⚖️
Networking & Server

HAProxy

High availability load balancer and reverse proxy for TCP/HTTP traffic

🐧 Linux🍎 Mac🪟 Windows📋 Quick reference →
Reviewed: Tested on: Kubernetes 1.29 · Terraform 1.8 · Ubuntu 22.04

What is this?

HAProxy spreads incoming web traffic across multiple servers so no single server gets overloaded.

📁

Config files for HAProxy

Where to create or edit the main configuration — paths below match the setup steps.

  • /etc/haproxy/haproxy.cfg

    Location: HAProxy server

    Frontends, backends, ACLs, and SSL

📥

Step 01

Install HAProxy

(01)Install HAProxy

Linux
1# Ubuntu / Debian
2sudo apt-get install -y haproxy
3 
4# RHEL / Fedora
5sudo dnf install -y haproxy
6 
7sudo systemctl enable haproxy
⚙️

Step 02

Configure HAProxy

(01)HTTP load balancing

Linux
1sudo nano /etc/haproxy/haproxy.cfg
2 
3# global / defaults sections first, then:
4 
5frontend http_front
6    bind *:80
7    default_backend http_back
8 
9backend http_back
10    balance roundrobin
11    server web1 192.168.1.21:80 check
12    server web2 192.168.1.22:80 check
13 
14# Stats page (optional):
15listen stats
16    bind *:8404
17    stats enable
18    stats uri /stats
19    stats refresh 10s
20 
21sudo haproxy -c -f /etc/haproxy/haproxy.cfg
22sudo systemctl restart haproxy

(02)HTTPS / SSL termination

Linux
1frontend https_front
2    bind *:443 ssl crt /etc/haproxy/certs/example.com.pem
3    default_backend http_back
4 
5# Combine cert + key:
6# cat cert.pem key.pem > example.com.pem

(03)TCP (Layer 4) load balancing

Linux
1frontend mysql_front
2    bind *:3306
3    mode tcp
4    default_backend mysql_back
5 
6backend mysql_back
7    mode tcp
8    balance leastconn
9    server db1 192.168.1.31:3306 check
10    server db2 192.168.1.32:3306 check
✅

Step 03

Verify HAProxy

(01)Check status

Linux
1sudo systemctl status haproxy
2curl http://localhost/stats
3sudo ss -tlnp | grep haproxy
⚡

Step 04

Manage HAProxy

(01)Reload without downtime

Linux
1sudo haproxy -c -f /etc/haproxy/haproxy.cfg
2sudo systemctl reload haproxy
3echo "show stat" | sudo socat stdio /run/haproxy/admin.sock

📋Config templates

1 YAML template for HAProxy. Copy and deploy after setup.

1 ready-to-copy template. Expand one, copy the YAML, then run the deploy commands.

deployment.yml

yaml
1apiVersion: apps/v1
2kind: Deployment
3metadata:
4  name: web
5spec:
6  replicas: 3
7  selector:
8    matchLabels:
9      app: web
10  template:
11    metadata:
12      labels:
13        app: web
14    spec:
15      containers:
16        - name: nginx
17          image: nginx:alpine
18          ports:
19            - containerPort: 80

service-loadbalancer.yml

LoadBalancer assigns external IP (cloud) or MetalLB IP

yaml
1apiVersion: v1
2kind: Service
3metadata:
4  name: web-lb
5spec:
6  type: LoadBalancer
7  selector:
8    app: web
9  ports:
10    - port: 80
11      targetPort: 80
12      protocol: TCP
📄

Step 01

Apply LoadBalancer

(01)Deploy to cluster

Linux
1kubectl apply -f .
2kubectl get all
3kubectl get pods -w

(02)Remove

Linux
1kubectl delete -f .