How to install .apk on Alpine Linux like .deb in Debian using dpkg

Let's say you are trying to install glibc in Alpine

Download the packages into your current directory

wget "https://circle-artifacts.com/gh/andyshinn/alpine-pkg-glibc/6/artifacts/0/home/ubuntu/alpine-pkg-glibc/packages/x86_64/glibc-2.21-r2.apk"
wget "https://circle-artifacts.com/gh/andyshinn/alpine-pkg-glibc/6/artifacts/0/home/ubuntu/alpine-pkg-glibc/packages/x86_64/glibc-bin-2.21-r2.apk"

Then, use apk with --allow-untrusted flag

apk add --allow-untrusted glibc-2.21-r2.apk glibc-bin-2.21-r2.apk

And finish the installation (only needed in this example)

/usr/glibc/usr/bin/ldconfig /lib /usr/glibc/usr/lib