My first little foray into rust, which is generally useless and presumably reflects my naivete when it comes to developing in rust. The async fibber is an example threaded socket server that does fibonacci stuff via TCP on port 1234 (yeah I hardcoded the port) and via HTTP on port 8080 with a janky REST API (POST JSON to it to get direction).
Since I've been working with OpenShift so much recently, I baked it up as an openshift "microservice", statically compiled into a container where it is the only occupant, and is built as a single layer. The container image weighs in at under 2MB, but of course would be larger depending on the size of the app baked in. The fibber itself is about 12kB of code, so presumably the rest is all of the statically linked stuff that gets shoved into the bin by rustc.
For fun, here's what tar -tvf has to say about the container layer
when exported as a tar file:
-rwxr-xr-x root/root 0 2020-06-04 10:10 .dockerenv
-rwxr-xr-x root/root 3230848 2020-06-03 14:15 asyncfibber
drwxr-xr-x root/root 0 2020-06-04 10:10 dev/
-rwxr-xr-x root/root 0 2020-06-04 10:10 dev/console
drwxr-xr-x root/root 0 2020-06-04 10:10 dev/pts/
drwxr-xr-x root/root 0 2020-06-04 10:10 dev/shm/
drwxr-xr-x root/root 0 2020-06-04 10:10 etc/
-rwxr-xr-x root/root 0 2020-06-04 10:10 etc/hostname
-rwxr-xr-x root/root 0 2020-06-04 10:10 etc/hosts
lrwxrwxrwx root/root 0 2020-06-04 10:10 etc/mtab -> /proc/mounts
-rwxr-xr-x root/root 0 2020-06-04 10:10 etc/resolv.conf
drwxr-xr-x root/root 0 2020-06-04 10:10 proc/
drwxr-xr-x root/root 0 2020-06-04 10:10 sys/
So as far as a "microservice" goes, it's pretty micro.
Templates for building and running this thing in openshift can be found in the ocp_templates dir.
Assuming docker, though this should work just as well with podman,
docker build -t asyncfibber ., and then docker run -P asyncfibber.
Find the exposed port with docker ps, then you can talk to it over a
tcp socket (using telnet, netcat/nc, socat, a program you wrote, whatever)
to get some fibonacci numbers.
The socket interface is:
- Send an int, followed by a newline
- Send whatever you want, but don't expect a good answer
You will receive back either:
Ok: <the answer>Err: <an error message explaining what happened or berating you>
The http interface is:
- Send JSON, looking like '{"n": }'
- Send whatever you want, but don't expect a good answer
You will receive back either:
{"ok": <the answer>}{"err": <an error message explaining what happened or berating you>}- An HTTP 400 Bad Request response
I haven't spent any time with docker trying to figure out how to easily
stop it from the shell. pkill -9 asyncfibber works great, though, if
you don't mind being rude to all the asyncfibbers that you might be
running.