Install packages in Alpine docker

The equivalent of apt or apt-get in Alpine is apk

A typical Dockerfile will contain, for example:

RUN apk add --no-cache wget

--no-cache is the equivalent to:
apk add wget && rm -rf /var/cache/apk/*

or, before the –no-cache option was available:

RUN apk update && apk add wget

Alpine rm -rf /var/cache/apk/* has the Debian equivalent rm -rf /var/lib/apt/lists/*.

See the Alpine comparison with other distros for more details.