Merge pull request #276 from LaurentGoderre/alpine-docs

Added the alpine docs to the readme

Author: chorrell

README.md

@@ -122,6 +122,32 @@ on their system. It, by design, has a large number of extremely common Debian
 packages. This reduces the number of packages that images that derive from it
 need to install, thus reducing the overall size of all images on your system.
 
+## `node:alpine`
+
+This image is based on the popular
+[Alpine Linux project](http://alpinelinux.org), available in
+[the `alpine` official image](https://hub.docker.com/_/alpine). Alpine Linux is
+much smaller than most distribution base images (~5MB), and thus leads to much
+slimmer images in general.
+
+This variant is highly recommended when final image size being as small as 
+possible is desired. The main caveat to note is that it does use
+[musl libc](http://www.musl-libc.org) instead of
+[glibc and friends](http://www.etalabs.net/compare_libcs.html), so certain
+software might run into issues depending on the depth of their libc
+requirements. However, most software doesn't have an issue with this, so this
+variant is usually a very safe choice. See
+[this Hacker News comment thread](https://news.ycombinator.com/item?id=10782897)
+for more discussion of the issues that might arise and some pro/con comparisons
+of using Alpine-based images.
+
+To minimize image size, it's uncommon for additional related tools
+(such as `git` or `bash`) to be included in Alpine-based images. Using this
+image as a base, add the things you need in your own Dockerfile
+(see the [`alpine` image description](https://hub.docker.com/_/alpine/) for
+examples of how to install packages if you are unfamiliar).
+
+
 ## `node:onbuild`
 
 This image makes building derivative images easier. For most use cases, creating