feat: make metrics retention configurable

README.md

@@ -70,6 +70,7 @@ By default the exporter will start with sensible default values. Configuration c
 
 -  --listen.host: `default=127.0.0.1` 
 -  --listen.port `default=127.0.0.1`
+-  --metrics.retention `default=30000`
 -  --metrics.endpoint `default=/metrics` 
 -  --metrics.prefix `default=what`
 -  --metrics.with-timestamp `default=false`

lib/flags.js

@@ -20,6 +20,11 @@ const knownFlags = {
         default: '9839',
         description: 'the port the exporter user to listen for incoming connections'
     },
+    '--metrics.retention': {
+        internalName: 'retention',
+        default: '30000',
+        description: 'how long to store user sessions before resetting metric value. Should be larger than scrape interval of your Prometheus job.'
+    },
     '--metrics.endpoint': {
         internalName: 'endpoint',
         default: '/metrics',

test/spec/flags.spec.js

@@ -8,6 +8,7 @@ describe('Flags', () => {
     const knownFlags = {
         '--listen.host': '123.0.0.1',
         '--listen.port': '48123',
+        '--metrics.retention': '2',
         '--metrics.endpoint': '/prometheus',
         '--metrics.prefix': 'where',
         '--metrics.with-timestamp': 'true',
@@ -17,6 +18,7 @@ describe('Flags', () => {
     const map = {
         '--listen.host': 'host',
         '--listen.port': 'port',
+        '--metrics.retention': 'retention',
         '--metrics.endpoint': 'endpoint',
         '--metrics.prefix': 'prefix',
         '--metrics.with-timestamp': 'timestamp',
@@ -45,7 +47,7 @@ describe('Flags', () => {
             return context
         }, [])
         const result = flags(allFlags)
-        expect(Object.keys(result)).to.have.length(6)
+        expect(Object.keys(result)).to.have.length(Object.keys(knownFlags).length)
         Object.keys(map).forEach(key => {
             expect(result[map[key]]).to.equal(knownFlags[key])
         })