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--- linux_wiki:load_balancing_haproxy_and_keepalived [2017/07/07 22:54]
billdozor [Network Addressing Setup]
+++ linux_wiki:load_balancing_haproxy_and_keepalived [2019/05/25 23:50]
@@ Line 1: / Line 1: @@
-====== Load Balancing with HAProxy And Keepalived ======
-**General Information**
-Creating a highly available pair of load balancers with HAProxy and Keepalived.
-**Checklist**
-  * Number of systems
-    * 2 servers to be load balancers
-    * 2 servers for web servers (in the example)
-  * Distro(s): Enterprise Linux 7
-----
-====== Network Addressing Setup ======
-Network configuration used in the examples below.
-Load Balancers
-  * Server "lb01" -> 10.1.2.1 (eth0)
-  * Server "lb02" -> 10.1.2.2 (eth0)
-  * "lb" -> 10.1.2.3 (load balancer virtual IP - floats between servers)
-Web Servers (used in haproxy example config)
-  * web01 -> 10.1.2.50
-  * web02 -> 10.1.2.51
-----
-====== Install ======
-Install the required packages on the load balancer servers
-  * KeepAliveD (high availability)<code bash>yum install keepalived</code>
-  * HA-Proxy (load balancing)<code bash>yum install haproxy</code>
-----
-====== Configure ======
-Configuring keepalived and haproxy.
-===== Keepalived =====
-Keepalived utlizes a Linux kernel implementation of VRRP. (Virtual Router Redundancy Protocol)
-Official Site: http://www.keepalived.org/
-  * Configure all nodes with these keepalive settings (/etc/keepalived/keepalived.conf). **Example**:<code bash>! Configuration File for keepalived
-vrrp_script check_haproxy {
-  script "killall -0 haproxy"  # check the haproxy process
-  timeout 1
-  interval 2  # every 2 seconds
-  weight 2  # add 2 points if OK
-}
-vrrp_instance VI_1 {
-    state BACKUP  # All instances 'BACKUP' to prevent VIP flapping
-    interface eth0
-    virtual_router_id 51
-    priority 100  # All instances same priority to prevent VIP flapping
-    advert_int 1
-    authentication {
-      auth_type PASS
-      auth_pass PASSWORDHERE
-    }
-    virtual_ipaddress {
-.1.2.3
-    }
-  track_script {
-    check_haproxy
-  }
-}</code>
-===== HA-Proxy =====
-HAProxy is a TCP/HTTP load balancer.
-Official Site: http://www.haproxy.org/
-  * Configure HA-Proxy (/etc/haproxy/haproxy.cfg)
-    * Remove all example frontend and backend config sections (leave default section)
-    * Add New frontend/backend sections **Example**:<code bash>#---------------------------------------------------------------------
-# http-in frontend which proxys to the backends
-#---------------------------------------------------------------------
-frontend  http-in *:80
-    # Log format
-    option httplog
-    #-- ACLs - Match HTTP Requests --#
-    acl url_web       path_beg    -i /mywebsite
-    #-- Backend Selection based on ACLs --#
-    use_backend web_pool1    if url_web
-#---------------------------------------------------------------------
-# Backend Configuration
-#---------------------------------------------------------------------
-backend web_pool1
-    balance  roundrobin
-    server  web01 10.1.2.50:80 check
-    server  web02 10.1.2.51:80 check</code>
-===== Logging =====
-Setup logging for HAProxy.
-  * Create a Rsyslog drop in file for HA-Proxy (/etc/rsyslog.d/haproxy.conf)<code bash>## HA-Proxy Rsyslog Config ##
-# Load UDP Modules
-$ModLoad imudp
-# Run UDP server
-$UDPServerRun 514
-# Allow only localhost
-$AllowedSender UDP, 127.0.0.1
-# Send local2 haproxy logs to /var/log/haproxy.log
-local2.none  /var/log/messages
-local2.*     /var/log/haproxy.log</code>
-  * Restart rsyslog<code bash>systemctl restart rsyslog</code>
-----
-====== Operate ======
-Operating the load balancers.
-----
-===== Services =====
-Start and enable the services on each node.
-  * HA-Proxy<code bash>systemctl start haproxy
-systemctl enable haproxy</code>
-  * Keepalived<code bash>systemctl start keepalived
-systemctl enable keepalived</code>
-----
-===== Reboots =====
-Reboot procedure and dependencies.
-  * Load Balancers (lb01, lb02) can be rebooted 1 at a time to avoid service interruption.
-  * Determine the inactive system (the system that does NOT have the virtual IP as a secondary address<code bash>ip addr sh</code>
-    * Reboot the inactive system<code bash>reboot</code>
-    * Once the inactive system is up, verify keepalived and haproxy are running<code bash>systemctl status keepalived haproxy</code>
-  * Stop keepalived on the active system in order to force a fail over<code bash>systemctl stop keepalived</code>
-    * Reboot the system with keepalived stopped<code bash>reboot</code>
-----