Simple script to export metrics to Prometheus

lrpm-prometheus-metrics.php

@@ -0,0 +1,102 @@
+<?php
+# php -S 127.0.0.1:8080 lrpm-prometheus-metrics.php
+
+class PrometheusMetric
+{
+    private $name;
+    private $value;
+    private $labels;
+    private $timestamp;
+
+    public function __construct(string $name, $value, array $labels = [], $timestamp = null)
+    {
+        $this->name = $name;
+        $this->value = $value;
+        $this->labels = $labels;
+        $this->timestamp = $timestamp;
+    }
+
+    public function __toString(): string
+    {
+        $output = $this->name;
+        if (!empty($this->labels)) {
+            $output .= '{';
+            $sep = '';
+            foreach ($this->labels as $labelName => $labelValue) {
+                $output .= $sep . $labelName . '=' . $labelValue;
+                $sep = ',';
+            }
+            $output .= '}';
+        }
+        $output .= ' ' . $this->value;
+        if (isset($this->timestamp)) $output .= ' ' . $this->timestamp;
+        return $output;
+    }
+}
+
+class PrometheusMetricsBuilder
+{
+    private $metrics = [];
+    private $text = '';
+
+    public function add(PrometheusMetric $metric): void
+    {
+        $this->metrics[] = $metric;
+    }
+
+    public function __toString(): string
+    {
+        foreach ($this->metrics as $metric) {
+            $this->text .= $metric->__toString() . PHP_EOL;
+        }
+        return $this->text;
+    }
+}
+
+function get_number_of_active_tasks(array $status): int
+{
+    $active_tasks = array_filter($status, function ($task) {
+        return isset($task['state']['pid']) && is_int($task['state']['pid']);
+    });
+    return count($active_tasks);
+}
+
+function lrpm_status_to_prometheus_metrics(array $status): string
+{
+    $metricsBuilder = new PrometheusMetricsBuilder();
+
+    $taskCount = count($status);
+    $metricsBuilder->add(new PrometheusMetric('lrpm_task_count', $taskCount));
+
+    $activeTaskCount = get_number_of_active_tasks($status);
+    $inactiveTaskCount = $taskCount - $activeTaskCount;
+    $metricsBuilder->add(new PrometheusMetric('lrpm_inactive_task_count', $inactiveTaskCount));
+
+    foreach ($status as $jobId => $jobStatus) {
+        $config = $jobStatus['config'];
+        $state = $jobStatus['state'];
+        $name = $config['name'];
+        $workerClass = $config['workerClass'];
+        $mtime = $config['mtime'];
+        if (isset($state['restartAt']) && $state['restartAt'] > $state['startedAt']) {
+            $backoffDuration = $state['restartAt'] - $state['startedAt'];
+            $labels = [
+                'id' => $jobId,
+                'name' => $name
+            ];
+            if (isset($state['lastExitCode'])) $labels['last_exit_code'] = $state['lastExitCode'];
+            $metricsBuilder->add(new PrometheusMetric('lrpm_task_backoff', $backoffDuration, $labels));
+        }
+    }
+
+    return $metricsBuilder->__toString();
+}
+
+// main entry point
+
+$program = __DIR__ . '/bin/lrpmctl';
+$request = 'jsonstatus';
+$json = shell_exec("$program $request");
+$status = json_decode($json, true);
+$output = lrpm_status_to_prometheus_metrics($status);
+echo($output);