Lol well I don't know what the trigger is for pulling in libc there, because I've built massive scale services that did a lot of nontrivial stuff and then the deployment was a single-binary docker container that did not have libc. The only thing needed to be put in the container was a directory full of root certs so it could do TLS.

(full disclosure, I don't think I ever had my service look up the address of localhost)

edit: seems like you probably have CGO_ENABLED=1, which is now the default and will cause simple networking things to use libc. Set CGO_ENABLED=0 and you won't have libc.