引子
在测试和生产环境中，都会用自己的私有镜像仓库，需要测试pull和push的性能，所以需要准备大量的docker镜像。本文的目的就是解决如何自动化大批量生成docker镜像。
用busybox基础镜像
用busybox作为基础镜像，使用dd命令附加大小不等的层，来批量生成docker镜像。
#!/bin/bash
if [ $# -lt 1 ]
then
echo "Usage: $0 Number TotalSize"
echo "Number: The number of image"
echo "TotalSize: Total storage size which image will be consumed"
exit -1
fi
echo "Image num:$1M"
echo "Total storage size: $2M"
#Average size every images
avg=$(($2/$1))
for((i = 1; i <= $1; i++))
do
docker ps -f name=perfimages$1|grep perfimages$i
if [ $? -eq 0 ];then
docker stop perfimages$i
docker rm perfimages$i
fi
s=$(($RANDOM%$avg+10))
echo $s
docker run --name perfimages$i busybox /bin/sh -c "dd if=/dev/zero of=test.file bs=1M count=$s"
docker commit perfimages$i 172.30.247.186:5000/perfimages$i:latest
docker rm perfimages$i
done
使用红帽的s2i工具
s2i工具可以把git仓库里的源代码直接生成docker镜像。不同语言开发的代码使用不同的基础镜像，下面这个例子是一个ruby的例子。她使用的基础镜像里已经有了ruby语言的工具集。
关于s2i的原理，可以参考openshift的相关文档
#!/bin/bash
# Usage
if [ $# -lt 1 ]
then
echo "Usage: $0 Number TotalSize"
echo "Number: The number of image"
echo "TotalSize: Total storage size which image will be consumed"
exit -1
fi
echo "Image num:$1M"
echo "Total storage size: $2M"
# Average size every images
avg=$(($2/$1))
# S2I produces ready-to-run images by injecting source code into a Docker container
for((i = 1; i <= $1; i++))
do
docker ps -f name=rubycontainer$1|grep rubycontainer$i
if [ $? -eq 0 ];then
docker stop rubycontainer$i
docker rm rubycontainer$i
fi
s=$(($RANDOM%$avg+10))
echo $s
docker run --name rubycontainer$i centos/ruby-23-centos7 /bin/sh -c "dd if=/dev/zero of=test.file bs=1M count=$s"
docker commit rubycontainer$i rubyimages$i:latest
docker rm rubycontainer$i
s2i build https://github.com/openshift/ruby-hello-world rubyimages$i 172.30.247.186:5000/perfimages$i --loglevel 5
docker rmi rubyimages$i
docker push 192.168.100.186:5000/perfimages$i
done