Localhost unreachable in Docker mode

Things run fine locally, but doing backstop test --docker fails with errors trying to reach my server running on my host. I’m using a Mac for my primary machine, but I’m also seeing similar issues on my Ubuntu desktop. Here are different values I tried for localhost:

url	error
http://localhost:3000	ENGINE ERROR: net::ERR_CONNECTION_REFUSED at http://localhost:3000
http://127.0.0.1:3000	ENGINE ERROR: net::ERR_CONNECTION_REFUSED at http://127.0.0.1:3000
http://10.0.0.215:3000 (my actual IP)	Works!
http://host.docker.internal:3000/	ENGINE ERROR: net::ERR_NAME_NOT_RESOLVED at http://host.docker.internal:3000/

As you can see, the only way I can get it to work is by looking up my IP and embedding it in the scenario url, which isn’t portable.

I’m running a simple hello world server using the hello-world-server npm package.

Any ideas what’s going on?

[yebrahim]

In case anyone else hits this, this worked for me on my Mac: http://docker.for.mac.host.internal, although I’ll have to detect the OS in the script so I can switch between this and something that works on Ubuntu. Closing this since no action required.

[andyrichardson]

I’ve had a similar issue on Linux when using 127.0.0.1 as the hostname.

Exposing the container to the host network has resolved the issue. PR incoming.