From the official docs:
```
Note: The official Debian and Ubuntu images automatically run apt-get clean, so explicit invocation is not required.
```
Also added ` && rm -rf /var/lib/apt/lists/*` as part of the install line which probably does what was intended (no need to make a new layer).
Added apt-get update to the RUN payload, as it should be part of the same layer.
Both are documented here: https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/
FROM debian:jessie
MAINTAINER Erik Dasque <erik@frenchguys.com>
-RUN apt-get update
-RUN apt-get install --no-install-recommends -y build-essential \
+RUN apt-get update && apt-get install --no-install-recommends -y build-essential \
gcc \
unzip \
wget \
gcc-arm-none-eabi \
binutils-arm-none-eabi \
libnewlib-arm-none-eabi \
- git
-
-RUN apt-get clean
-RUN rm -rf /var/lib/apt/lists/*
+ git \
+ && rm -rf /var/lib/apt/lists/*
ENV keyboard=ergodox
ENV subproject=ez