Convert top level deserializers

docs/configuration/v1.x/metrics/index.md

@@ -38,7 +38,6 @@ Every metric that is being declared needs to define the following fields:
 - `description` - Description for the metric that will be exposed in the scrape
   endpoint for Prometheus.
 - `resourceType` - Defines what type of resource needs to be queried.
-- `labels` - Defines a set of custom labels to include for a given metric.
 - `azureMetricConfiguration.metricName` - The name of the metric in Azure Monitor
   to query
 - `azureMetricConfiguration.aggregation.type` - The aggregation that needs to be
@@ -57,6 +56,7 @@ Additionally, the following fields are optional:
   - ☝ *Promitor simply acts as a proxy and will not validate if it's supported or
      not, we recommend verifying that the dimension is supported in the
      [official documentation](https://docs.microsoft.com/en-us/azure/azure-monitor/platform/metrics-supported)*
+- `labels` - Defines a set of custom labels to include for a given metric.
 - `scraping.schedule` - A scraping schedule for the individual metric; overrides
   the the one specified in `metricDefaults`
 

src/Promitor.Core.Scraping/Configuration/Serialization/Deserializer.cs

@@ -77,18 +77,42 @@ public List<TObject> Deserialize(YamlSequenceNode nodes, IErrorReporter errorRep
             return deserializedObjects;
         }
 
+        public object DeserializeObject(YamlMappingNode node, IErrorReporter errorReporter)
+        {
+            return Deserialize(node, errorReporter);
+        }
+
         protected void MapRequired<TReturn>(Expression<Func<TObject, TReturn>> accessorExpression, Func<string, KeyValuePair<YamlNode, YamlNode>, IErrorReporter, object> customMapperFunc = null)
         {
             var memberExpression = (MemberExpression)accessorExpression.Body;
             _fields[GetName(memberExpression)] = new FieldContext(memberExpression.Member as PropertyInfo, true, default(TReturn), customMapperFunc);
         }
+
+        protected void MapRequired<TReturn>(
+            Expression<Func<TObject, TReturn>> accessorExpression, IDeserializer deserializer)
+            where TReturn: new()
+        {
+            var memberExpression = (MemberExpression)accessorExpression.Body;
+            _fields[GetName(memberExpression)] = new FieldContext(
+                memberExpression.Member as PropertyInfo, true, default(TReturn), null, deserializer);
+        }
 
-        protected void MapOptional<TReturn>(Expression<Func<TObject, TReturn>> accessorExpression, TReturn defaultValue = default, Func<string, KeyValuePair<YamlNode, YamlNode>, IErrorReporter, object> customMapperFunc = null)
+        protected void MapOptional<TReturn>(
+            Expression<Func<TObject, TReturn>> accessorExpression, TReturn defaultValue = default, Func<string, KeyValuePair<YamlNode, YamlNode>, IErrorReporter, object> customMapperFunc = null)
         {
             var memberExpression = (MemberExpression)accessorExpression.Body;
             _fields[GetName(memberExpression)] = new FieldContext(memberExpression.Member as PropertyInfo, false, defaultValue, customMapperFunc);
         }
 
+        protected void MapOptional<TReturn>(
+            Expression<Func<TObject, TReturn>> accessorExpression, IDeserializer deserializer)
+            where TReturn: new()
+        {
+            var memberExpression = (MemberExpression)accessorExpression.Body;
+            _fields[GetName(memberExpression)] = new FieldContext(
+                memberExpression.Member as PropertyInfo, false, default(TReturn), null, deserializer);
+        }
+
         private static string GetName(MemberExpression memberExpression)
         {
             return Char.ToLowerInvariant(memberExpression.Member.Name[0]) + memberExpression.Member.Name.Substring(1);
@@ -102,6 +126,12 @@ private static object GetFieldValue(
                 return fieldContext.CustomMapperFunc(fieldNodePair.Value.ToString(), fieldNodePair, errorReporter);
             }
 
+
+            if (fieldContext.Deserializer != null)
+            {
+                return fieldContext.Deserializer.DeserializeObject((YamlMappingNode)fieldNodePair.Value, errorReporter);
+            }
+
             var propertyType = Nullable.GetUnderlyingType(fieldContext.PropertyInfo.PropertyType) ?? fieldContext.PropertyInfo.PropertyType;
             if (propertyType.IsEnum)
             {
@@ -146,19 +176,21 @@ private static object GetFieldValue(
 
         private class FieldContext
         {
-            public FieldContext(PropertyInfo propertyInfo, bool isRequired, object defaultValue, Func<string, KeyValuePair<YamlNode, YamlNode>, IErrorReporter, object> customMapperFunc)
+            public FieldContext(PropertyInfo propertyInfo, bool isRequired, object defaultValue, Func<string, KeyValuePair<YamlNode, YamlNode>, IErrorReporter, object> customMapperFunc, IDeserializer deserializer = null)
             {
                 CustomMapperFunc = customMapperFunc;
                 PropertyInfo = propertyInfo;
                 IsRequired = isRequired;
                 DefaultValue = defaultValue;
+                Deserializer = deserializer;
             }
 
             public bool HasBeenSet { get; private set; }
             public PropertyInfo PropertyInfo { get; }
             public bool IsRequired { get; }
             public object DefaultValue { get; }
             public Func<string, KeyValuePair<YamlNode, YamlNode>, IErrorReporter, object> CustomMapperFunc { get; }
+            public IDeserializer Deserializer { get; }
 
             public void SetValue(TObject target, object value)
             {

src/Promitor.Core.Scraping/Configuration/Serialization/IDeserializer.cs

@@ -3,11 +3,25 @@
 
 namespace Promitor.Core.Scraping.Configuration.Serialization
 {
+    /// <summary>
+    /// An object that can deserialize a yaml node into an object.
+    /// </summary>
+    public interface IDeserializer
+    {
+        /// <summary>
+        /// Deserializes the specified node.
+        /// </summary>
+        /// <param name="node">The node to deserialize.</param>
+        /// <param name="errorReporter">Used to report deserialization errors.</param>
+        /// <returns>The deserialized object.</returns>
+        object DeserializeObject(YamlMappingNode node, IErrorReporter errorReporter);
+    }
+
     /// <summary>
     /// An object that can deserialize a yaml node into an object.
     /// </summary>
     /// <typeparam name="TObject">The type of object that can be deserialized.</typeparam>
-    public interface IDeserializer<TObject> where TObject: new()
+    public interface IDeserializer<TObject> : IDeserializer where TObject: new()
     {
         /// <summary>
         /// Deserializes the specified node.

src/Promitor.Core.Scraping/Configuration/Serialization/v1/Core/AzureMetricConfigurationDeserializer.cs

@@ -1,52 +1,16 @@
 using Microsoft.Extensions.Logging;
 using Promitor.Core.Scraping.Configuration.Serialization.v1.Model;
-using YamlDotNet.RepresentationModel;
 
 namespace Promitor.Core.Scraping.Configuration.Serialization.v1.Core
 {
     public class AzureMetricConfigurationDeserializer : Deserializer<AzureMetricConfigurationV1>
     {
-        private const string MetricNameTag = "metricName";
-        private const string DimensionTag = "dimension";
-        private const string AggregationTag = "aggregation";
-        private readonly IDeserializer<MetricDimensionV1> _dimensionDeserializer;
-        private readonly IDeserializer<MetricAggregationV1> _aggregationDeserializer;
-
         public AzureMetricConfigurationDeserializer(IDeserializer<MetricDimensionV1> dimensionDeserializer, IDeserializer<MetricAggregationV1> aggregationDeserializer, ILogger<AzureMetricConfigurationDeserializer> logger)
             : base(logger)
         {
-            _dimensionDeserializer = dimensionDeserializer;
-            _aggregationDeserializer = aggregationDeserializer;
-        }
-
-        public override AzureMetricConfigurationV1 Deserialize(YamlMappingNode node, IErrorReporter errorReporter)
-        {
-            return new AzureMetricConfigurationV1
-            {
-                MetricName = node.GetString(MetricNameTag),
-                Dimension = DeserializeDimension(node, errorReporter),
-                Aggregation = DeserializeAggregation(node, errorReporter)
-            };
-        }
-
-        private MetricAggregationV1 DeserializeAggregation(YamlMappingNode node, IErrorReporter errorReporter)
-        {
-            if (node.Children.TryGetValue(AggregationTag, out var aggregationNode))
-            {
-                return _aggregationDeserializer.Deserialize((YamlMappingNode) aggregationNode, errorReporter);
-            }
-
-            return null;
-        }
-
-        private MetricDimensionV1 DeserializeDimension(YamlMappingNode node, IErrorReporter errorReporter)
-        {
-            if (node.Children.TryGetValue(DimensionTag, out var aggregationNode))
-            {
-                return _dimensionDeserializer.Deserialize((YamlMappingNode)aggregationNode, errorReporter);
-            }
-
-            return null;
+            MapRequired(config => config.MetricName);
+            MapRequired(config => config.Dimension, dimensionDeserializer);
+            MapRequired(config => config.Aggregation, aggregationDeserializer);
         }
     }
 }

src/Promitor.Core.Scraping/Configuration/Serialization/v1/Core/MetricAggregationDeserializer.cs

@@ -1,30 +1,14 @@
-using Microsoft.Azure.Management.Monitor.Fluent.Models;
-using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging;
 using Promitor.Core.Scraping.Configuration.Serialization.v1.Model;
-using YamlDotNet.RepresentationModel;
 
 namespace Promitor.Core.Scraping.Configuration.Serialization.v1.Core
 {
     public class MetricAggregationDeserializer : Deserializer<MetricAggregationV1>
     {
-        private const string TypeTag = "type";
-        private const string IntervalTag = "interval";
-
         public MetricAggregationDeserializer(ILogger<MetricAggregationDeserializer> logger) : base(logger)
         {
-        }
-
-        public override MetricAggregationV1 Deserialize(YamlMappingNode node, IErrorReporter errorReporter)
-        {
-            var aggregationType = node.GetEnum<AggregationType>(TypeTag);
-
-            var interval = node.GetTimeSpan(IntervalTag);
-
-            return new MetricAggregationV1
-            {
-                Type = aggregationType,
-                Interval = interval
-            };
+            MapRequired(aggregation => aggregation.Type);
+            MapOptional(aggregation => aggregation.Interval);
         }
     }
 }

src/Promitor.Core.Scraping/Configuration/Serialization/v1/Core/MetricDefaultsDeserializer.cs

@@ -1,34 +1,17 @@
 using Microsoft.Extensions.Logging;
 using Promitor.Core.Scraping.Configuration.Serialization.v1.Model;
-using YamlDotNet.RepresentationModel;
 
 namespace Promitor.Core.Scraping.Configuration.Serialization.v1.Core
 {
     public class MetricDefaultsDeserializer : Deserializer<MetricDefaultsV1>
     {
-        private const string AggregationTag = "aggregation";
-        private const string ScrapingTag = "scraping";
-
-        private readonly IDeserializer<AggregationV1> _aggregationDeserializer;
-        private readonly IDeserializer<ScrapingV1> _scrapingDeserializer;
-
         public MetricDefaultsDeserializer(
             IDeserializer<AggregationV1> aggregationDeserializer,
             IDeserializer<ScrapingV1> scrapingDeserializer,
             ILogger<MetricDefaultsDeserializer> logger) : base(logger)
         {
-            _aggregationDeserializer = aggregationDeserializer;
-            _scrapingDeserializer = scrapingDeserializer;
-        }
-
-        public override MetricDefaultsV1 Deserialize(YamlMappingNode node, IErrorReporter errorReporter)
-        {
-            var defaults = new MetricDefaultsV1();
-
-            defaults.Aggregation = node.DeserializeChild(AggregationTag, _aggregationDeserializer, errorReporter);
-            defaults.Scraping = node.DeserializeChild(ScrapingTag, _scrapingDeserializer, errorReporter);
-
-            return defaults;
+            MapOptional(defaults => defaults.Aggregation, aggregationDeserializer);
+            MapRequired(defaults => defaults.Scraping, scrapingDeserializer);
         }
     }
 }

src/Promitor.Core.Scraping/Configuration/Serialization/v1/Core/MetricDefinitionDeserializer.cs

@@ -7,76 +7,55 @@ namespace Promitor.Core.Scraping.Configuration.Serialization.v1.Core
 {
     public class MetricDefinitionDeserializer : Deserializer<MetricDefinitionV1>
     {
-        private const string NameTag = "name";
-        private const string DescriptionTag = "description";
-        private const string ResourceTypeTag = "resourceType";
-        private const string LabelsTag = "labels";
-        private const string AzureMetricConfigurationTag = "azureMetricConfiguration";
-        private const string ScrapingTag = "scraping";
         private const string ResourcesTag = "resources";
-
-        private readonly IDeserializer<AzureMetricConfigurationV1> _azureMetricConfigurationDeserializer;
-        private readonly IDeserializer<ScrapingV1> _scrapingDeserializer;
         private readonly IAzureResourceDeserializerFactory _azureResourceDeserializerFactory;
 
         public MetricDefinitionDeserializer(IDeserializer<AzureMetricConfigurationV1> azureMetricConfigurationDeserializer,
             IDeserializer<ScrapingV1> scrapingDeserializer,
             IAzureResourceDeserializerFactory azureResourceDeserializerFactory,
             ILogger<MetricDefinitionDeserializer> logger) : base(logger)
         {
-            _azureMetricConfigurationDeserializer = azureMetricConfigurationDeserializer;
-            _scrapingDeserializer = scrapingDeserializer;
             _azureResourceDeserializerFactory = azureResourceDeserializerFactory;
+
+            MapRequired(definition => definition.Name);
+            MapRequired(definition => definition.Description);
+            MapRequired(definition => definition.ResourceType);
+            MapOptional(definition => definition.Labels);
+            MapRequired(definition => definition.AzureMetricConfiguration, azureMetricConfigurationDeserializer);
+            MapOptional(definition => definition.Scraping, scrapingDeserializer);
         }
 
         public override MetricDefinitionV1 Deserialize(YamlMappingNode node, IErrorReporter errorReporter)
         {
-            var name = node.GetString(NameTag);
-            var description = node.GetString(DescriptionTag);
-            var resourceType = node.GetEnum<ResourceType>(ResourceTypeTag);
-            var labels = node.GetDictionary(LabelsTag);
-
-            var metricDefinition = new MetricDefinitionV1
-            {
-                Name = name,
-                Description = description,
-                ResourceType = resourceType,
-                Labels = labels
-            };
+            var metricDefinition = base.Deserialize(node, errorReporter);
 
-            DeserializeAzureMetricConfiguration(node, metricDefinition, errorReporter);
-            DeserializeScraping(node, metricDefinition, errorReporter);
             DeserializeMetrics(node, metricDefinition, errorReporter);
 
             return metricDefinition;
         }
 
-        private void DeserializeAzureMetricConfiguration(YamlMappingNode node, MetricDefinitionV1 metricDefinition, IErrorReporter errorReporter)
+        private void DeserializeMetrics(YamlMappingNode node, MetricDefinitionV1 metricDefinition, IErrorReporter errorReporter)
         {
-            if (node.Children.TryGetValue(AzureMetricConfigurationTag, out var configurationNode))
+            if (metricDefinition.ResourceType == null)
             {
-                metricDefinition.AzureMetricConfiguration =
-                    _azureMetricConfigurationDeserializer.Deserialize((YamlMappingNode) configurationNode, errorReporter);
+                return;
             }
-        }
 
-        private void DeserializeScraping(YamlMappingNode node, MetricDefinitionV1 metricDefinition, IErrorReporter errorReporter)
-        {
-            if (node.Children.TryGetValue(ScrapingTag, out var scrapingNode))
+            if (metricDefinition.ResourceType == ResourceType.NotSpecified)
             {
-                metricDefinition.Scraping = _scrapingDeserializer.Deserialize((YamlMappingNode)scrapingNode, errorReporter);
+                errorReporter.ReportError(node.Children["resourceType"], "'resourceType' must not be set to 'NotSpecified'.");
+                return;
             }
-        }
 
-        private void DeserializeMetrics(YamlMappingNode node, MetricDefinitionV1 metricDefinition, IErrorReporter errorReporter)
-        {
-            if (metricDefinition.ResourceType != null &&
-                metricDefinition.ResourceType != ResourceType.NotSpecified &&
-                node.Children.TryGetValue(ResourcesTag, out var metricsNode))
+            if (node.Children.TryGetValue(ResourcesTag, out var metricsNode))
             {
                 var resourceDeserializer = _azureResourceDeserializerFactory.GetDeserializerFor(metricDefinition.ResourceType.Value);
                 metricDefinition.Resources = resourceDeserializer.Deserialize((YamlSequenceNode)metricsNode, errorReporter);
             }
+            else
+            {
+                errorReporter.ReportError(node, "'resources' is a required field but was not found.");
+            }
         }
     }
 }

src/Promitor.Core.Scraping/Configuration/Serialization/v1/Core/ScrapingDeserializer.cs

@@ -6,24 +6,9 @@ namespace Promitor.Core.Scraping.Configuration.Serialization.v1.Core
 {
     public class ScrapingDeserializer : Deserializer<ScrapingV1>
     {
-        private const string ScheduleTag = "schedule";
-
         public ScrapingDeserializer(ILogger<ScrapingDeserializer> logger) : base(logger)
         {
-        }
-
-        public override ScrapingV1 Deserialize(YamlMappingNode node, IErrorReporter errorReporter)
-        {
-            var scraping = new ScrapingV1();
-
-            scraping.Schedule = node.GetString(ScheduleTag);
-
-            if (scraping.Schedule == null)
-            {
-                Logger.LogError("No default metric scraping schedule was configured!");
-            }
-
-            return scraping;
+            MapRequired(scraping => scraping.Schedule);
         }
     }
 }