[WSL2] Cannot access windows service running on host from a container using `host.docker.internal`

[mgcrea]

Environment

Windows build number: 10.0.19042.572
Your Distribution version: lsb_release: not found
Whether the issue is on WSL 2 and/or WSL 1: Linux version 4.19.128-microsoft-standard (oe-user@oe-host) (gcc version 8.2.0 (GCC)) #1 SMP Tue Jun 23 12:58:10 UTC 2020

It's running on a clean Windows10 install followed by a docker desktop 3.0 setup and a docker-compose up -d.

Steps to reproduce

Start a service on the windows host:

npm i -g http-server
http-server -p8080

Run a container with a bind on host-gateway:

docker run -it --rm --add-host=host.docker.internal:host-gateway alpine

Try to curl the windows host inside (/etc/hosts properly has 192.168.65.1 host.docker.internal):

curl http://host.docker.internal:8080

Expected behavior

Working access according to the WSL docs: Accessing Windows networking apps from Linux (host IP)

So not sure if the docs are outdated (WSL1?) or if I have something misconfigured but this is on a clean install and with Windows Defender turned off.

Actual behavior

/ # curl http://host.docker.internal:8080
curl: (28) Failed to connect to host.docker.internal port 8080: Operation timed out

Does work if I use the vEthernet (WSL) ip (eg. curl http://172.27.64.1:8080), but since it changes at every restart and I haven't found a reliable way to expose this IP address to my container, I'm stuck.

[simonferquel]

You should try without adding the --add-host flag (it is not needed on Desktop). We fixed it lately, but not sure if it is in a public build yet.

[mgcrea]

@simonferquel indeed it does seem to resolve properly without the --add-host as it resolves to another IP and does work!

• Working without, resolving to 192.168.65.2

PS C:\Users\User> docker run -it --rm alpine sh -c "apk add curl; curl -X HEAD -vvv http://host.docker.internal:8080"
fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/community/x86_64/APKINDEX.tar.gz
(1/4) Installing ca-certificates (20191127-r4)
(2/4) Installing nghttp2-libs (1.41.0-r0)
(3/4) Installing libcurl (7.69.1-r3)
(4/4) Installing curl (7.69.1-r3)
Executing busybox-1.31.1-r19.trigger
Executing ca-certificates-20191127-r4.trigger
OK: 7 MiB in 18 packages
Warning: Setting custom HTTP method to HEAD with -X/--request may not work the
Warning: way you want. Consider using -I/--head instead.
*   Trying 192.168.65.2:8080...
* Connected to host.docker.internal (192.168.65.2) port 8080 (#0)
> HEAD / HTTP/1.1
> Host: host.docker.internal:8080
> User-Agent: curl/7.69.1
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< server: ecstatic-3.3.2
< Content-Type: text/html
< etag: W/"562949953516050-0-2020-12-21T11:31:34.262Z"
< last-modified: Mon, 21 Dec 2020 11:31:34 GMT
< cache-control: max-age=3600
< Date: Mon, 21 Dec 2020 17:54:49 GMT
< Connection: keep-alive
< Keep-Alive: timeout=5
* no chunk, no close, no size. Assume close to signal end
<
* Closing connection 0

• Broken using the CLI flag, resolving to 192.168.65.1

PS C:\Users\User> docker run -it --rm --add-host=host.docker.internal:host-gateway alpine sh -c "apk add curl; curl -X HEAD -vvv http://host.docker.internal:8080"
>>
fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/community/x86_64/APKINDEX.tar.gz
(1/4) Installing ca-certificates (20191127-r4)
(2/4) Installing nghttp2-libs (1.41.0-r0)
(3/4) Installing libcurl (7.69.1-r3)
(4/4) Installing curl (7.69.1-r3)
Executing busybox-1.31.1-r19.trigger
Executing ca-certificates-20191127-r4.trigger
OK: 7 MiB in 18 packages
Warning: Setting custom HTTP method to HEAD with -X/--request may not work the
Warning: way you want. Consider using -I/--head instead.
*   Trying 192.168.65.1:8080...
* connect to 192.168.65.1 port 8080 failed: Operation timed out
* Failed to connect to host.docker.internal port 8080: Operation timed out
* Closing connection 0
curl: (28) Failed to connect to host.docker.internal port 8080: Operation timed out

Behavior seems wrong so I'll let that open for now.

[gomrinal]

Hi There,
I am getting the same error!

r = adapter.send(request, **kwargs)
  File "/opt/bitnami/python/lib/python3.8/site-packages/requests/adapters.py", line 516, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='host.docker.internal', port=30002): Max retries exceeded with url: /api/v1/datastore/write (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7fdbccf2e130>: Failed to establish a new connection: [Errno -2] Name or service not known'))
127.0.0.1 - - [18/Feb/2021 03:48:40] "POST /api/v1/user/ HTTP/1.1" 500 -

[microsoft-github-policy-service]

This issue has been automatically closed since it has not had any activity for the past year. If you're still experiencing this issue please re-file this as a new issue or feature request.

Thank you!