I ran into this while checking connectivity between containers on an internal Docker network where the image had neither curl nor wget.

The main surprise was that Bash has /dev/tcp which lets you do the equivalent of an HTTP request with a bit of shell magic, for instance:

  exec 3<>/dev/tcp/service/8642
  printf 'GET /health HTTP/1.1\r\nHost: service\r\nConnection: close\r\n\r\n' >&3
  cat <&3

Where `service` is just the hostname of whatever you’re talking to and 8642 is the port you are trying to talk HTTP to.

Pretty cool!