ENG-27785: set Content-Type, default metrics server (port 12223) to l…

.github/workflows/release.yml

@@ -15,6 +15,8 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
       - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
       - name: Build the Docker image
         run: |
           mkdir target

.github/workflows/test.yml

@@ -15,6 +15,8 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
       - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
       - name: Run tests in docker container
         run: |
           mkdir target

src/main/java/org/voltdb/meshmonitor/cli/MeshMonitorCommand.java

@@ -83,8 +83,8 @@ public class MeshMonitorCommand implements Callable<Integer> {
 
     @CommandLine.Option(
             names = {"-m", "--metrics-bind"},
-            description = "Bind address of a metrics server port in format ipv4[:port]",
-            defaultValue = "127.0.0.1:12223",
+            description = "Bind address for metrics server in format [host][:port]. Default is 12223 for all interfaces",
+            defaultValue = "12223",
             converter = InetSocketAddressConverter.class)
     private InetSocketAddress metricsBindAddress;
 

src/main/java/org/voltdb/meshmonitor/metrics/MetricsHttpHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2024 Volt Active Data Inc.
+ * Copyright (C) 2024-2025 Volt Active Data Inc.
  *
  * Use of this source code is governed by an MIT
  * license that can be found in the LICENSE file or at
@@ -53,8 +53,12 @@ private void handleGetRequest(HttpExchange httpExchange) throws IOException {
         try (OutputStream outputStream = httpExchange.getResponseBody()) {
             StringBuilder output = new StringBuilder();
             serverManager.getMonitors().forEach(monitor -> monitorStatsPrinter.print(output, monitor));
-
             String prometheusResponse = output.toString();
+
+            // Set Content-Type header (required by Prometheus)
+            // see: https://prometheus.io/docs/instrumenting/exposition_formats/#text-format-details
+            httpExchange.getResponseHeaders().set("Content-Type", "text/plain; version=0.0.4; charset=utf-8");
+
             httpExchange.sendResponseHeaders(200, prometheusResponse.length());
 
             outputStream.write(prometheusResponse.getBytes());