这篇文章介绍一下蓝绿部署以及使用nginx如何最简单地模拟一下蓝绿部署的方式

蓝绿部署

蓝绿部署的重点在于如下特点

  • 1. 蓝色版本和绿色版本同时存在
  • 2. 实际运行的环境为蓝或则绿,只能为其中之一,通过开关控制

优点和缺点分析:优点在于它的速度和回滚。而缺点也显而易见。可以快速回滚是因为有两套环境同时存在的缘故,所以复杂度和需要的资源会增多,因为其有两套环境。
另外虽然速度有所提高,但是在实现的过程中,开关的控制,无论多快的切换速度,如果不结合其他的技术,还是无法做到完全无缝切换。

模拟蓝绿部署

接下来我们使用nginx的upstream来简单模拟一下蓝绿部署的场景。具体场景如下, 当前活跃的是蓝色版本,通过调整nginx设定,将绿色版本设定为当前活跃版本。

使用nginx模拟进行蓝绿部署的方式

事前准备

事前在7001/7002两个端口分别启动两个服务,用于显示不同信息,为了演示方便,使用tornado做了一个镜像,通过docker容器启动时传递的参数不同用于显示服务的不同。

docker run -d -p 7001:8080 liumiaocn/tornado:latest python /usr/local/bin/daemon.py "Hello blue/green service: v1 in 7001"
docker run -d -p 7002:8080 liumiaocn/tornado:latest python /usr/local/bin/daemon.py "Hello blue/green service: v2 in 7002"

执行日志

[root@kong ~]# docker run -d -p 7001:8080 liumiaocn/tornado:latest python /usr/local/bin/daemon.py "Hello blue/green service: v1 in 7001"
70c74dc8e43d5635983f7240deb63a3fc0599d5474454c3bc5197aa5c0017348
[root@kong ~]# docker run -d -p 7002:8080 liumiaocn/tornado:latest python /usr/local/bin/daemon.py "Hello blue/green service: v2 in 7002"
6c5c2ea322d4ac17b90feefb96e3194ec8adecedaa4c944419316a2e4bf07117
[root@kong ~]# curl http://192.168.163.117:7001
Hello, Service :Hello blue/green service: v1 in 7001
[root@kong ~]# curl http://192.168.163.117:7002
Hello, Service :Hello blue/green service: v2 in 7002
[root@kong ~]#

启动nginx

[root@kong ~]# docker run -p 9080:80 --name nginx-blue-green -d nginx
d3b7098c44890c15918dc47616b67e5e0eb0da7a443eac266dbf26d55049216a
[root@kong ~]# docker ps |grep nginx-blue-green
d3b7098c4489    nginx           "nginx -g 'daemon ..."  10 seconds ago    Up 9 seconds    0.0.0.0:9080->80/tcp   nginx-blue-green
[root@kong ~]#

nginx代码段

准备如下nginx代码段将其添加到nginx的/etc/nginx/conf.d/default.conf中, 模拟方式很简单,通过down来表示流量为零(nginx中无法将weight设置为零),开始的时候100%的流量都发到蓝色版本。

http {
upstream nginx_blug_green {
  server 192.168.163.117:7001 weight=100;
  server 192.168.163.117:7002 down;
}
server {
  listen    80;
  server_name www.liumiao.cn 192.168.163.117;
  location / {
    proxy_pass http://nginx_blug_green;
  }
}

修改default.conf的方法

可以通过在容器中安装vim达到效果,也可以在本地修改然后通过docker cp传入,或者直接sed修改都可。如果在容器中安装vim,使用如下方式即可

[root@kong ~]# docker exec -it nginx-lb sh
# apt-get update
...省略
# apt-get install vim
...省略

修改前

# cat default.conf
server {
  listen    80;
  server_name localhost;
  #charset koi8-r;
  #access_log /var/log/nginx/host.access.log main;
  location / {
    root  /usr/share/nginx/html;
    index index.html index.htm;
  }
  #error_page 404       /404.html;
  # redirect server error pages to the static page /50x.html
  #
  error_page  500 502 503 504 /50x.html;
  location = /50x.html {
    root  /usr/share/nginx/html;
  }
  # proxy the PHP scripts to Apache listening on 127.0.0.1:80
  #
  #location ~ \.php$ {
  #  proxy_pass  http://127.0.0.1;
  #}
  # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
  #
  #location ~ \.php$ {
  #  root      html;
  #  fastcgi_pass  127.0.0.1:9000;
  #  fastcgi_index index.php;
  #  fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name;
  #  include    fastcgi_params;
  #}
  # deny access to .htaccess files, if Apache's document root
  # concurs with nginx's one
  #
  #location ~ /\.ht {
  #  deny all;
  #}
}
#

修改后

# cat default.conf
upstream nginx_blug_green {
  server 192.168.163.117:7001 weight=100;
  server 192.168.163.117:7002 down;
}
server {
  listen    80;
  server_name www.liumiao.cn 192.168.163.117;
  #charset koi8-r;
  #access_log /var/log/nginx/host.access.log main;
  location / {
    #root  /usr/share/nginx/html;
    #index index.html index.htm;
    proxy_pass http://nginx_blug_green;
  }
  #error_page 404       /404.html;
  # redirect server error pages to the static page /50x.html
  #
  error_page  500 502 503 504 /50x.html;
  location = /50x.html {
    root  /usr/share/nginx/html;
  }
  # proxy the PHP scripts to Apache listening on 127.0.0.1:80
  #
  #location ~ \.php$ {
  #  proxy_pass  http://127.0.0.1;
  #}
  # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
  #
  #location ~ \.php$ {
  #  root      html;
  #  fastcgi_pass  127.0.0.1:9000;
  #  fastcgi_index index.php;
  #  fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name;
  #  include    fastcgi_params;
  #}
  # deny access to .htaccess files, if Apache's document root
  # concurs with nginx's one
  #
  #location ~ /\.ht {
  #  deny all;
  #}
}
#

重新加载nginx设定

# nginx -s reload
2018/05/28 04:39:47 [notice] 321#321: signal process started
#

确认结果

10次调用全部输出的都是v1 in 7001

[root@kong ~]# cnt=0; while [ $cnt -lt 10 ]
> do
> curl http://localhost:9080
> let cnt++
> done
Hello, Service :Hello blue/green service: v1 in 7001
Hello, Service :Hello blue/green service: v1 in 7001
Hello, Service :Hello blue/green service: v1 in 7001
Hello, Service :Hello blue/green service: v1 in 7001
Hello, Service :Hello blue/green service: v1 in 7001
Hello, Service :Hello blue/green service: v1 in 7001
Hello, Service :Hello blue/green service: v1 in 7001
Hello, Service :Hello blue/green service: v1 in 7001
Hello, Service :Hello blue/green service: v1 in 7001
Hello, Service :Hello blue/green service: v1 in 7001
[root@kong ~]#

蓝绿部署:切换到绿色版本

通过调整default.conf的weight,然后执行nginx -s reload的方式,在不停止nginx服务的方式下可动态的切换到绿色版本,目标将会将全部的流量都输出v2 in 7002

修改default.conf的方法

只需要将upstream中的server的权重做如下调整:

upstream nginx_blug_green {
  server 192.168.163.117:7001 down;
  server 192.168.163.117:7002 weight=100;
}

重新加载nginx设定

# nginx -s reload
2018/05/28 05:01:28 [notice] 330#330: signal process started
#

确认结果

[root@kong ~]# cnt=0; while [ $cnt -lt 10 ]; do curl http://localhost:9080; let cnt++; done
Hello, Service :Hello blue/green service: v2 in 7002
Hello, Service :Hello blue/green service: v2 in 7002
Hello, Service :Hello blue/green service: v2 in 7002
Hello, Service :Hello blue/green service: v2 in 7002
Hello, Service :Hello blue/green service: v2 in 7002
Hello, Service :Hello blue/green service: v2 in 7002
Hello, Service :Hello blue/green service: v2 in 7002
Hello, Service :Hello blue/green service: v2 in 7002
Hello, Service :Hello blue/green service: v2 in 7002
Hello, Service :Hello blue/green service: v2 in 7002
[root@kong ~]#

总结

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