restic/rest-server install & configure 

apk add rest-server \
  rest-server-doc # Optional

Set command line params via /etc/conf.d/rest-server

See docs at /usr/share/doc/rest-server/README.md
or from the rest-server github repo: https://github.com/restic/rest-server.

addgroup -S rest-server # adduser -S does not autocreate a group
adduser -S -h /var/lib/rest-server -g "Restic REST server,,," -D rest-server rest-server

Edit /etc/conf.d/rest-server to add

REST_USER=rest-server
REST_GROUP=rest-server

And configure REST_SERVER_PATH and any additional options (REST_SERVER_OPTS)

Enable on start up

rc-update add rest-server

Start it immediately

service rest-server start

To manage the htpasswd file use apache2-utils

apk add apache2-utils
htpasswd …

See Also