This article will describe how to enable apk community repository. emacs package is in apk community repository.
1 Enable apk community repository
By default, community repository is comment out.
$ cat /etc/apk/repositories #/media/cdrom/apks http://mirror.xtom.com.hk/alpine/v3.8/main #http://mirror.xtom.com.hk/alpine/v3.8/community #http://mirror.xtom.com.hk/alpine/edge/main #http://mirror.xtom.com.hk/alpine/edge/community #http://mirror.xtom.com.hk/alpine/edge/testing
Delete comment out and enable community repository.
$ sudo sed -e 's;^#http\(.*\)/v3.8/community;http\1/v3.8/community;g' \
-i /etc/apk/repositories
$ sudo apk update
2 Install emacs from apk community repository
After enabling apk community repository, emacs can be installed by apk add.
$ sudo apk add emacs