Passing custom environment variables

[jonmach]

Hi,

I've configured mcp-proxy as an sse endpoint calling a local stdio service (inside a docker container) to allow for remote deployment of a service.

What I would like to do is to pass custom variables to the stdio service (e.g. GITHUB_TOKEN, USER_ID) etc.

I've written my CMD as follows

CMD ["mcp-proxy", "--pass-environment", "--host=0.0.0.0", "--debug", "--port=8080", "node", "/home/app/mystdio-service/index.js"]

Unfortunately, this means that everyone gets the same experience, and the only alternative I have is to run multiple containers.

Is there any way to pass say the contents of the "env" section in the sse configuration, so that behaviour would be different for different users using the same service?

...
"env": {
    "GITHUB_TOKEN": "my personal github token"
}
...

I tried using the --pass-environment flag, but it didn't seem to have any effect. I.e., it was ignored by the stdio service

The debug trace shows no evidence of the environment variables being passed through the proxy. All I'm seeing is content being returned in the debug, but not content being sent by the client.

Am I missing something?

[sparfenyuk]

Hey @jonmach, with this change #79 it became possible starting from version v0.8.1. Please, check it out and let me know if there're any other problems.

[jonmach]

Ah thank you for coming back on this(@sparfenyuk.

It seems that I was using a standard build ('npm install -g mcp-proxy'), which comes back with a version of 5.3.0 (very different format). It looks to be the same behaviour, so may be a fork I was using without being aware of it. Lesson learned.

I'll aim to do a local build in the container, see how that goes, and let you know the results.

[jonmach]

Thanks Sergey,

But I cannot get this working. I can see the code code in change #79, and it looks to do exactly what I need - pass variables through the env key.

I tried installation via uv (uv tool install mcp-proxy) as well as a build (uv tool install git+https://github.com/sparfenyuk/mcp-proxy).

Is there any way of seeing what variables are being passed in the logs? From a security perspective, perhaps just the keys and not the values could be shown.

Maybe it's my cline config which isn't working, but I'd like to find the root cause.

I also can't work out what version it is. There doesn't seem to be a --version option in the cli itself.

Any thoughts?

[sparfenyuk]

Good point, will add such an argument #93

To ensure that the latest version is installed, use the command uv tool install git+https://github.com/sparfenyuk/mcp-proxy --reinstall.

In addition, this repo has no affiliation with mcp-proxy in npmjs.org

[sparfenyuk]

Integrated into the main branch. Upgrade from the source code and give it a try mcp-proxy --version.

[jonmach]

Thanks Sergey,

--version works well (0.8.2). Despite using --reinstall, it makes no difference. I didn't think it would since this is a container create from an empty machine, but worth trying anyway.

Any chance we could provide some visibility of passed ENV variable names to an SSE endpoint as part of the debug output?