Add scratch as base image

.github/workflows/docker-publish.yml

@@ -40,6 +40,8 @@ jobs:
         - { tag: debian,        base-image: debian,               arch: x86_64-unknown-linux-gnu,  plugin: true  }
         - { tag: glibc-busybox, base-image: 'busybox:glibc',      arch: x86_64-unknown-linux-gnu,  plugin: false }
         - { tag: musl-busybox,  base-image: 'busybox:musl',       arch: x86_64-unknown-linux-musl, plugin: false }
+        - { tag: glibc,         base-image: scratch,              arch: x86_64-unknown-linux-gnu,  plugin: false }
+        - { tag: musl,          base-image: scratch,              arch: x86_64-unknown-linux-musl, plugin: false }
     steps:
     - uses: actions/checkout@v1
     - uses: actions/download-artifact@master

docs/docker.md

@@ -7,6 +7,8 @@
 | `alpine`          | `alpine:latest`      | yes     | apk             | all `nu:musl-busybox` image + libcrypto, libssl, libtls, libz    | ~(3+61) MB  |
 | `musl-busybox`    | `busybox:musl`       | no      | —               | GNU utils + _musl_                                               | ~(1+16) MB  |
 | `glibc-busybox`   | `busybox:glibc`      | no      | —               | GNU utils + _glibc_                                              | ~(3+17) MB  |
+| `glibc`           | `scratch`            | no      | —               | **only `nu` binary-executable** which depend on glibc runtime    | ~17 MB      |
+| `musl`            | `scratch`            | no      | —               | **only `nu` binary-executable** statically linked to musl        | ~16 MB      |
 
 [.slimify-excludes]: https://github.com/debuerreotype/debuerreotype/blob/master/scripts/.slimify-excludes
 [distroless/base]: https://github.com/GoogleContainerTools/distroless/blob/master/base/README.md
@@ -44,6 +46,38 @@ This variant is highly recommended when final image size being as small as possi
 
 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][alpine] for examples of how to install packages if you are unfamiliar).
 
+### `nu:<version>-<libc-variant>`
+This image is based on [`scratch`](https://hub.docker.com/_/scratch) which doesn't create an extra layer. This variants can be handy in a project that uses multiple programming language as you need a lot of tools. By using this in [multi-stage build][], you can slim down the docker image that need to be pulled.
+
+[multi-stage build]: https://docs.docker.com/develop/develop-images/multistage-build/
+
+<details><summary>example</summary>
+
+- using `glibc` variant
+```dockerfile
+FROM nu:0.2-glibc as shell
+FROM node:slim
+
+# Build your plugins
+
+COPY --from=shell /bin/nu /bin/
+# Something else
+ENTRYPOINT ["nu"]
+```
+
+- using `musl` variant
+```dockerfile
+FROM nu:musl as shell
+FROM go:alpine
+
+# Build your plugins
+
+COPY --from=shell /bin/nu /bin/
+# Something else
+ENTRYPOINT ["nu"]
+```
+</details>
+
 ### `nu:<version>-<libc-variant>-busybox`
 This image is based on [Busybox](http://www.busybox.net/) which is a very good ingredient to craft space-efficient distributions. It combines tiny versions of many common UNIX utilities into a single small executable. It also provides replacements for most of the utilities you usually find in GNU fileutils, shellutils, etc. The utilities in BusyBox generally have fewer options than their full-featured GNU cousins; however, the options that are included provide the expected functionality and behave very much like their GNU counterparts. Basically, this image provides a fairly complete environment for any small or embedded system.