Install python packages from ubuntu's repositories

Also reduces image size by updating, installing and cleaning
packages in one single step

Dockerfile

@@ -9,16 +9,7 @@ ENV SALT_VERSION="2018.3.4" \
     LIBSSH2_VERSION="1.8.0" \
     LIBGIT2_VERSION="0.27.7" \
     PYGIT2_VERSION="0.27.2" \
-    GITPYTHON_VERSION="2.1.11" \
-    M2CRYPTO_VERSION="0.31.0" \
-    MAKO_VERSION="1.0.7" \
-    PYCRYPTODOME_VERSION="3.7.2" \
-    LIBNACL_VERSION="1.6.1" \
-    RAET_VERSION="0.6.8" \
-    CHERRYPY_VERSION="18.0.1" \
-    TIMELIB_VERSION="0.2.4" \
-    DOCKERPY_VERSION="1.10.6" \
-    MSGPACKPURE_VERSION="0.1.3"
+    M2CRYPTO_VERSION="0.31.0"
 
 ENV SALT_DOCKER_DIR="/etc/docker-salt" \
     SALT_ROOT_DIR="/etc/salt" \
@@ -35,24 +26,21 @@ ENV SALT_CONFS_DIR="${SALT_DATA_DIR}/config" \
     SALT_BASE_DIR="${SALT_DATA_DIR}/srv" \
     SALT_LOGS_DIR="${SALT_DATA_DIR}/logs"
 
-# Set non interactive mode
-ENV DEBIAN_FRONTEND=noninteractive
-
 RUN mkdir -p ${SALT_BUILD_DIR}
 WORKDIR ${SALT_BUILD_DIR}
 
 # Install packages
-RUN apt-get update
-RUN apt-get install --yes --quiet --no-install-recommends \
-    sudo ca-certificates wget locales pkg-config openssh-client \
+RUN apt-get update \
+ && DEBIAN_FRONTEND=noninteractive apt-get install --yes --quiet --no-install-recommends \
+    sudo ca-certificates apt-transport-https wget locales pkg-config openssh-client \
     python${PYTHON_VERSION} python${PYTHON_VERSION}-dev \
-    python3-pip python3-setuptools python3-wheel gettext-base \
-    supervisor logrotate
-
-# Configure locales
-RUN update-locale LANG=C.UTF-8 LC_MESSAGES=POSIX \
+    python3-pip python3-setuptools python3-wheel \
+    supervisor logrotate git gettext-base tzdata \
+ && DEBIAN_FRONTEND=noninteractive update-locale LANG=C.UTF-8 LC_MESSAGES=POSIX \
     locale-gen en_US.UTF-8 \
-    dpkg-reconfigure locales
+    dpkg-reconfigure locales \
+ && DEBIAN_FRONTEND=noninteractive apt-get clean --yes \
+ && rm -rf /var/lib/apt/lists/*
 
 # Install saltstack
 COPY assets/build ${SALT_BUILD_DIR}
@@ -67,8 +55,6 @@ COPY assets/runtime ${SALT_RUNTIME_DIR}
 RUN chmod -R +x ${SALT_RUNTIME_DIR}
 
 # Cleaning tasks
-RUN apt-get clean --yes
-RUN rm -rf /var/lib/apt/lists/*
 RUN rm -rf ${SALT_BUILD_DIR}/*
 
 # Entrypoint