HAProxy Cheat Sheet

Configuration syntax for HAProxy frontends, backends, load-balancing algorithms, and health checks in high-availability setups.

2 PagesAdvancedFeb 10, 2026

Frontend & Backend

Route HTTP traffic to a pool of backend servers.

haproxy

frontend http_front    bind *:80    default_backend http_backbackend http_back    balance roundrobin    option httpchk GET /healthz    server web1 10.0.0.1:3000 check    server web2 10.0.0.2:3000 check    server web3 10.0.0.3:3000 check backup

SSL Termination

Terminate TLS at HAProxy and forward plaintext to backends.

haproxy

frontend https_front    bind *:443 ssl crt /etc/haproxy/certs/example.pem    mode http    redirect scheme https code 301 if !{ ssl_fc }    default_backend http_backfrontend http_redirect    bind *:80    redirect scheme https code 301

Load-Balancing Algorithms

Common 'balance' directive values.

roundrobin- Cycles requests evenly across servers; default and simplest choice
leastconn- Sends new requests to the server with fewest active connections; good for long-lived connections
source- Hashes client IP so the same client consistently hits the same server (sticky by IP)
uri- Hashes the request URI, useful for cache-friendly routing
static-rr- Round robin with weights fixed at start (no dynamic reweighing)
first- Sends to the first server with available capacity, keeping others idle until needed

Stats Page & ACLs

Expose the built-in dashboard and route by path.

haproxy

listen stats    bind *:8404    stats enable    stats uri /stats    stats refresh 10sfrontend http_front    bind *:80    acl is_api path_beg /api    use_backend api_back if is_api    default_backend web_back

Pro Tip

Use 'option httpchk' with a dedicated lightweight health endpoint rather than checking '/', so backend health reflects application readiness, not just whether the web server process is alive.

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