How to forward a UDP port from a devcontainer?

Question

I'm trying to use the "Node.js & Mongo DB" devcontainer from Microsoft (https://github.com/microsoft/vscode-dev-containers/tree/main/containers/javascript-node-mongo/.devcontainer) with my udp server made in Nodejs.

The problem is as follows: When i try to forward a port in devcontainer.json example : "forwardPorts": [1117].

It seems to only forward 1117/tcp when i actually want to forward 1117/udp.

I'm trying to making this work for this project : https://github.com/QuentinGruber/h1z1-server/blob/master/.devcontainer/devcontainer.json

Answer 1

The documentation is kinda fuzzy regarding protocols used for exposed ports with forwardPorts tag:

forwardPorts

• array
• An array of ports that should be forwarded from inside the container to the local machine.

Because of that I would recommend trying to use the older appPort tag because when I looked here it said they're using the docker-compose syntax which means you can specify the ports and protocol like so:

docker-compose:

ports:
- "3000"
- "8921:5000"

devcontainers.json:

"appPort": [ 3000, "8921:5000" ]

And in your case:

"appPort": [ "1117:1117/udp" ]

According to the docs, using the appPort tag is also useful when you want to access the application (or expose the ports) to more than just localhost