HAPROXY Lab (CentOS VM)

PROXY: A server that intermediates requests and responses between a client and a server.

Types of PROXY

• Forward Proxy: Located between the client and the internet.

• Reverse Proxy: Located between the internet and the server.

Key Features

• Security and Encryption: Protects communication between client and server.

• Caching: Caches responses from the server to the client to improve performance.

• Load Balancing: Distributes traffic across multiple servers to reduce load.

Load Balancing

• L4 Load Balancing: Distributes traffic at the network layer.

• L7 Load Balancing: Distributes traffic at the application layer.

Load Balancing Algorithms

• Round Robin: Distributes requests sequentially across servers.

• Weighted Round Robin: Distributes requests based on server weights.

• IP Hashing: Distributes requests based on client IP hash.

• Least Connections: Distributes requests to the server with the fewest active connections.

• Least Response Time: Distributes requests to the server with the fastest response time.

PRACTICE

1. Server Setup

• Run four virtual machines: VM1, VM2, VM3, VM4

• VM1: HAProxy server

• VM2, VM3, VM4: Apache server

2. Verify and Install Required Files

• Start Virtual Machines

  • Start VM1, VM2, VM3, VM4

• VM2, VM3, VM4: Verify and install Apache server

    systemctl status httpd
    yum -y install httpd
  

• VM1: Verify and install HAProxy server

    yum -y install haproxy
    systemctl status haproxy
  

• VM1, VM2, VM3, VM4: Configure Firewall

    firewall-cmd --list-all
    systemctl start firewalld
    firewall-cmd --add-service=http
    firewall-cmd --add-port=80/tcp --zone=public
    firewall-cmd --add-port=5000/tcp --zone=public
    firewall-cmd --reload
  

3. Start and Configure Apache Web Server

• VM2, VM3, VM4: Start Apache web server

    systemctl start httpd
  

• Write Server Identification Script

  • VM2

      vi /var/www/html/index.html
    

      <h1> Apache Server 01 </h1>
      <link href="style.css" rel="stylesheet" type="text/css" media="screen" />
    

  • VM3

      bash코드 복사vi /var/www/html/index.html
    

      <h1> Apache Server 02 </h1>
      <link href="style.css" rel="stylesheet" type="text/css" media="screen" />
    

  • VM4

      vi /var/www/html/style.css
    

      h1 { color: #471d4f; font-size: 300%; }
    

• Restart Apache Servers

    bash코드 복사systemctl restart httpd
  

5. Configure HAProxy on Server 1

• Edit HAProxy Configuration File

  • Configuration file location: /etc/haproxy/haproxy.cfg

    vi /etc/haproxy/haproxy.cfg

• Default Section

    defaults
        log     global
        mode    http
        option  httplog
        option  dontlognull
        timeout connect 5000
        timeout client  50000
        timeout server  50000
        errorfile 400 /etc/haproxy/errors/400.http
        errorfile 403 /etc/haproxy/errors/403.http
        errorfile 408 /etc/haproxy/errors/408.http
        errorfile 500 /etc/haproxy/errors/500.http
        errorfile 502 /etc/haproxy/errors/502.http
        errorfile 503 /etc/haproxy/errors/503.http
        errorfile 504 /etc/haproxy/errors/504.http
  

• Frontend Section

    frontend http_front
        bind *:5000
        default_backend http_back
  

• Backend Section

    backend http_back
        balance roundrobin
        server server1 192.168.56.101:80 check
        server server2 192.168.56.102:80 check
        server server3 192.168.56.103:80 check
  

• Restart HAProxy

    systemctl restart haproxy
  

6. Load Balancing Configuration (haproxy.cfg)

• Frontend and Backend Configuration

    frontend main
        bind *:5000
        acl url_static path_beg /static /images /javascript /stylesheets
        acl url_static path_end .jpg .gif .png .css .js
        use_backend static if url_static
        default_backend app
  
    backend static
        balance roundrobin
        server static 192.168.56.103:80 check
  
    backend app
        balance roundrobin
        server server1 192.168.56.101:80 check
        server server2 192.168.56.102:80 check
  

• Frontend Section:

  • *bind :5000: Accept connections on port 5000.

  • acl url_static path_beg /static /images /javascript /stylesheets: Match URL paths beginning with /static, /images, /javascript, /stylesheets.

  • acl url_static path_end .jpg .gif .png .css .js: Match URL paths ending with .jpg, .gif, .png, .css, .js.

  • use_backend static if url_static: Use the static backend if the url_static ACL matches.

  • default_backend app: Use the app backend by default.

• Backend Section:

  • backend static:

    • balance roundrobin: Use round robin algorithm to distribute traffic.

    • server static 192.168.56.103:80 check: Use server at 192.168.56.103 with health checks.

  • backend app:

    • balance roundrobin: Use round robin algorithm to distribute traffic.

    • server server1 192.168.56.101:80 check: Use server at 192.168.56.101 with health checks.

    • server server2 192.168.56.102:80 check: Use server at 192.168.56.102 with health checks.

• Restart HAProxy

    systemctl restart haproxy
  

• Verify in Browser

  • Access http://192.168.0.119:5000

  • Observe round robin distribution by refreshing the page

7. Viewing HAProxy Logs

• Open Port 9000

    firewall-cmd --add-port=9000/tcp --zone=public
    systemctl restart firewalld
  

• Add Monitoring Configuration

    listen stats
        bind *:9000
        stats enable
        stats uri /
        stats auth admin:admin
  

• Restart HAProxy

    systemctl restart haproxy
  

• Check Logs

  • Access http://192.168.0.119:9000

8. Changing Load Balancing Algorithm

• Change to leastconn Algorithm

    backend app
        balance leastconn
        server server1 192.168.56.101:80 check
        server server2 192.168.56.102:80 check
  

• Restart HAProxy

    systemctl restart haproxy
  

9. Implementing L4 Load Balancing

• Add Configuration

    frontend tcp_front
        bind *:80
        mode tcp
        default_backend tcp_back
  
    backend tcp_back
        balance roundrobin
        server server1 192.168.56.101:80 check
        server server2 192.168.56.102:80 check
  

• Restart HAProxy

    systemctl restart haproxy
  

• Result

  • Accessing http://192.168.0.119:80 will connect through the HAProxy server, even if the Apache server is not running on VM1.