Testing Linux behavior for host.docker.internal
On linux you must use extra_hosts "host.docker.internal:host-gateway"
See: https://stackoverflow.com/a/67158212
The difference between test-1 and test-2 is that test-2 has the extra_hosts definition
$ docker compose run test-1
[+] Building 0.0s (0/0)
[+] Creating 1/0
✔ Container host-docker-internal-web-1 Running 0.0s
[+] Building 0.0s (0/0)
-------
Content of /etc/hosts
-------
127.0.0.1 localhost
::1 localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
172.24.0.3 83c6d6256131
-------
Trying to reach host.docker.internal
-------
curl: (6) Could not resolve host: host.docker.internal
$ docker compose run test-2
[+] Building 0.0s (0/0)
[+] Creating 1/0
✔ Container host-docker-internal-web-1 Running 0.0s
[+] Building 0.0s (0/0)
-------
Content of /etc/hosts
-------
127.0.0.1 localhost
::1 localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
172.17.0.1 host.docker.internal
172.24.0.3 58fcfbafddb3
-------
Trying to reach host.docker.internal
-------
HTTP/1.1 200 OK
Server: nginx/1.25.1
Date: Sun, 18 Jun 2023 18:53:52 GMT
Content-Type: text/html
Content-Length: 615
Last-Modified: Tue, 13 Jun 2023 17:34:28 GMT
Connection: keep-alive
ETag: "6488a8a4-267"
Accept-Ranges: bytes