Docker镜像构建的四种优化方式
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2022-03-30 07:52:47
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镜像构建的优化
###删除之间的所有的test：v*镜像和容器（参考上一篇Docker容器的安装配置，以及 Dockerfile 的使用方法）###
[aaa@qq.com docker]# docker rmi -f test:v3
Untagged: test:v3 ## 删除镜像用rmi，删除容器用rm
[aaa@qq.com docker]# docker rm -f vm1
vm1
[aaa@qq.com docker]# docker rm -f vm2
vm2
[aaa@qq.com docker]# docker rm -f vm3
vm3
构建nginx镜像
busybox满足不了nginx的构建需求，所以我们下载rehl7的镜像：
[aaa@qq.com ~]# docker load -i rhel7.tar
e1f5733f050b: Loading layer [==================================================>] 147.1MB/147.1MB
[aaa@qq.com ~]# cd docker/
[aaa@qq.com docker]# vim Dockerfile
FROM rhel7 # 镜像来自rhel7
EXPOSE 80 # 开放80端口
MAINTAINER aaa@qq.com # 维护联系人
COPY dvd.repo /etc/yum.repos.d/ # 配置yum源
RUN rpmdb --rebuilddb # 重新构建rpm数据库，不然会报错
RUN yum install -y gcc make pcre-devel zlib-devel # 安装依赖性
ADD nginx-1.18.0.tar.gz /mnt/ # 复制nginx到/mnt并解压
WORKDIR /mnt/nginx-1.18.0 # 进入到/mnt/nginx-1.18.0
RUN ./configure --prefix=/usr/local/nginx # 预安装
RUN make
RUN make install # 编译安装
ENTRYPOINT ["/usr/local/nginx/sbin/nginx","-g","dameon off;"] # 开启nginx
[aaa@qq.com docker]# cp /etc/yum.repos.d/westos.repo ./dvd.repo # 建立yum源
[aaa@qq.com docker]# ls
Dockerfile dvd.repo nginx-1.18.0.tar.gz testfile
[aaa@qq.com docker]# docker build -t nginx:v1 . 进行构建
## 这里我们可以看到dockerfie里面的各个步骤
Step 1/12 : FROM rhel7
---> 0a3eb3fde7fd
Step 2/12 : EXPOSE 80
---> Using cache
---> d08b343a793d
Step 3/12 : MAINTAINER aaa@qq.com
---> Using cache
---> 017f4b147a32
Step 4/12 : COPY dvd.repo /etc/yum.repos.d/
---> Using cache
---> f5d2b9218060
Step 5/12 : RUN rpmdb --rebuilddb
---> Running in 163a4532bf45
Removing intermediate container 163a4532bf45
---> c0387a3e3e69
Step 6/12 : RUN yum install -y gcc make pcre-devel zlib-devel
---> Running in e2d387cdc0b9
Step 7/12 : ADD nginx-1.18.0.tar.gz /mnt/
---> 000ce03c7c4e
Step 8/12 : WORKDIR /mnt/nginx-1.18.0
---> Running in e539b8ed9a67
Removing intermediate container e539b8ed9a67
---> 9ea9d4c3ff3f
Step 9/12 : RUN ./configure --prefix=/usr/local/nginx
---> Running in 261812c201ce
Step 10/12 : RUN make
Step 11/12 : RUN make install
Step 12/12 : ENTRYPOINT ["/usr/local/nginx/sbin/nginx","-g","dameon off;"]
---> Running in 873edc7d9d94
Removing intermediate container 873edc7d9d94
---> 9b7f0c89bf98
Successfully built 9b7f0c89bf98
Successfully tagged nginx:v1
1.清理缓存，清理中间产物
[aaa@qq.com docker]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
nginx v1 9b7f0c89bf98 3 minutes ago 303MB
## 他现在有303M 是比较大的
因为我们再yum安装的时候会产生缓存，再 /var/cache/yum/里，
还有解压后的目录 nginx-1.18.0
那我们就可以从这里进行优化。
清理中间产物。
[aaa@qq.com docker]# vim Dockerfile
RUN yum install -y gcc make pcre-devel zlib-devel && yum clean all 清理缓存
RUN rm -fr /mnt/nginx-1.18.0 删除中间产物
[aaa@qq.com docker]# docker build -t nginx:v2 .
[aaa@qq.com docker]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
nginx v2 aa029b13d29a 12 seconds ago 277MB
nginx v1 9b7f0c89bf98 11 minutes ago 303MB
变小了。
2.减少镜像构建层数
[aaa@qq.com docker]# docker history nginx:v2
IMAGE CREATED CREATED BY SIZE COMMENT
aa029b13d29a 2 minutes ago /bin/sh -c #(nop) ENTRYPOINT ["/usr/local/n… 0B
168fc81963e5 2 minutes ago /bin/sh -c rm -fr /mnt/nginx-1.18.0 0B
32531153adcf 2 minutes ago /bin/sh -c make install 3.88MB
afa9d1979fe6 2 minutes ago /bin/sh -c make 12.4MB
d7fb616f785c 3 minutes ago /bin/sh -c ./configure --prefix=/usr/local/n… 71.7kB
1c8cc01a2f4b 3 minutes ago /bin/sh -c #(nop) WORKDIR /mnt/nginx-1.18.0 0B
e7cabc8289c4 3 minutes ago /bin/sh -c #(nop) ADD file:46b14d1c307d23f50… 6.25MB
551102a70245 3 minutes ago /bin/sh -c yum install -y gcc make pcre-deve… 107MB
c0387a3e3e69 15 minutes ago /bin/sh -c rpmdb --rebuilddb 6.64MB
f5d2b9218060 18 minutes ago /bin/sh -c #(nop) COPY file:2b3dce3b05892ae2… 76B
017f4b147a32 18 minutes ago /bin/sh -c #(nop) MAINTAINER aaa@qq.com… 0B
d08b343a793d 18 minutes ago /bin/sh -c #(nop) EXPOSE 80 0B
0a3eb3fde7fd 5 years ago 140MB Imported from -
镜像构建的层数越少，我们的镜像越小。我们当前有12层，我们可以把能放在一起的放在一层去执行。
FROM rhel7
EXPOSE 80
MAINTAINER aaa@qq.com
COPY dvd.repo /etc/yum.repos.d/
ADD nginx-1.18.0.tar.gz /mnt
WORKDIR /mnt/nginx-1.18.0
RUN rpmdb --rebuilddb && yum install -y gcc make pcre-devel zlib-devel && yum clean all && ./configure --prefix=/usr/local/nginx && make && make install && rm -fr /mnt/nginx-1.18.0
ENTRYPOINT ["/usr/local/nginx/sbin/nginx","-g","dameon off;"]
我们将所有的RUN 都放在了一起，然后将 COPY 和ADD 提前。
[aaa@qq.com docker]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
nginx v3 db577ca1f8c7 6 seconds ago 258MB
nginx v2 aa029b13d29a 15 minutes ago 277MB
nginx v1 9b7f0c89bf98 27 minutes ago 303MB
又小了19M.
3.多阶段构建镜像
- 我们构建nginx的最终目的就是得到 /usr/local/nginx/sbin/nginx 这个二进制程序。
我们可以再镜像A中完成构建的过程，再把二进制程序拷贝到B镜像中去，就极大的优化了空间。
FROM rhel7 as build #命名为build
EXPOSE 80
MAINTAINER aaa@qq.com
COPY dvd.repo /etc/yum.repos.d/
ADD nginx-1.18.0.tar.gz /mnt
WORKDIR /mnt/nginx-1.18.0
RUN sed -i 's/CFLAGS="$CFLAGS -g"/#CFLAGS="$CFLAGS -g/g' auto/cc/gcc && rpmdb --rebuilddb && yum install -y gcc make pcre-devel zlib-devel && yum clean all && ./configure --prefix=/usr/local/nginx && make && make install && rm -fr /mnt/nginx-1.18.0
FROM rhel7
EXPOSE 80
MAINTAINER aaa@qq.com
VOLUME ["/usr/local/nginx/html"] #数据卷，这样我们再宿主机上配置发布页面就行。
COPY --from=build /usr/local/nginx /usr/local/nginx # 把上面镜像的目录拷贝到这个镜像的目录中
sed -i ‘s/CFLAGS="$CFLAGS -g"/#CFLAGS="$CFLAGS -g/g’ 是关闭debug。也能减小。
Successfully tagged nginx:v4
[aaa@qq.com docker]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
nginx v4 a68855981d36 6 seconds ago 141MB
<none> <none> 3f21fd924668 8 seconds ago 255MB
nginx v3 db577ca1f8c7 20 minutes ago 258MB
nginx v2 aa029b13d29a 35 minutes ago 277MB
nginx v1 9b7f0c89bf98 About an hour ago 303MB
rhel7 latest 0a3eb3fde7fd 5 years ago 140MB
这样就只剩下了141M了。而且我们的nginx是以rhel7为基础镜像的，所以说nginx只有1M的大小。
4.使用更加精简的基础镜像
我们要构建nginx的新镜像，我们就只需要和nginx运行相关的文件，再上面的例子中，rhel7这个基础镜像还是比较大的，它里面的东西我们还是有很多永不上的。
比如：
我们运行apache，就只需要apache的主程序和这些文件就足够了，nginx也相同。
我们导入两个精简的基础镜像：
[aaa@qq.com ~]# docker load -i distroless.tar
668afdbd4462: Loading layer [==================================================>] 18.39MB/18.39MB
Loaded image: gcr.io/distroless/base:latest
[aaa@qq.com ~]# docker load -i nginx.tar
014cf8bfcb2d: Loading layer [==================================================>] 58.46MB/58.46MB
832a3ae4ac84: Loading layer [==================================================>] 53.91MB/53.91MB
e89b70d28795: Loading layer [==================================================>] 3.584kB/3.584kB
Loaded image: nginx:latest
[aaa@qq.com ~]# mkdir distroless
[aaa@qq.com ~]# cd distroless/
[aaa@qq.com distroless]# vim Dockerfile
FROM nginx as base
ARG Asia/Shanghai
RUN mkdir -p /opt/var/cache/nginx && \
cp -a --parents /usr/lib/nginx /opt && \
cp -a --parents /usr/share/nginx /opt && \
cp -a --parents /var/log/nginx /opt && \
cp -aL --parents /var/run /opt && \
cp -a --parents /etc/nginx /opt && \
cp -a --parents /etc/passwd /opt && \
cp -a --parents /etc/group /opt && \
cp -a --parents /usr/sbin/nginx /opt && \
cp -a --parents /usr/sbin/nginx-debug /opt && \
cp -a --parents /lib/x86_64-linux-gnu/ld-* /opt && \
cp -a --parents /lib/x86_64-linux-gnu/libpcre.so.* /opt && \
cp -a --parents /lib/x86_64-linux-gnu/libz.so.* /opt && \
cp -a --parents /lib/x86_64-linux-gnu/libc* /opt && \
cp -a --parents /lib/x86_64-linux-gnu/libdl* /opt && \
cp -a --parents /lib/x86_64-linux-gnu/libpthread* /opt && \
cp -a --parents /lib/x86_64-linux-gnu/libcrypt* /opt && \
cp -a --parents /usr/lib/x86_64-linux-gnu/libssl.so.* /opt && \
cp -a --parents /usr/lib/x86_64-linux-gnu/libcrypto.so.* /opt && \
cp /usr/share/zoneinfo/${TIME_ZONE:-ROC} /opt/etc/localtime
FROM gcr.io/distroless/base
COPY --from=base /opt /
EXPOSE 80 443
ENTRYPOINT ["nginx","-g","daemon off;"]
[aaa@qq.com distroless]# docker build -t nginx:v5 .
[aaa@qq.com distroless]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
nginx v5 2e1946a440c2 5 seconds ago 26.8MB
<none> <none> 715d6019c6ad 6 seconds ago 119MB
nginx v4 a68855981d36 About an hour ago 141MB
<none> <none> 3f21fd924668 About an hour ago 255MB
nginx v3 db577ca1f8c7 About an hour ago 258MB
nginx v2 aa029b13d29a 2 hours ago 277MB
nginx v1 9b7f0c89bf98 2 hours ago 303MB
此时就只有26.8M了，所以我们尽量使用精简的基础镜像。
运行：
[aaa@qq.com distroless]# docker run -d --name nginx nginx:v5
40f023d69a69af8912e45dbb5f651dbf33aea67ccf0686f957449e41752963e9
[aaa@qq.com distroless]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
40f023d69a69 nginx:v5 "nginx -g 'daemon of…" 5 seconds ago Up 4 seconds 80/tcp, 443/tcp nginx
[aaa@qq.com distroless]# docker inspect nginx 检查容器
...
"Gateway": "172.17.0.1",
"IPAddress": "172.17.0.2", # 它的ip地址为这个
...
#访问：
[aaa@qq.com distroless]# curl 172.17.0.2
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
width: 35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
这里为什么和本机不再同一ip还可以访问哪？
[aaa@qq.com distroless]# ip a
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 52:54:00:e4:9b:44 brd ff:ff:ff:ff:ff:ff
inet 172.25.254.1/24 brd 172.25.254.255 scope global ens3
valid_lft forever preferred_lft forever
inet6 fe80::5054:ff:fee4:9b44/64 scope link
valid_lft forever preferred_lft forever
3: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
link/ether 02:42:26:3d:ce:55 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0 ## 看到了吧
valid_lft forever preferred_lft forever
inet6 fe80::42:26ff:fe3d:ce55/64 scope link
valid_lft forever preferred_lft forever
9: aaa@qq.com: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default
link/ether a2:c8:79:b7:7b:f3 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet6 fe80::a0c8:79ff:feb7:7bf3/64 scope link
valid_lft forever preferred_lft forever
启动docker之后就会默认添加docker的设备。访问时先通过docker0 再通过本地的回环接口
每开启一个镜像就会多一个veth的网卡设备。，它会桥接到docker0设备上
[aaa@qq.com distroless]# brctl show
bridge name bridge id STP enabled interfaces
docker0 8000.0242263dce55 no veth0df22f1
看到了吧。
此时我们的物理机是访问不了的，因为容器和外界是隔离的，我们也没有做端口映射，所以我们应该将容器的80端口映射到server1的80端口上，这样我们的物理机才能访问。
[aaa@qq.com distroless]# cd
[aaa@qq.com ~]# docker run -d -p 80:80 --name nginx nginx:v5
28c25d9ff5b5ecede72238d94fb315471bf00c47b92b4f89b7972fd674e90cbb
[aaa@qq.com ~]# netstat -tnlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 2992/sshd
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 3103/master
tcp6 0 0 :::80 :::* LISTEN 5414/docker-proxy
tcp6 0 0 :::22 :::* LISTEN 2992/sshd
tcp6 0 0 ::1:25 :::* LISTEN 3103/master
可见80端口打开了，通过docker-proxy
就可以访问了
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