Implement built-in Prometheus exporter in monitor

mon/http_server.js

@@ -0,0 +1,46 @@
+// Copyright (c) Vitaliy Filippov, 2019+
+// License: VNPL-1.1 (see README.md for details)
+
+const fsp = require('fs').promises;
+const http = require('http');
+const https = require('https');
+
+async function create_http_server(cfg, handler)
+{
+    let server;
+    if (cfg.mon_https_cert)
+    {
+        const tls = {
+            key: await fsp.readFile(cfg.mon_https_key),
+            cert: await fsp.readFile(cfg.mon_https_cert),
+        };
+        if (cfg.mon_https_ca)
+        {
+            tls.mon_https_ca = await fsp.readFile(cfg.mon_https_ca);
+        }
+        if (cfg.mon_https_client_auth)
+        {
+            tls.requestCert = true;
+        }
+        server = https.createServer(tls, handler);
+    }
+    else
+    {
+        server = http.createServer(handler);
+    }
+    try
+    {
+        server.listen(cfg.mon_http_port || 8060, cfg.mon_http_ip || undefined);
+    }
+    catch (e)
+    {
+        console.error(
+            'HTTP server disabled because listen at address: '+
+            (cfg.mon_http_ip || '')+':'+(cfg.mon_http_port || 9090)+' failed with error: '+e
+        );
+        return null;
+    }
+    return server;
+}
+
+module.exports = { create_http_server };