update docker build and install

Dockerfile

 FROM ubuntu:16.04
 
+# install python and conda
 RUN apt-get update && apt-get install -y python3 git wget bzip2
-
 RUN wget https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh && \
      bash Miniconda3-latest-Linux-x86_64.sh -b
-
 ENV PATH /root/miniconda3/bin:$PATH
 
-RUN git clone https://github.com/mli/gluon-tutorials-zh && \
-    cd gluon-tutorials-zh && \
-    conda env create -f environment.yml
+# install deps
+COPY environment.yml /
+RUN conda env create -f environment.yml
 
+# source activate need bash
 RUN rm /bin/sh && ln -s /bin/bash /bin/sh
 
+# setup notedown
 RUN source activate gluon && \
     mkdir notebook && \
     jupyter notebook --allow-root --generate-config && \
@@ -20,5 +21,12 @@ RUN source activate gluon && \
 
 EXPOSE 8888
 
+# copy notebooks
+RUN  mkdir /gluon-tutorials-zh
+COPY / /gluon-tutorials-zh/
+
+# sanity check
+RUN source activate gluon && notedown --run /gluon-tutorials-zh/chapter01_crashcourse/ndarray.md
+
 CMD source activate gluon && cd /gluon-tutorials-zh && \
     jupyter notebook --ip=0.0.0.0 --allow-root

chapter00_preface/install.md

@@ -38,9 +38,17 @@ jupyter notebook
 
 ## 通过docker安装
 
-首先你需要下载并安装[docker](https://docs.docker.com/engine/installation/)，然后运行下面命令即可
+首先你需要下载并安装[docker](https://docs.docker.com/engine/installation/)。例如Linux下可以
 
+```bash
+wget -qO- https://get.docker.com/ | sh
+sudo usermod -aG docker
+# 然后logout一次
 ```
+
+然后运行下面命令即可
+
+```bash
 docker run -p 8888:8888 muli/gluon-tutorials-zh
 ```