Claude Desktop invokes MCP server docker image twice on startup

[tianzhou]

claude_desktop_config.json

{
  "mcpServers": {
    "dbhub": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "bytebase/dbhub",
        "--transport",
        "stdio",
        "--dsn",
        "postgresql://postgres:postgres@host.docker.internal:5432/postgres?sslmode=disable"
      ]
    }
  }
}

When Claude Desktop starts, it starts the docker image twice:

CONTAINER ID   IMAGE            COMMAND                  CREATED              STATUS              PORTS                                       NAMES
460f37945bcc   bytebase/dbhub   "node dist/index.js …"   About a minute ago   Up About a minute   8080/tcp                                    charming_brown
1426b40ffdb6   bytebase/dbhub   "node dist/index.js …"   About a minute ago   Up About a minute   8080/tcp                                    goofy_chaplygin
271a297fe72a   postgres:15      "docker-entrypoint.s…"   26 hours ago         Up 26 hours         0.0.0.0:5432->5432/tcp, :::5432->5432/tcp   Stackbricks-PG-15-Local-Test-7960b0

This means if I specify the --name dbhub in docker run, the 2nd invocation will fail due to image name conflict.

I know it may not be the best place to report this bug as it seems to be a Claude Desktop bug. But it's on the CUJ when building the MCP server. I did file the bug via the Claude Desktop support link. But the format doesn't allow me to provide detailed info. So I submit here as well.

The repo: https://github.com/bytebase/dbhub/

[dkozlov]

Workaround:

https://github.com/modelcontextprotocol/servers/tree/main/src/filesystem#build

{
  "mcpServers": {
    "filesystem": {
      "command": "bash",
      "args": [
        "-c",
        "docker attach mcp_filesystem || docker run -i --rm --name mcp_filesystem --mount type=bind,src=/home/user/Downloads,dst=/app/projects mcp/filesystem /app/projects"
        ]
    }
  }
}

[pavelanni]

I see the same thing with Claude Desktop, which starts my server twice. In my case, the server starts as a binary (written in Go and compiled). I don't know how to tell Claude Desktop to start it only once. The other client (https://github.com/chrishayuk/mcp-cli) starts it once, as it should.

If anybody has figured out how to fix it, please share.

[jmorrell-cloudflare]

We've run into the same thing working with https://github.com/geelen/mcp-remote/. Claude Desktop initializes the MCP server process twice, causing two different authentication windows to pop up, which is very confusing for the user.

I attempted to use a lockfile so that only one process could perform auth at a time as a workaround, but this resulted in brittle code that we couldn't ship. It would be much better if Claude fixed this issue

[Shchvova]

Just to be clear - this is not specific to docker. This is for every MPC server. If you would try to listen to the socket or something like that - it would fail as well. No idea why claude does it, is that an intent or error, would be nice to have a comment from the devs.

[frijswijk]

Took me the whole day, running windows claude 0.9.0 and have the same issue with starting twice, can't run my MCP server this way. When will it be fixed anthropic?

[Shchvova]

You can code around it quite easily to be honest, not a big deal. Probably a good benchmark that you server isn't that bad that it must run in single instance and can't figure it out. What if you launch several Claude instances?

[caasi]

I also encountered this issue. I guess maybe they want to test if a MCP server can shutdown itself properly.

Anyway my app will open a port but node failed to close it after shutdown. So I have to use kill-port or something similar. It makes my MCP serve a bit more complex.

[olaservo]

Closing since his bug looks like its specific to the Claude app and not the servers themselves.

For Claude Desktop client issues this is the support link: https://support.anthropic.com/en/articles/9015913-how-to-get-support