Dockerfile cleanup

Layer cnosolidate & remove unnecessary build packages
Shrinks image from 865MB to 370MB
Exec gunicorn in entrypoint so <ctrl> c works properly
Run as unpriviledged user instead of root

Dockerfile

@@ -1,40 +1,57 @@
 FROM ubuntu:16.04
+
 MAINTAINER Armada Team
 
+ENV DEBIAN_FRONTEND noninteractive
+ENV LIBGIT_VERSION 0.25.0
+
+COPY . /armada
+
+RUN apt-get update && \
+    apt-get upgrade -y && \
+    apt-get install -y --no-install-recommends \
+      netbase \
+      python-all \
+      python-pip \
+      python-setuptools && \
+    apt-get install -y \
+      build-essential \
+      cmake \
+      curl \
+      git \
+      libffi-dev \
+      python-all-dev && \
+    useradd -u 1000 -g users -d /armada armada && \
+    \
+    curl -sSL https://github.com/libgit2/libgit2/archive/v$LIBGIT_VERSION.tar.gz \
+      | tar zx -C /tmp && \
+    cd /tmp/libgit2-$LIBGIT_VERSION && \
+    cmake . && \
+    cmake --build . --target install && \
+    ldconfig && \
+    \
+    cd /armada && \
+    pip install --upgrade pip && \
+    pip install -r requirements.txt pygit2==$LIBGIT_VERSION && \
+    pip install . && \
+    \
+    apt-get purge --auto-remove -y \
+      build-essential \
+      cmake \
+      curl \
+      git \
+      libffi-dev \
+      python-all-dev && \
+    apt-get clean -y && \
+    rm -rf \
+      /root/.cache \
+      /tmp/libgit2-$LIBGIT_VERSION \
+      /var/lib/apt/lists/*
+
 EXPOSE 8000
 
+USER armada
+WORKDIR /armada
+
 ENTRYPOINT ["./entrypoint.sh"]
-
 CMD ["server"]
-
-ENV \
-    LIBGIT_VERSION=0.25.0 \
-    USER=armada
-
-RUN apt-get update -y && \
-    apt-get install -y --no-install-recommends \
-        build-essential \
-        gcc \
-        git \
-        git-review \
-        libffi-dev \
-        libgit2-dev \
-        libssl-dev \
-        netbase \
-        python-dev \
-        python-pip \
-        python-virtualenv \
-    && mkdir -p /root/armada/tools
-
-WORKDIR /root/armada
-
-COPY ./tools/libgit2.sh /root/armada/tools
-RUN /root/armada/tools/libgit2.sh
-
-COPY requirements.txt /root/armada
-RUN pip install --upgrade setuptools urllib3 \
-    && pip install -r requirements.txt pygit2==$LIBGIT_VERSION
-
-COPY . /root/armada
-
-RUN pip install -e .

entrypoint.sh

@@ -6,7 +6,7 @@ PORT="8000"
 set -e
 
 if [ "$1" = 'server' ]; then
-    gunicorn server:api -b :$PORT --chdir armada/api
+    exec gunicorn server:api -b :$PORT --chdir armada/api
 fi
 
 if [ "$1" = 'tiller' ] || [ "$1" = 'apply' ]; then