Merge pull request #14978 from rgacogne/ddist19-backport-14888

dnsdist-1.9.x: Backport of 14888 - Custom metrics: better error messages, small doc improvements

pdns/dnsdistdist/dnsdist-metrics.cc

@@ -203,7 +203,7 @@ std::variant<uint64_t, Error> incrementCustomCounter(const std::string_view& nam
     metric->second.d_value += step;
     return metric->second.d_value.load();
   }
-  return std::string("Unable to increment custom metric '") + std::string(name) + "': no such metric";
+  return std::string("Unable to increment custom metric '") + std::string(name) + "': no such counter";
 }
 
 std::variant<uint64_t, Error> decrementCustomCounter(const std::string_view& name, uint64_t step)
@@ -214,7 +214,7 @@ std::variant<uint64_t, Error> decrementCustomCounter(const std::string_view& nam
     metric->second.d_value -= step;
     return metric->second.d_value.load();
   }
-  return std::string("Unable to decrement custom metric '") + std::string(name) + "': no such metric";
+  return std::string("Unable to decrement custom metric '") + std::string(name) + "': no such counter";
 }
 
 std::variant<double, Error> setCustomGauge(const std::string_view& name, const double value)
@@ -226,7 +226,7 @@ std::variant<double, Error> setCustomGauge(const std::string_view& name, const d
     return value;
   }
 
-  return std::string("Unable to set metric '") + std::string(name) + "': no such metric";
+  return std::string("Unable to set metric '") + std::string(name) + "': no such gauge";
 }
 
 std::variant<double, Error> getCustomMetric(const std::string_view& name)

pdns/dnsdistdist/docs/reference/custommetrics.rst

@@ -17,11 +17,14 @@ Then you can update those at runtime using the following functions, depending on
   .. versionchanged:: 1.8.1
     This function can now be used at runtime, instead of only at configuration time.
 
-  Return true if declaration was successful
+  Re-declaring an existing metric with the same name and type will not reset it.
+  Re-declaring with the same name but a different type will cause one of them to be masked.
+
+  Returns true if declaration was successful.
 
   :param str name: The name of the metric, lowercase alphanumerical characters and dashes (-) only
   :param str type: The desired type in ``gauge`` or ``counter``
-  :param str name: The description of the metric
+  :param str description: The description of the metric
   :param str prometheusName: The name to use in the prometheus metrics, if supplied. Otherwise the regular name will be used, prefixed with ``dnsdist_`` and ``-`` replaced by ``_``.
 
 .. function:: incMetric(name [, step]) -> int
@@ -31,8 +34,9 @@ Then you can update those at runtime using the following functions, depending on
   .. versionchanged:: 1.8.1
     Optional ``step`` parameter added.
 
-  Increment counter by one (or more, see the ``step`` parameter), will issue an error if the metric is not declared or not a ``counter``
-  Return the new value
+  Increment counter by one (or more, see the ``step`` parameter), will issue an error if the metric is not declared or not a ``counter``.
+
+  Returns the new value.
 
   :param str name: The name of the metric
   :param int step: By how much the counter should be incremented, default to 1.
@@ -44,8 +48,9 @@ Then you can update those at runtime using the following functions, depending on
   .. versionchanged:: 1.8.1
     Optional ``step`` parameter added.
 
-  Decrement counter by one (or more, see the ``step`` parameter), will issue an error if the metric is not declared or not a ``counter``
-  Return the new value
+  Decrement counter by one (or more, see the ``step`` parameter), will issue an error if the metric is not declared or not a ``counter``.
+
+  Returns the new value.
 
   :param str name: The name of the metric
   :param int step: By how much the counter should be decremented, default to 1.
@@ -54,16 +59,17 @@ Then you can update those at runtime using the following functions, depending on
 
   .. versionadded:: 1.8.0
 
-  Get metric value
+  Get metric value.
 
   :param str name: The name of the metric
 
 .. function:: setMetric(name, value) -> double
 
   .. versionadded:: 1.8.0
 
-  Set the new value, will issue an error if the metric is not declared or not a ``gauge``
-  Return the new value
+  Set the new value, will issue an error if the metric is not declared or not a ``gauge``.
+
+  Return the new value.
 
   :param str name: The name of the metric
   :param double value: The new value