Provide Container Registry scraper (#455)

Provide Container Registry scraper

Closes #325

### Configuration
```yaml
azureMetadata:
  tenantId: c8819874-9e56-4e3f-b1a8-1c0325138f27
  subscriptionId: 0f9d7fea-99e8-4768-8672-06a28514f77e
  resourceGroupName: promitor-sources
metricDefaults:
  aggregation:
    interval: 01:00:00
metrics:
  - name: demo_generic_total_pull_count
    description: "Amount of images that were pulled from the container registry"
    resourceType: ContainerRegistry
    registryName: promitor
    azureMetricConfiguration:
      metricName: TotalPullCount
      aggregation:
        type: Average
```

### Output
```yaml
# HELP demo_generic_total_pull_count Amount of images that were pulled from the container registry
# TYPE demo_generic_total_pull_count gauge
demo_generic_total_pull_count 1 1553635305491
```
### Portal
![image](https://user-images.githubusercontent.com/4345663/55034449-b5015280-4fd2-11e9-8332-f10033d647dd.png)

docs/configuration/metrics/container-registry.md

@@ -0,0 +1,27 @@
+---
+layout: default
+title: Azure Container Registry Declaration
+---
+
+## Azure Container Registry
+You can declare to scrape an Azure Container Registry via the `ContainerRegistry` resource type.
+
+The following fields need to be provided:
+- `containerGroup` - The name of the container group
+
+All supported metrics are not documented in the official [Azure Monitor documentation](https://docs.microsoft.com/en-us/azure/azure-monitor/platform/metrics-supported) documentation yet, but it's being added via [this PR](https://github.com/MicrosoftDocs/azure-docs/pull/27991).
+
+Example:
+```yaml
+name: demo_container_registry_total_pull_count
+description: "Amount of images that were pulled from the container registry"
+resourceType: ContainerRegistry
+registryName: promitor
+azureMetricConfiguration:
+  metricName: TotalPullCount
+  aggregation:
+    type: Average
+```
+
+[&larr; back to metrics declarations](/configuration/metrics)<br />
+[&larr; back to introduction](/)

docs/configuration/metrics/index.md

@@ -71,9 +71,10 @@ Every Azure service is supported and can be scraped by using the [Generic Azure
 We also provide a simplified way to configure the following Azure resources:
 
 - [Azure Container Instances](container-instances)
+- [Azure Container Registry](container-registry)
 - [Azure Service Bus Queue](service-bus-queue)
-- [Azure Storage Queue](storage-queue)
 - [Azure Virtual Machine](virtual-machine)
+- [Azure Storage Queue](storage-queue)
 
 Want to help out? Create an issue and [contribute a new scraper](https://github.com/tomkerkhove/promitor/blob/master/adding-a-new-scraper.md).
 

src/Promitor.Core.Scraping/Configuration/Model/Metrics/ResourceTypes/ContainerRegistryMetricDefinition.cs

@@ -0,0 +1,8 @@
+namespace Promitor.Core.Scraping.Configuration.Model.Metrics.ResourceTypes
+{
+    public class ContainerRegistryMetricDefinition : MetricDefinition
+    {
+        public string RegistryName { get; set; }
+        public override ResourceType ResourceType { get; } = ResourceType.ContainerRegistry;
+    }
+}

src/Promitor.Core.Scraping/Configuration/Model/ResourceType.cs

@@ -7,6 +7,7 @@ public enum ResourceType
         Generic = 2,
         StorageQueue = 3,
         ContainerInstance = 4,
-        VirtualMachine = 5
+        VirtualMachine = 5,
+        ContainerRegistry = 6
     }
 }

src/Promitor.Core.Scraping/Configuration/Serialization/Deserializers/ContainerRegistryMetricDeserializer.cs

@@ -0,0 +1,22 @@
+using Promitor.Core.Scraping.Configuration.Model.Metrics;
+using Promitor.Core.Scraping.Configuration.Model.Metrics.ResourceTypes;
+using YamlDotNet.RepresentationModel;
+
+namespace Promitor.Core.Scraping.Configuration.Serialization.Deserializers
+{
+    internal class ContainerRegistryMetricDeserializer : GenericAzureMetricDeserializer
+    {
+        /// <summary>Deserializes the specified Container Registry metric node from the YAML configuration file.</summary>
+        /// <param name="metricNode">The metric node to deserialize to Container Registry configuration</param>
+        /// <returns>A new <see cref="MetricDefinition"/> object (strongly typed as a <see cref="ContainerRegistryMetricDefinition"/>) </returns>
+        internal override MetricDefinition Deserialize(YamlMappingNode metricNode)
+        {
+            var metricDefinition = base.DeserializeMetricDefinition<ContainerRegistryMetricDefinition>(metricNode);
+
+            var registryName = metricNode.Children[new YamlScalarNode("registryName")];
+            metricDefinition.RegistryName = registryName?.ToString();
+
+            return metricDefinition;
+        }
+    }
+}

src/Promitor.Core.Scraping/Factories/MetricDeserializerFactory.cs

@@ -19,6 +19,8 @@ internal static GenericAzureMetricDeserializer GetDeserializerFor(Configuration.
                     return new ContainerInstanceMetricDeserializer();
                 case Configuration.Model.ResourceType.VirtualMachine:
                     return new VirtualMachineMetricDeserializer();
+                case Configuration.Model.ResourceType.ContainerRegistry:
+                    return new ContainerRegistryMetricDeserializer();
             }
 
             throw new ArgumentOutOfRangeException($@"Resource Type {resource} not supported.");

src/Promitor.Core.Scraping/Factories/MetricScraperFactory.cs

@@ -37,6 +37,8 @@ public static IScraper<MetricDefinition> CreateScraper(ResourceType metricDefini
                     return new ContainerInstanceScraper(azureMetadata, metricDefaults, azureMonitorClient, logger, exceptionTracker);
                 case ResourceType.VirtualMachine:
                     return new VirtualMachineScraper(azureMetadata, metricDefaults, azureMonitorClient, logger, exceptionTracker);
+                case ResourceType.ContainerRegistry:
+                    return new ContainerRegistryScraper(azureMetadata, metricDefaults, azureMonitorClient, logger, exceptionTracker);
                 default:
                     throw new ArgumentOutOfRangeException();
             }

src/Promitor.Core.Scraping/ResourceTypes/ContainerRegistryScraper.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+using Microsoft.Azure.Management.Monitor.Fluent.Models;
+using Microsoft.Extensions.Logging;
+using Promitor.Core.Scraping.Configuration.Model;
+using Promitor.Core.Scraping.Configuration.Model.Metrics.ResourceTypes;
+using Promitor.Core.Telemetry.Interfaces;
+using Promitor.Integrations.AzureMonitor;
+
+namespace Promitor.Core.Scraping.ResourceTypes
+{
+    public class ContainerRegistryScraper : Scraper<ContainerRegistryMetricDefinition>
+    {
+        private const string ResourceUriTemplate = "subscriptions/{0}/resourceGroups/{1}/providers/Microsoft.ContainerRegistry/registries/{2}";
+
+        public ContainerRegistryScraper(AzureMetadata azureMetadata, MetricDefaults metricDefaults, AzureMonitorClient azureMonitorClient, ILogger logger, IExceptionTracker exceptionTracker)
+            : base(azureMetadata, metricDefaults, azureMonitorClient, logger, exceptionTracker)
+        {
+        }
+
+        protected override async Task<double> ScrapeResourceAsync(string subscriptionId, string resourceGroupName, ContainerRegistryMetricDefinition metricDefinition, AggregationType aggregationType, TimeSpan aggregationInterval)
+        {
+            var resourceUri = string.Format(ResourceUriTemplate, subscriptionId, resourceGroupName, metricDefinition.RegistryName);
+
+            var metricName = metricDefinition.AzureMetricConfiguration.MetricName;
+            var foundMetricValue = await AzureMonitorClient.QueryMetricAsync(metricName, aggregationType, aggregationInterval, resourceUri);
+
+            return foundMetricValue;
+        }
+    }
+}

src/Promitor.Scraper.Host/Validation/Factories/MetricValidatorFactory.cs

@@ -21,6 +21,8 @@ internal static IMetricValidator GetValidatorFor(ResourceType resourceType)
                     return new ContainerInstanceMetricValidator();
                 case ResourceType.VirtualMachine:
                     return new VirtualMachineMetricValidator();
+                case ResourceType.ContainerRegistry:
+                    return new ContainerRegistryMetricValidator();
             }
 
             throw new ArgumentOutOfRangeException(nameof(resourceType), $"No validation rules are defined for metric type '{resourceType}'");

src/Promitor.Scraper.Host/Validation/MetricDefinitions/ResourceTypes/ContainerRegistryMetricValidator.cs

@@ -0,0 +1,23 @@
+using System.Collections.Generic;
+using GuardNet;
+using Promitor.Core.Scraping.Configuration.Model.Metrics.ResourceTypes;
+
+namespace Promitor.Scraper.Host.Validation.MetricDefinitions.ResourceTypes
+{
+    internal class ContainerRegistryMetricValidator : MetricValidator<ContainerRegistryMetricDefinition>
+    {
+        protected override IEnumerable<string> Validate(ContainerRegistryMetricDefinition containerRegistryMetricDefinition)
+        {
+            Guard.NotNull(containerRegistryMetricDefinition, nameof(containerRegistryMetricDefinition));
+
+            var errorMessages = new List<string>();
+
+            if (string.IsNullOrWhiteSpace(containerRegistryMetricDefinition.RegistryName))
+            {
+                errorMessages.Add("No registry name is configured");
+            }
+
+            return errorMessages;
+        }
+    }
+}

src/Promitor.Scraper.Tests.Unit/Builders/MetricsDeclarationBuilder.cs

@@ -79,7 +79,22 @@ public string Build()
             return this;
         }
 
-        public MetricsDeclarationBuilder WithAzureStorageQueueMetric(string metricName = "promitor-storage-queue", string metricDescription = "Description for a metric", string queueName = "promitor-queue", string accountName = "promitor-account", string sasToken="?sig=promitor", string azureMetricName = AzureStorageConstants.Queues.Metrics.MessageCount)
+        public MetricsDeclarationBuilder WithContainerRegistryMetric(string metricName = "promitor-container-registry", string metricDescription = "Description for a metric", string registryName = "promitor-container-registry", string azureMetricName = "Total")
+        {
+            var azureMetricConfiguration = CreateAzureMetricConfiguration(azureMetricName);
+            var metric = new ContainerRegistryMetricDefinition
+            {
+                Name = metricName,
+                Description = metricDescription,
+                RegistryName = registryName,
+                AzureMetricConfiguration = azureMetricConfiguration
+            };
+            _metrics.Add(metric);
+
+            return this;
+        }
+
+        public MetricsDeclarationBuilder WithAzureStorageQueueMetric(string metricName = "promitor", string metricDescription = "Description for a metric", string queueName = "promitor-queue", string accountName = "promitor-account", string sasToken="?sig=promitor", string azureMetricName = AzureStorageConstants.Queues.Metrics.MessageCount)
         {
             var azureMetricConfiguration = CreateAzureMetricConfiguration(azureMetricName);
             var metric = new StorageQueueMetricDefinition