From a721d79b9889ec08f51cbad8497ea2ba8ce0f1d5 Mon Sep 17 00:00:00 2001
From: Alejandro Revilla <apr@jpos.org>
Date: Sun, 12 Jan 2025 18:28:34 -0300
Subject: [PATCH] add /jpos/q2/status endpoint when metrics are enabled

A call to /jpos/q2/status will return either 'running' or 'stopping'.
---
 .../org/jpos/metrics/PrometheusService.java    | 18 ++++++++++++++++--
 jpos/src/main/java/org/jpos/q2/Q2.java         |  3 ++-
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/jpos/src/main/java/org/jpos/metrics/PrometheusService.java b/jpos/src/main/java/org/jpos/metrics/PrometheusService.java
index 9770fead2a..c88259f923 100644
--- a/jpos/src/main/java/org/jpos/metrics/PrometheusService.java
+++ b/jpos/src/main/java/org/jpos/metrics/PrometheusService.java
@@ -33,6 +33,8 @@ public class PrometheusService extends QBeanSupport {
     private int port;
     @Config("path")
     private String path;
+    @Config("status-path")
+    private String statusPath;
     private HttpServer server;
 
     @Override
@@ -48,6 +50,16 @@ protected void startService() throws ConfigurationException {
                     os.write(response.getBytes());
                 }
             });
+            if (statusPath != null) {
+                server.createContext(statusPath, httpExchange -> {
+                    String response = getServer().running() ? "running\n" : "stopping\n";
+                    httpExchange.getResponseHeaders().add("Content-Type", "text/plain");
+                    httpExchange.sendResponseHeaders(200, response.getBytes().length);
+                    try (OutputStream os = httpExchange.getResponseBody()) {
+                        os.write(response.getBytes());
+                    }
+                });
+            }
             Thread.ofVirtual().start(server::start);
         } catch (IOException e) {
             getLog().warn(e);
@@ -60,10 +72,12 @@ protected void stopService() {
         server.stop(2);
     }
 
-    public static Element createDescriptor (int port, String path) {
+    public static Element createDescriptor (int port, String path, String statusPath) {
         return new Element("prometheus")
           .addContent(createProperty ("port", Integer.toString(port)))
-          .addContent (createProperty ("path", path));
+          .addContent (createProperty ("path", path))
+          .addContent (createProperty ("status-path", statusPath));
+
     }
     private static Element createProperty (String name, String value) {
         return new Element ("property")
diff --git a/jpos/src/main/java/org/jpos/q2/Q2.java b/jpos/src/main/java/org/jpos/q2/Q2.java
index 30d7896287..6318160ab9 100644
--- a/jpos/src/main/java/org/jpos/q2/Q2.java
+++ b/jpos/src/main/java/org/jpos/q2/Q2.java
@@ -158,6 +158,7 @@ public class Q2 implements FileFilter, Runnable {
     private PrometheusMeterRegistry prometheusRegistry = new PrometheusMeterRegistry(PrometheusConfig.DEFAULT);
     private int metricsPort;
     private String metricsPath;
+    private final String statusPath = "/jpos/q2/status";
 
     private Counter instancesCounter = Metrics.counter("jpos.q2.instances");
     private boolean noShutdownHook;
@@ -244,7 +245,7 @@ public void run () {
             }
             if (metricsPort != 0) {
                 deployElement(
-                  PrometheusService.createDescriptor(metricsPort, metricsPath),
+                  PrometheusService.createDescriptor(metricsPort, metricsPath, statusPath),
                   "00_prometheus-" + getInstanceId() + ".xml", false, true);
             }