Can't access service running in docker

Question

I'm unable to access a nodejs based service via http://localhost:8000 running in a docker image. I'm using Docker for Mac (https://docs.docker.com/docker-for-mac/)

I'm following the tutorial here https://nodejs.org/en/docs/guides/nodejs-docker-webapp/.

The server runs on port 8000. I start the docker image with the following:

$ docker run -p 8000:8000 -d geuis/node-server:latest

If I run docker ps I see:

CONTAINER ID        IMAGE                      COMMAND             CREATED             STATUS              PORTS                    NAMES
9fa2e446918b        geuis/node-server:latest   "npm start"         6 seconds ago       Up 5 seconds        0.0.0.0:8000->8000/tcp   unruffled_lewin

If I docker exec -it 9fa2e446918b /bin/bash I can access the docker vm and I can curl http://localhost:8000 and access the server from inside the container.

However, I try the same curl http://localhost:8000 from my system terminal and its not accessible.

Not sure what I need to do next.

Answer 1

Try the following listen statement:

app.listen(PORT, '0.0.0.0');

From reading the tutorial you mention it looks like express is listening on localhost. This is fine if you're running locally but inside of a container, localhost is not the same localhost that's outside of the container.

0.0.0.0 is the unspecified IPv4 address and so Express will bind on any IP it can find, which will be the IP that your requests are coming in from outside the container.