disabling prometheus for development, ability to register metric twice

Author: MadridianFox

config/prometheus.php

@@ -2,6 +2,7 @@
 
 return [
     'default_bag' => 'default',
+    'enabled' => env('PROMETHEUS_ENABLED', true),
     'bags' => [
         'default' => [
             'namespace' => env('PROMETHEUS_NAMESPACE', 'app'),

src/MetricsBag.php

@@ -62,34 +62,51 @@ public function addMiddleware(string $labelProcessorClass, array $parameters = [
 
     public function counter(string $name): Counter
     {
-        $this->metrics[$name] = new Counter($this, $name);
+        if (!isset($this->metrics[$name])) {
+            $this->metrics[$name] = new Counter($this, $name);
+        }
 
         return $this->metrics[$name];
     }
 
     public function gauge(string $name): Gauge
     {
-        $this->metrics[$name] = new Gauge($this, $name);
+        if (!isset($this->metrics[$name])) {
+            $this->metrics[$name] = new Gauge($this, $name);
+        }
 
         return $this->metrics[$name];
     }
 
     public function histogram(string $name, array $buckets): Histogram
     {
-        $this->metrics[$name] = new Histogram($this, $name, $buckets);
+        if (!isset($this->metrics[$name])) {
+            $this->metrics[$name] = new Histogram($this, $name, $buckets);
+        }
 
         return $this->metrics[$name];
     }
 
     public function summary(string $name, int $maxAgeSeconds, array $quantiles): Summary
     {
-        $this->metrics[$name] = new Summary($this, $name, $maxAgeSeconds, $quantiles);
+        if (!isset($this->metrics[$name])) {
+            $this->metrics[$name] = new Summary($this, $name, $maxAgeSeconds, $quantiles);
+        }
 
         return $this->metrics[$name];
     }
 
+    private function isPrometheusEnabled(): bool
+    {
+        return config('prometheus.enabled');
+    }
+
     public function update(string $name, $value, array $labelValues = []): void
     {
+        if (!$this->isPrometheusEnabled()) {
+            return;
+        }
+
         $metric = $this->metrics[$name] ?? null;
         $metric?->update($value, $labelValues);
     }
@@ -111,6 +128,10 @@ public function addOnDemandMetric(string $onDemandMetricClass): void
 
     public function dumpTxt(): string
     {
+        if (!$this->isPrometheusEnabled()) {
+            return '';
+        }
+
         $renderer = new RenderTextFormat();
         return $renderer->render($this->getCollectors()->getMetricFamilySamples());
     }
@@ -152,6 +173,10 @@ private function createStorageFromConnection(array $options): Adapter
 
     public function wipe(): void
     {
+        if (!$this->isPrometheusEnabled()) {
+            return;
+        }
+
         $this->getCollectors()->wipeStorage();
     }
 

tests/MetricsBagTest.php

@@ -261,6 +261,19 @@ public function testSummary()
         ]);
     }
 
+    public function testNoCreateSameMetricTwice(): void
+    {
+        $bag = new MetricsBag([
+            'namespace' => 'test',
+            'memory' => true,
+        ]);
+
+        $counter1 = $bag->counter('my_counter');
+        $counter2 = $bag->counter('my_counter');
+
+        $this->assertSame($counter1, $counter2);
+    }
+
     public function testLabelMiddleware()
     {
         config(['app.name' => 'app-name']);
@@ -327,4 +340,25 @@ public function testOnDemandMetrics()
 
         $this->assertBagContainsMetric($bag, 'test_on_demand_counter', [], 1);
     }
+
+    public function testNoUpdatesWhenPrometheusDisabled(): void
+    {
+        config([
+            'prometheus' => [
+                'enabled' => false,
+            ]
+        ]);
+
+        $bag = new MetricsBag([
+            'namespace' => 'test',
+            'memory' => true,
+        ]);
+
+        $bag->counter('my_counter')->labels(['my_label']);
+
+        $bag->update('my_counter', 1, ['my-value']);
+
+        $bagValues = $bag->dumpTxt();
+        $this->assertStringNotContainsString('test_my_counter', $bagValues);
+    }
 }