fix caffe validate in docker

docker/mace-dev-lite/Dockerfile

@@ -85,8 +85,7 @@ RUN cd /opt/ && \
     rm -f android-ndk-r15c-linux-x86_64.zip
 
 ENV ANDROID_NDK_VERSION r15c
-ENV ANDROID_NDK /opt/android-ndk-${ANDROID_NDK_VERSION}
-ENV ANDROID_NDK_HOME ${ANDROID_NDK}
+ENV ANDROID_NDK_HOME /opt/android-ndk-${ANDROID_NDK_VERSION}
 
 # add to PATH
 ENV PATH ${PATH}:${ANDROID_NDK_HOME}
@@ -104,3 +103,7 @@ RUN pip install -i http://pypi.douban.com/simple/ --trusted-host pypi.douban.com
     sh==1.12.14 \
     pycodestyle==2.4.0 \
     filelock
+
+# fix docker in docker error: `error while loading shared libraries: libltdl.so.7`
+# refer to: https://github.com/jenkinsci/docker/issues/506
+RUN apt-get install -y libltdl7

docker/mace-dev/Dockerfile

@@ -44,3 +44,8 @@ RUN cd /opt/ && \
     wget -q https://dl.google.com/android/repository/android-ndk-r16-linux-x86_64.zip && \
     unzip -q android-ndk-r16-linux-x86_64.zip && \
     rm -f android-ndk-r16-linux-x86_64.zip
+## Download other NDK r17b
+RUN cd /opt/ && \
+    wget -q https://dl.google.com/android/repository/android-ndk-r17b-linux-x86_64.zip && \
+    unzip -q android-ndk-r17b-linux-x86_64.zip && \
+    rm -f android-ndk-r17b-linux-x86_64.zip

docs/installation/using_docker.rst

@@ -45,6 +45,8 @@ Create container with the following command
     docker run -it --privileged -d --name mace-dev \
                -v /dev/bus/usb:/dev/bus/usb --net=host \
                -v /local/path:/container/path \
+               -v /usr/bin/docker:/usr/bin/docker \
+               -v /var/run/docker.sock:/var/run/docker.sock \
                registry.cn-hangzhou.aliyuncs.com/xiaomimace/mace-dev-lite
     # Execute an interactive bash shell on the container
     docker exec -it mace-dev /bin/bash