0,0 +1,49 @@
+from typing import Any
+from hatchling.builders.hooks.plugin.interface import BuildHookInterface
+from pathlib import Path
+import shutil
+
+
+class AppsBuildHook(BuildHookInterface):
+    """Hook to create a Databricks Apps-compatible build.
+
+    This hook is used to create a Databricks Apps-compatible build of the project.
+
+    The following steps are performed:
+    - Remove the ./.build folder if it exists.
+    - Copy the artifact_path to the ./.build folder.
+    - Write the name of the artifact to a requirements.txt file in the ./.build folder.
+    - The resulting build directory is printed to the console.
+
+    """
+
+    def finalize(
+        self, version: str, build_data: dict[str, Any], artifact_path: str
+    ) -> None:
+        self.app.display_info(
+            f"Running Databricks Apps build hook for project {self.metadata.name} in directory {Path.cwd()}"
+        )
+        # remove the ./.build folder if it exists
+        build_dir = Path(".build")
+        self.app.display_info(f"Resulting build directory: {build_dir.absolute()}")
+
+        if build_dir.exists():
+            self.app.display_info(f"Removing {build_dir}")
+            shutil.rmtree(build_dir)
+            self.app.display_info(f"Removed {build_dir}")
+        else:
+            self.app.display_info(f"{build_dir} does not exist, skipping removal")
+
+        # copy the artifact_path to the ./.build folder
+        build_dir.mkdir(exist_ok=True)
+        self.app.display_info(f"Copying {artifact_path} to {build_dir}")
+        shutil.copy(artifact_path, build_dir)
+
+        # write the name of the artifact to a requirements.txt file in the ./.build folder
+        requirements_file = build_dir / "requirements.txt"
+
+        requirements_file.write_text(Path(artifact_path).name, encoding="utf-8")
+
+        self.app.display_info(
+            f"Apps-compatible build written to {build_dir.absolute()}"
+        )

pyproject.toml

@@ -24,10 +24,15 @@ dev-dependencies = [
     "ruff>=0.9.4",
     "pytest>=8.3.4",
     "isort>=6.0.1",
+    "hatchling>=1.27.0",
 ]
 
+[tool.hatch.build.hooks.custom]
+path = "hooks/apps_build.py"
+
 [project.scripts]
 unitycatalog-mcp = "databricks.labs.mcp.servers.unity_catalog:main"
+unitycatalog-mcp-app = "databricks.labs.mcp.servers.unity_catalog.app:start_app"
 
 [build-system]
 requires = ["hatchling", "hatch-fancy-pypi-readme", "hatch-vcs"]

src/databricks/labs/mcp/servers/unity_catalog/app.py

@@ -0,0 +1,65 @@
+from mcp.server import NotificationOptions, Server
+from mcp.types import Tool as ToolSpec
+from mcp.server.sse import SseServerTransport
+import uvicorn
+from databricks.labs.mcp.servers.unity_catalog.tools import (
+    Content,
+)
+from starlette.applications import Starlette
+from starlette.routing import Mount, Route
+from databricks.labs.mcp.servers.unity_catalog.cli import get_settings
+
+from databricks.labs.mcp._version import __version__ as VERSION
+from databricks.labs.mcp.servers.unity_catalog.server import get_tools_dict
+
+
+server = Server(name="mcp-unitycatalog", version=VERSION)
+tools_dict = get_tools_dict(settings=get_settings())
+
+
+@server.list_tools()
+async def list_tools() -> list[ToolSpec]:
+    return [tool.tool_spec for tool in tools_dict.values()]
+
+
+@server.call_tool()
+async def call_tool(name: str, arguments: dict) -> list[Content]:
+    tool = tools_dict[name]
+    return tool.execute(**arguments)
+
+
+sse = SseServerTransport("/messages/")
+
+
+# Define handler functions
+async def handle_sse(request):
+    async with sse.connect_sse(
+        request.scope, request.receive, request._send
+    ) as streams:
+        await server.run(
+            streams[0],
+            streams[1],
+            server.create_initialization_options(
+                notification_options=NotificationOptions(
+                    resources_changed=True, tools_changed=True
+                )
+            ),
+        )
+
+
+# Create Starlette routes for SSE and message handling
+routes = [
+    Route("/sse", endpoint=handle_sse),
+    Mount("/messages/", app=sse.handle_post_message),
+]
+
+# Create and run Starlette app
+app = Starlette(routes=routes)
+
+
+def start_app():
+    uvicorn.run(app, host="0.0.0.0", port=8000)
+
+
+if __name__ == "__main__":
+    start_app()