Monitors
A monitor issues health monitor requests at regular intervals to evaluate the health of each server within an origin pool.
When a pool becomes unhealthy, your load balancer takes that pool out of the server rotation.
Health monitor requests that result in a status change for an origin server are recorded as events in the Load Balancing event logs.
Properties
For an up-to-date list of monitor properties, refer to Monitor properties in our API documentation.
Create monitors
For step-by-step guidance, refer to Create monitors.
Health monitor regions
When you attach a monitor to a pool, you can select multiple regions to increase reporting accuracy.
For each option selected in a pool’s Health Monitor Regions, Cloudflare sends health monitor requests from three separate data centers in that region.
If the majority of data centers for that region pass the health monitor requests, that region is considered healthy. If the majority of regions is healthy, then the origin itself will be considered healthy.
Configurations
All Data Centers (Enterprise only)
Health monitor probes are sent from every single data center in Cloudflare’s network to the origins within the associated pool. This allows probes to hit each origin during intervals set by the customer.
All Regions
Three health monitor probes per region are sent to each origin in the associated pool. There are a total of 13 regions, resulting in 39 probes.
Regional
Three health monitor probes are sent from each specified region within the pool configuration.
Host header prioritization
The host headers used on health monitor requests can be configured either on the monitor itself or on the origins within an origin pool.
When a host header is specified both on the monitor and on the origin, the host header configured on the origin takes precedence over the host header configured on the monitor.
When no host header is specified, Cloudflare uses the Origin Address configured on the origins as the host header for the health monitor requests.
For more details, refer to Override HTTP Host headers.
API commands
The Cloudflare API supports the following commands for monitors. Examples are given for user-level endpoint but apply to the account-level endpoint as well.
| Command | Method | Endpoint |
|---|---|---|
| Create Monitor | POST | accounts/:account_id/load_balancers/monitors |
| Delete Monitor | DELETE | accounts/:account_id/load_balancers/monitors/:id |
| List Monitors | GET | accounts/:account_id/load_balancers/monitors |
| Monitor Details | GET | accounts/:account_id/load_balancers/monitors/:id |
| Overwrite specific properties | PATCH | accounts/:account_id/load_balancers/monitors/:id |
| Overwrite existing monitor | PUT | accounts/:account_id/load_balancers/monitors/:id |
| Preview Monitor | POST | accounts/:account_id/load_balancers/monitors/:id/preview |
Supported protocols
Cloudflare Load Balancing supports public monitoring for HTTP, HTTPS, TCP, UDP, ICMP, ICMP ping, and SMTP.
Load Balancing also supports private monitoring for HTTP, HTTPS, and TCP.