**Summary**
To send health check probes to a port other than the one to which normal traffic is sent, add the port argument. In the following example, the health check is sent to port 8080.
```
backend servers
server srv1 10.0.0.1:80 check port 8080
server srv2 10.0.0.2:80 check port 8080
```
**Use case**
Sometimes the main application service (port 80/443) is only healthy if other internal components are also up. Running a dedicated health check endpoint on a different port (e.g., 8080) ensures HAProxy LB probes check application readiness, not just whether TCP/HTTP accepts connections.
Example Use Case:
Imagine a web application with the following design:
Port 80 (frontend): Handles user HTTP requests.
Port 8080 (health check endpoint): Exposes /healthz or /ready for monitoring.
It only returns 200 OK if the database and cache are reachable and the app is fully initialized.
If the DB or cache goes down, /healthz returns 500, but port 80 might still respond (with errors).
**Additional information**
https://www.haproxy.com/documentation/haproxy-configuration-tutorials/reliability/health-checks/#tcp-health-checks
Consider the CLI option:
```
set load-balancing haproxy backend bk01 server srv01 check-port xxx
```
or
```
```
set load-balancing haproxy backend bk01 server srv01 check port xxx
```
```