# HG changeset patch
# User Kim Alvefur <zash@zash.se>
# Date 1637259967 -3600
# Node ID 13e913471b7583ede47073510bf9620d4b086409
# Parent  fd90925dc2396160f4976ba5d6eac09e40e96be8
mod_http_admin_api: Ensure freshness of metrics when in manual mode

When in manual collection mode, as recommended for Prometheus,
collection needs to be triggered manually, or they would be stale,
possibly dating from the start of the server. This might vary per metric
depending on how and when the metrics are gathered.

diff -r fd90925dc239 -r 13e913471b75 mod_http_admin_api/mod_http_admin_api.lua
--- a/mod_http_admin_api/mod_http_admin_api.lua	Thu Nov 18 09:07:40 2021 +0000
+++ b/mod_http_admin_api/mod_http_admin_api.lua	Thu Nov 18 19:26:07 2021 +0100
@@ -17,6 +17,8 @@
 
 local site_name = module:get_option_string("site_name", module.host);
 
+local manual_stats_collection = module:context("*"):get_option("statistics_interval") == "manual";
+
 local json_content_type = "application/json";
 
 local www_authenticate_header = ("Bearer realm=%q"):format(module.host.."/"..module.name);
@@ -612,6 +614,9 @@
 local function get_server_metrics(event)
 	event.response.headers["Content-Type"] = json_content_type;
 	local result = {};
+	if manual_stats_collection then
+		statsmanager.collect();
+	end
 	local families = statsmanager.get_metric_registry():get_metric_families();
 	result.memory = maybe_export_plain_gauge(families.process_resident_memory_bytes);
 	result.cpu = maybe_export_plain_counter(families.process_cpu_seconds);