Caddyfile

# global options
{
	admin off # theres no need for the admin api in railway's environment
	persist_config off # storage isn't persistent anyway
	auto_https off # railway handles https for us, this could in some cases cause issues if left enabled
	# runtime logs
	log {
		format json # set runtime log format to json mode 
	}
	# server options
	servers {
		trusted_proxies static private_ranges # trust railway's proxy
	}
}

(lb_settings) {
	lb_policy round_robin
	lb_retries 100
	lb_try_duration 10s
	lb_try_interval 250ms
}

(passive_health_checks) {
	fail_duration 60s
	max_fails 300
	unhealthy_latency 5s
	unhealthy_request_count 200
}

# site block, listens on the $PORT environment variable, automatically assigned by railway
:{$PORT} {
	# access logs
	log {
		format json # set access log format to json mode
	}

	# proxy all requests for /* to the frontend, configure these variables in the service settings
	reverse_proxy {
		# for private networking replicas are exposed as multiple dns results, use those dns results as the upstreams
		dynamic a {
			name {$FRONTEND_DOMAIN}
			port {$FRONTEND_PORT}
			refresh 1s
			dial_timeout 30s
			versions ipv4 ipv6
		}

		# configure load balancing settings
		import lb_settings

		# configure passive health checks
		import passive_health_checks

		# sets the Host header to the header to the dynamic name and port options
		header_up Host {upstream_hostport}
	}

	# the handle_path directive WILL strip /api/ from the path before proxying
	# use `handle` instead of `handle_path` if you dont want to strip the /api/ path
	# this is needed if your backend's api routes don't start with /api/
	# change paths as needed
	handle_path {$BACKEND_PATH:/api}/* {
		# the /api/ prefix WILL be stripped from the uri sent to the proxy host
		#
		# proxy all requests for /api/* to the backend, configure this variable in the service settings
		reverse_proxy {
			# for private networking replicas are exposed as multiple dns results, use those dns results as the upstreams
			dynamic a {
				name {$BACKEND_DOMAIN}
				port {$BACKEND_PORT}
				refresh 1s
				dial_timeout 30s
				versions ipv4 ipv6
			}

			# configure load balancing settings
			import lb_settings

			# configure passive health checks
			import passive_health_checks

			# sets the Host header to the header to the dynamic name and port options
			header_up Host {upstream_hostport}
		}
	}
}