Docker Healthchecks without curl and wget

I needed to add healthchecks to a container that does not have curl and wget installed.

I found this snippet which uses raw tcp sockets and should work everywhere:

healthcheck:
  test: [ "CMD-SHELL", "exec 3<>/dev/tcp/127.0.0.1/8080;echo -e \"GET /health HTTP/1.1\r\nhost: http://localhost\r\nConnection: close\r\n\r\n\" >&3;grep \"HTTP/1.1 200 OK\" <&3" ]
  interval: 10s
  timeout: 5s
  retries: 5

This loosely translates to this curl command:

curl -f http://localhost:8080/health || exit 1

Source: https://stackoverflow.com/a/76790330 ↗