haproxy & keepalived

HA

detect

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# virtual machine will return 'kvm' or 'vmware', physical machine will return 'none'
systemd-detect-virt
# KVM may have not previlege to config vip, so may could not config vip in keepalived

install

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sudo apt install haproxy keepalived  # Debian/Ubuntu
# or
sudo yum install haproxy keepalived  # RHEL/CentOS/Rocky Linux

assume there are two server e.g. 10.225.10.50 and 10.225.10.51, and each bootstrap web service with 13307 port

and i want export both service by same port 13308 with same ip

if server is physical machine, could use haproxy & keepalived strategy

if server is virtural machine, could use

haproxy

both server all should config and bootstrap haproxy

config

/etc/haproxy/haproxy.cfg

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defaults
    mode                    tcp
    log                     global
    option                  tcplog
    option                  dontlognull
		......
		
frontend ft_executor
    bind *:13308
    mode tcp
    default_backend bk_executor

backend bk_executor
    mode tcp
    balance roundrobin
    server executor1 10.225.10.50:13307 check
    server executor2 10.225.10.51:13307 check

bootstrap

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sudo setenforce 0
sudo systemctl enable haproxy
sudo systemctl start haproxy

keepalived

both server all should config and bootstrap keepalived

config

/etc/keepalived/keepalived.conf

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global_defs {
    vrrp_skip_check_adv_addr
    # ⚠️ Remove or comment out vrrp_strict if it exists
    # vrrp_strict
    .......
}

vrrp_script chk_haproxy {
    script "pidof haproxy"
    interval 2
    weight -15
    fall 3
    rise 2
}

vrrp_instance VI_1 {
    state MASTER 					# server1 is MASTER , server2 should be BACKUP
    interface eth0 				# replace eth0 with your real network interface
    virtual_router_id 51
    priority 110 					# server1 is 110, server2 should be lower 
    advert_int 1
    
    # Add unicast configuration, ⚠️ server2 would swap ip , src should be 51, peer should be 50
    unicast_src_ip 10.225.10.50    	# This server's IP
    unicast_peer {
        10.225.10.51                # Peer server's IP
    }
    
    # Add this line to allow traffic to VIP
    accept
    
    authentication {
        auth_type PASS
        auth_pass dingo   # custome password
    }

		# 如果虚拟机无权限配置vip，需要注释掉vip的配置
    #virtual_ipaddress {
    #    10.225.10.160/24 dev eth0 label eth0:vip
    #}
    
    track_script {
        chk_haproxy
    }
}

config virtual ip as 10.225.10.160

bootstrap

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sudo systemctl enable keepalived
sudo systemctl start keepalived