1 files changed, 89 insertions, 0 deletions
diff --git a/dnsdist-prometheus.hh b/dnsdist-prometheus.hh
new file mode 100644
index 0000000..15567bf
--- /dev/null
+++ b/dnsdist-prometheus.hh
@@ -0,0 +1,89 @@
+/*
+ * This file is part of PowerDNS or dnsdist.
+ * Copyright -- PowerDNS.COM B.V. and its contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * In addition, for the avoidance of any doubt, permission is granted to
+ * link this program with OpenSSL and to (re)distribute the binaries
+ * produced as the result of such linking.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#pragma once
+
+#ifndef DISABLE_PROMETHEUS
+// Metric types for Prometheus
+enum class PrometheusMetricType: uint8_t {
+    counter = 1,
+    gauge = 2
+};
+
+// Keeps additional information about metrics
+struct MetricDefinition {
+  MetricDefinition(PrometheusMetricType _prometheusType, const std::string& _description, const std::string& customName_ = ""): description(_description), customName(customName_), prometheusType(_prometheusType) {
+  }
+
+  MetricDefinition() = default;
+
+  // Metric description
+  std::string description;
+  // Custom name, if any
+  std::string customName;
+  // Metric type for Prometheus
+  PrometheusMetricType prometheusType{PrometheusMetricType::counter};
+};
+
+struct MetricDefinitionStorage {
+  // Return metric definition by name
+  bool getMetricDetails(const std::string& metricName, MetricDefinition& metric) const {
+    const auto& metricDetailsIter = metrics.find(metricName);
+
+    if (metricDetailsIter == metrics.end()) {
+      return false;
+    }
+
+    metric = metricDetailsIter->second;
+    return true;
+  };
+
+  static bool addMetricDefinition(const std::string& name, const std::string& type, const std::string& description, const std::string& customName) {
+    static const std::map<std::string, PrometheusMetricType> namesToTypes = {
+      {"counter", PrometheusMetricType::counter},
+      {"gauge",   PrometheusMetricType::gauge},
+    };
+    auto realtype = namesToTypes.find(type);
+    if (realtype == namesToTypes.end()) {
+      return false;
+    }
+    metrics.emplace(name, MetricDefinition{realtype->second, description, customName});
+    return true;
+  }
+
+  // Return string representation of Prometheus metric type
+  std::string getPrometheusStringMetricType(PrometheusMetricType metricType) const {
+    switch (metricType) {
+      case PrometheusMetricType::counter:
+        return "counter";
+        break;
+      case PrometheusMetricType::gauge:
+        return "gauge";
+        break;
+      default:
+        return "";
+        break;
+    }
+  };
+
+  static std::map<std::string, MetricDefinition> metrics;
+};
+#endif /* DISABLE_PROMETHEUS */