ngx_http_healthcheck_module - polls backends and if they respond with HTTP 200 + an optional request body, they are marked good. Otherwise, they are marked bad.
You can get the module from GitHub
This also gives you access to a health status page that lets you seehow well your healthcheck are doing.
This module is not distributed with the NGINX source. See the installation instructions.
The docs on this wiki can get out of date. For the authoritative information, please see the README file inside the plugin’s git repository
Enables health checking of an upstream
Delay in msec between healthchecks for a single peer.
How many milliseconds a healthcheck is allowed to take place
Number of healthchecks good or bad in a row it takes to switch from down to up and back. Good to prevent flapping
Required directive. What to send for the healthcheck. Each argument is appended by rn and the entire thing is suffixed with another rn. For example,
healthcheck_send 'GET /health HTTP/1.0' 'Host: www.yourhost.com';
You probably want to end your health check with some directive that closes the connection, like Connection: close.
What to expect in the HTTP BODY, (meaning not the headers), in a correct response. If unset, just a HTTP 200 status code is required for a peer
How big a buffer to use for the health check. Remember to include headers PLUS body, not just body.
When inside a /location block, replaced the HTTP body with backend health status. Use similarly to the stub_status module.
This module is not distributed with the NGINX source. You can download the module from here Read the installation instructions inside the README file.