remove some dependencies

docker/Dockerfile.gce

@@ -5,22 +5,10 @@ ENV PACKAGES="\
     gcc \
     make \
     bash \
-    shadow \
     libffi-dev \
     musl-dev \
     openssl-dev \
-    py-pip \
-    python \
     python-dev \
-    linux-headers \
-    sudo \
-    rsync \
-    curl \
-    ruby \
-    ruby-dev \
-    ruby-etc \
-    ruby-rdoc \
-    ruby-irb \
     git \
     openssh-client \
 "
@@ -32,10 +20,6 @@ ENV PIP_PACKAGES="\
     pycrypto \
 "
 
-ENV GEM_PACKAGES="\
-    rubocop \
-"
-
 RUN \
     apk update \
     && apk add --update --no-cache ${PACKAGES} \
@@ -44,8 +28,7 @@ RUN \
     && pip install --no-cache-dir ${PIP_PACKAGES} \
     && rm -rf /root/.cache \
     && mkdir /root/.ssh \
-    && chmod 700 /root/.ssh \
-    && gem install ${GEM_PACKAGES}
+    && chmod 700 /root/.ssh
 
 USER root
 ENV SHELL /bin/bash