From: Marek Vavruša <mvavrusa@cloudflare.com>
Date: Fri, 23 Mar 2018 18:20:36 +0000 (-0700)
Subject: http/prometheus: allow custom namespaces
X-Git-Tag: v2.4.0~30^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9107aa1d6b550b8051b1ecc76f2473cbe86ceb80;p=thirdparty%2Fknot-resolver.git

http/prometheus: allow custom namespaces
---

diff --git a/modules/http/README.rst b/modules/http/README.rst
index df21f5c4e..4798010a1 100644
--- a/modules/http/README.rst
+++ b/modules/http/README.rst
@@ -109,6 +109,17 @@ You can use it out of the box:
 	latency_count 2.000000
 	latency_sum 11.000000
 
+You can namespace the metrics in configuration, using `http.prometheus.namespace` attribute:
+
+.. code-block:: lua
+
+	http = {
+		host = 'localhost',
+	}
+
+	-- Set Prometheus namespace
+	http.prometheus.namespace = 'resolver_'
+
 Tracing requests
 ^^^^^^^^^^^^^^^^
 
diff --git a/modules/http/prometheus.lua b/modules/http/prometheus.lua
index a6d0cd044..898590efb 100644
--- a/modules/http/prometheus.lua
+++ b/modules/http/prometheus.lua
@@ -1,3 +1,8 @@
+-- Module implementation
+local M = {
+	namespace = '',
+}
+
 local snapshots, snapshots_count = {}, 120
 
 -- Gauge metrics
@@ -126,33 +131,35 @@ local function serve_prometheus()
 		elseif k == 'answer_slow' then
 			table.insert(latency, {'+Inf', v})
 		-- Counter as a fallback
-		else table.insert(render, string.format(counter, k, k, v)) end
+		else
+			local key = M.namespace .. k
+			table.insert(render, string.format(counter, key, key, v))
+		end
 	end
 	-- Fill in latency histogram
 	local function kweight(x) return tonumber(x) or math.huge end
 	table.sort(latency, function (a,b) return kweight(a[1]) < kweight(b[1]) end)
-	table.insert(render, '# TYPE latency histogram')
+	table.insert(render, string.format('# TYPE %slatency histogram', M.namespace))
 	local count, sum = 0.0, 0.0
 	for _,e in ipairs(latency) do
 		-- The information about the %Inf bin is lost, so we treat it
 		-- as a timeout (3000ms) for metrics purposes
 		count = count + e[2]
 		sum = sum + e[2] * (math.min(tonumber(e[1]), 3000.0))
-		table.insert(render, string.format('latency_bucket{le="%s"} %f', e[1], count))
+		table.insert(render, string.format('%slatency_bucket{le="%s"} %f', M.namespace, e[1], count))
 	end
-	table.insert(render, string.format('latency_count %f', count))
-	table.insert(render, string.format('latency_sum %f', sum))
+	table.insert(render, string.format('%slatency_count %f', M.namespace, count))
+	table.insert(render, string.format('%slatency_sum %f', M.namespace, sum))
 	return table.concat(render, '\n') .. '\n'
 end
 
--- Export endpoints
-return {
-	init = snapshot_start,
-	deinit = snapshot_end,
-	gauges = gauges,
-	endpoints = {
-		['/stats']     = {'application/json', getstats, stream_stats},
-		['/frequent']  = {'application/json', function () return stats.frequent() end},
-		['/metrics']   = {'text/plain; version=0.0.4', serve_prometheus},
-	}
-}
\ No newline at end of file
+-- Export module interface
+M.init = snapshot_start
+M.deinit = snapshot_end
+M.endpoints = {
+	['/stats']     = {'application/json', getstats, stream_stats},
+	['/frequent']  = {'application/json', function () return stats.frequent() end},
+	['/metrics']   = {'text/plain; version=0.0.4', serve_prometheus},
+}
+
+return M
\ No newline at end of file