Error adding server from Docker repository #483

Activity

1. simonlpaige commented on May 19, 2026

   

   simonlpaige

   on May 19, 2026

   More actions

   Looking at the error, the issue is clear: MCPProxy is trying to use the docker:// protocol scheme, but Go's HTTP client doesn't natively handle Docker container URLs. The error unsupported protocol scheme "docker" indicates the transport layer is attempting to make an HTTP request to a Docker URL instead of spawning a Docker container.

   This is likely in the pkg/transport or internal/client subsystem where transport strategies are resolved. The no-auth strategy path seems to be falling through to a generic HTTP POST handler instead of recognizing the Docker scheme and launching the container.

   Steps to isolate:

   1. Confirm MCPProxy version (mcpproxy --version)
   2. Check if Docker Desktop/daemon is running and accessible
   3. Try a non-Docker MCP server from the catalog to rule out general connectivity issues
   4. Look at transport.go for the Docker scheme handler - it may be missing or not registered in the transport factory

   Workaround: If you need immediate access to Docker-based MCP servers, you can run them manually via docker run and connect to the exposed port using http://localhost:<port> instead of the Docker registry URL.

   Related code area: The error message pattern suggests the transport layer in internal/transport/http.go or similar - the scheme router likely needs a "docker" case that calls Docker SDK to start the container and get its local address.
2. Dumbris

   closed this as completedin #484on May 20, 2026
3. Dumbris

   added a commit that references this issue on May 20, 2026

   fix(registry/483): Docker MCP Catalog → docker run install (no fake d…

   ...

   f772e49
4. Dumbris commented on May 20, 2026

   

   Dumbris

   on May 20, 2026

   Member

   More actions

   Thank you for pointing this out!

   The fix is available in the latest release: v0.33.1 (via PR #484).

   I tested it end-to-end and it works. One minor inconvenience worth flagging: after adding a server from the Docker MCP Catalog, Docker has to pull the image on first run — and during that window the server is shown as disconnected in the UI. I need to think about how to surface that pull progress better (probably an intermediate image_pulling state with a progress hint).

   I will continue working on broader registry integration improvements — there is a follow-up spec being drafted to modernize the registry layer around the canonical registry.modelcontextprotocol.io v0 schema, so multi-package servers (npm / pypi / oci) get a deterministic install path instead of the current per-registry heuristics.
5. albertovelo commented on May 20, 2026

   

   albertovelo

   on May 20, 2026

   More actions

   @Dumbris confirmed, it's now working for me (on a Mac with Docker Desktop) thank you!
6. Dumbris

   added 3 commits that reference this issue on Jun 1, 2026

   feat(070): registry easy upstream-add — keystone core op + CLI MVP (U…

   ...

   354580f

   fix(registries): versioned User-Agent for Pulse + Fleur stdio not rem…

   ...

   cf12950

   fix(diagnostics): classify stdio exit-before-initialize; surface stde…

   ...

   ebd5136
7. Dumbris

   added a commit that references this issue on Jul 14, 2026

   fix(registries): stop inventing routes on user-added registry URLs, v…

   ...

   9257408