Varnish后端主机的健康状态检查

author：JevonWei
版权声明：原创作品

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配置后端主机的Health Check

环境

Varnish      192.168.198.139
图片服务端    192.168.198.120
程序服务端    192.168.198.128

程序服务器

[root@danran ~]# vim /var/www/html/.healthchk.html
ok

图片服务器

[root@centos6 ~]# vim /data/web/image2/.healthchk.html
oK
[root@centos6 ~]# vim /data/web/images/.healthchk.html
ok

Vernish

[root@danran ~]# vim /etc/varnish/default.vcl
    导入directors模块
    import directors;

    定义健康检查的机制，自定义为healthchk
    probe healthchk {
        .url = "/.healthchk.html";\检查的url为.healthchk.html
        .timeout = 2s;  \超时时间为2s
        .interval = 2s;\检查间隔时间
        .window = 8; \基于最近8次的检查判断
        .threshold = 5; \检查最近8次若有5次成功即为健康状态
    }

    定义一个app程序后端服务器
    backend appsrv1 {
        .host = "192.168.198.128";
        .port = "80";
        .probe = healthchk; \调用健康检查的机制
    }

    定义两个图片服务端
    backend imgsrv1 {
        .host = "192.168.198.120";
        .port = "80";
        .probe = healthchk; \调用健康检查的机制
    }
    backend imgsrv2 {
        .host = "192.168.198.120";
        .port = "8080";
        .probe = healthchk; \调用健康检查的机制
    }

    定义一个图片服务器组imgsrvs，并将imgsrv1和imgsrv2两个后端图片服务器添加进imgsrvs组中
    sub vcl_init {
        new imgsrvs =  directors.round_robin();  \指定调度算法为轮询
        imgsrvs.add_backend(imgsrv1);
        imgsrvs.add_backend(imgsrv2);
    }
    
    sub vcl_recv {
        if (req.url ~ "(?i).(jpg|jpeg|png|gif|svg|txt)$") {
            set req.backend_hint = imgsrvs.backend();
        } else {
            set req.backend_hint = appsrv1;
        }
    }
[root@danran ~]# varnish_reload_vcl    \重新加载/etc/varnish/default.vcl参数文件

Varnish查看后端主机的健康状态

[root@danran ~]# varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082 
backend.list
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8 \Healthy为健康状态，检测了8次，8次成功
imgsrv1(192.168.198.120,,80)   7      probe      Healthy 8/8
imgsrv2(192.168.198.120,,8080) 6      probe      Healthy 8/8

图片服务端故障了一台服务器

添加一条防火墙规则，禁止8080端口的连接，即等同于imgsrv2服务器的故障
[root@centos6 ~]# iptables -A INPUT -p tcp --dport 8080 -j REJECT  

Varnish查看后端主机的健康状态

[root@danran ~]# varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082 
backend.list
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      probe      Healthy 8/8
imgsrv2(192.168.198.120,,8080) 6      probe      Sick 0/8  \检查80次，0次成功，即imgsrv2服务端故障，从而imgsrv2不可用

修复使imgsrv2上线后，imgsrv2恢复正常状态 
[root@danran ~]# varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082 
backend.list
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      probe      Healthy 8/8
imgsrv2(192.168.198.120,,8080) 6      probe      Sick 4/8  \Sick为失败状态
backend.list
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      probe      Healthy 8/8
imgsrv2(192.168.198.120,,8080) 6      probe      Healthy 5/8 \当检查次数大于等于5次时，即表示该服务端可以正常使用

Varnish手动使某后台服务端下线，即修改服务器健康状态为sick

[root@Varnish ~]# varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082
backend.set_health imgsrv1 sick
200 \将imgsrv1服务器的状态手动修改为sick故障状态      

backend.set_healtlist
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      sick       Healthy 8/8 \imgsrv1状态为sick故障状态
imgsrv2(192.168.198.120,,8080) 6      probe      Healthy 8/8

将手动修改为sick状态的后台服务器端上线，即将状态修改为health

[root@Varnish ~]# varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082

backend.set_health imgsrv1 healthy
200 \将imgsrv1服务器的状态手动修改为healthy健康状态，即不管物理后台服务器端是否正常，varnish检测结果都为正常

backend.set_healtlist
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      sick       Healthy 8/8 \imgsrv1状态为sick故障状态
imgsrv2(192.168.198.120,,8080) 6      probe      Healthy 8/8

backend.set_healtlist
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      healthy    Healthy 8/8
imgsrv2(192.168.198.120,,8080) 6      probe      Healthy 8/8

imgsrv1后台服务器端故障，不能正常使用

[root@imgsrv1 ~]# iptables -A INPUT -p tcp --dport 80 -j REJECT 

Varnish检测后端服务器的健康状态

[root@Varnish ~]# varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082

backend.list
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      healthy    Sick 0/8
imgsrv2(192.168.198.120,,8080) 6      probe      Healthy 8/8

将手动修改为sick状态的后台服务器端上线，即将状态修改为health

[root@Varnish ~]# varnishadm -S /etc/varnish/secret -T

backend.set_healtlist
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      sick       Healthy 8/8 \imgsrv1状态为sick故障状态
imgsrv2(192.168.198.120,,8080) 6      probe      Healthy 8/8

backend.set_health imgsrv1 auto
200        

backend.set_healtlist
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      probe      Healthy 8/8
imgsrv2(192.168.198.120,,8080) 6      probe      Healthy 8/8  

imgsrv1后台服务器端故障，不能正常使用

[root@imgsrv1 ~]# iptables -A INPUT -p tcp --dport 80 -j REJECT 

Varnish检测后端服务器的健康状态

[root@Varnish ~]# varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082

backend.set_healtlist
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      probe      Sick 0/8
imgsrv2(192.168.198.120,,8080) 6      probe      Healthy 8/8

修复imgsrv1，使imgsrv1上线1

[root@Varnish ~]# varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082

backend.set_healtlist
200        
Backend name                   Refs   Admin      Probe
appsrv1(192.168.198.128,,80)   7      probe      Healthy 8/8
imgsrv1(192.168.198.120,,80)   7      probe      Healthy 8/8
imgsrv2(192.168.198.120,,8080) 6      probe      Healthy 8/8