* Make sure generated password is random
Use /dev/urandom to get a 32 char password
* Make sure generated password is random
Use /dev/urandom to generate 32 char password
* Make sure generated password is random
1. Use `apk -U --no-cache add` instead of `apk update` + `apk add` +
manually cache clean up.
2. Separate package installation and user, group setup, the combination
to reduce a docker image layer didn't bring benefits here, only makes
Dockerfiles more complex.