healthcheck.conf

#
# NGINX Advanced Healtcheck
# This configuration requires NGINX Plus
#

# Import the javascript code
js_import healthcheck from conf.d/healthcheck.js;

# Log format for healthcheck requests
log_format healthcheck_log '[$time_local] $remote_addr:$remote_port '
        '$server_addr:$server_port '
        '"$request" $status $body_bytes_sent "$http_referer" '
        '"$http_user_agent" "$http_x_forwarded_for"';

# Internal upstream for time-based healthcheck
upstream server_check {
        zone server_check 64k;

        # Servers here must be 127.0.0.1:<port>
        # <port> is an arbitrary and unique port referenced in
        # the "REST API healtcheck monitoring endpoints map" here below
        # and in the backserver servers mapping "map"
        server 127.0.0.1:10080;
        server 127.0.0.1:10081;
}

#
# REST API healtcheck monitoring endpoints map
#
# This map must be defined as:
# key -> all ports declared in the "server_check" upstream
# value -> the REST API endpoint to be called for healthcheck evaluation (see healtcheck.js)
#
map $server_port $healthcheck_endpoint {
        10080   http://192.168.1.30:5000/stats;
        10081   http://192.168.1.31:5000/stats;
}

#
# Mapping between port number and backend server position
# in the http_balancing_upstream upstream for HTTP(S) traffic (declared in conf.d/loadbalancer.conf)
# and in the tcp_balancing_upstream for TCP/UDP traffic (declared in stream-conf.d/stream-loadbalancer.conf)
#
# This map must be defined as:
# key -> all ports declared in the "server_check" upstream
# value -> position of the upstream server used for load balancing as listed in the "http_balancing_upstream" upstream (for HTTP/S traffic) or the "tcp_balancing_upstream" (for TCP/UDP traffic)
#
# In this example 1 is 192.168.1.30:8080 and 2 is 192.168.1.31:8080 (see conf.d/loadbalancer.conf)
#
map $server_port $backend_server_entry {
        10080   1;
        10081   2;
}

#
# Internal monitoring server - checks destination servers health every 3 seconds
#
server {
        location /dummy {
                internal;

                health_check interval=3;
                proxy_pass http://server_check;
        }
}

# Healtcheck server - njs-based healthcheck evaluation and dynamic balancing_upstream configuration
# This server must listen on all ip:port defined as servers in the "server_check" upstream
server {
        listen 127.0.0.1:10080;
        listen 127.0.0.1:10081;

        access_log /var/log/nginx/healthcheck-access_log healthcheck_log;
        error_log /var/log/nginx/healthcheck-error_log notice;

        # Main location: hooks the javascript code
        location / {
                js_content healthcheck.check;
        }

        # Internal location called by the javascript code through a subrequest.
        # This location sends the actual REST API request to the monitoring endpoint
        location ~ /healthCheck/(.*) {
                internal;
                proxy_pass $1$query_string;
        }

        # Internal location to set an upstream server as "up"
        # This gets called by the javascript code through a subrequest
	location ~ /upstream/up/(.*) {
		internal;
		proxy_method PATCH;
		proxy_set_body '{"down":"false"}';

                # Use to dynamically update the HTTP (conf.d) upstream configured in conf.d/loadbalancer.conf
		proxy_pass http://127.0.0.1:8080/api/8/http/upstreams/http_balancing_upstream/servers/$1;

                # Use to dynamically update the TCP/UDP (stream-conf.d) upstream configured in stream-conf.d/stream-loadbalancer.conf
		#proxy_pass http://127.0.0.1:8080/api/8/stream/upstreams/tcp_balancing_upstream/servers/$1;
	}

        # Internal location to set an upstream server as "down"
        # This gets called by the javascript code through a subrequest
	location ~ /upstream/down/(.*) {
		internal;
		proxy_method PATCH;
		proxy_set_body '{"down":"true"}';

                # Use to dynamically update the HTTP (conf.d) upstream configured in conf.d/loadbalancer.conf
		proxy_pass http://127.0.0.1:8080/api/8/http/upstreams/http_balancing_upstream/servers/$1;

                # Use to dynamically update the TCP/UDP (stream-conf.d) upstream configured in stream-conf.d/stream-loadbalancer.conf
		#proxy_pass http://127.0.0.1:8080/api/8/stream/upstreams/tcp_balancing_upstream/servers/$1;
	}
}

# This enables NGINX Plus REST API access, needed by the javascript code
server {
        listen 0.0.0.0:8080;

        location /api {
                api write=on;
                # Allows full API access, restrict access for real-world usage
                allow all;
        }

        location / {
                root /usr/share/nginx/html;
                index dashboard.html;
                # Allows full Dashboard access, restrict access for real-world usage
                allow all;
        }
}