runtime docker images support py3

doc/RUN_IN_DOCKER.md

@@ -6,6 +6,8 @@
 
 Docker (GPU version requires nvidia-docker to be installed on the GPU machine)
 
+This document takes Python2 as an example to show how to run Paddle Serving in docker. You can also use Python3 to run related commands by replacing `python` with `python3`.
+
 ## CPU
 
 ### Get docker image

doc/RUN_IN_DOCKER_CN.md

@@ -6,6 +6,8 @@
 
 Docker（GPU版本需要在GPU机器上安装nvidia-docker）
 
+该文档以Python2为例展示如何在Docker中运行Paddle Serving，您也可以通过将`python`更换成`python3`来用Python3运行相关命令。
+
 ## CPU版本
 
 ### 获取镜像

tools/Dockerfile

@@ -3,6 +3,7 @@ FROM centos:7.3.1611
 RUN yum -y install wget && \
     yum -y install epel-release && yum -y install patchelf && \
     yum -y install gcc make python-devel && \
+    yum -y install python3 python3-devel && \
     yum clean all && \
     curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py && \
     python get-pip.py && rm get-pip.py

tools/Dockerfile.gpu

@@ -6,6 +6,7 @@ RUN yum -y install wget && \
     yum -y install libSM-1.2.2-2.el7.x86_64 --setopt=protected_multilib=false && \
     yum -y install libXrender-0.9.10-1.el7.x86_64 --setopt=protected_multilib=false && \
     yum -y install libXext-1.3.3-3.el7.x86_64 --setopt=protected_multilib=false && \
+    yum -y install python3 python3-devel && \
     yum clean all && \
     curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py && \
     python get-pip.py && rm get-pip.py && \