Spin up your docker environment, then run the following:
$ docker build -t my/kemaltest .
$ docker run -p 8080:8080 -it my/kemaltest
Run the following inside the container, and then hit the docker machine's IP on port 8080 in a browser. You should see a "Hello World" message.
/app # ./test
If you do, CTRL-C
to stop kemal, then run again. Repeat, and eventually you should see the following error:
[production] Kemal is ready to lead at http://0.0.0.0:8080
accept: Invalid argument (Errno)
0x560bb97ebf75: run at /usr/lib/crystal/src/io/file_descriptor.cr 297:7
0x560bb978c606: main at /app/lib/kemal/src/kemal.cr 19:5
0x7f12462c8964: trap at /usr/lib/crystal/src/pointer.cr 129:6