This is Bower as an Alpine Linux package.
See the releases page for the latest download links.
The current installation method for these packages is to pull them in using
wget or curl and install the local file with apk:
apk --no-cache add ca-certificates wget
wget -q -O /etc/apk/keys/sgerrand.rsa.pub https://raw.githubusercontent.com/sgerrand/alpine-pkg-node-bower/master/sgerrand.rsa.pub
wget https://github.com/sgerrand/alpine-pkg-node-bower/releases/download/1.8.0-r0/node-bower-1.8.2-r0.apk
apk add --no-cache node-bower-1.8.2-r0.apk