Provide better guidance for misconfigured Azure metrics

[tomkerkhove]

Provide better guidance for misconfigured Azure metrics, for example an unsupported dimension name.

For example:

[20:50:00 FTL] Failed to scrape resource for metric 'azure_response_status'
Microsoft.Azure.Management.Monitor.Fluent.Models.ErrorResponseException: Operation returned an invalid status code 'BadRequest'
at Microsoft.Azure.Management.Monitor.Fluent.MetricsOperations.ListWithHttpMessagesAsync(String resourceUri, ODataQuery1 odataQuery, String timespan, Nullable1 interval, String metricnames, String aggregation, Nullable1 top, String orderby, Nullable1 resultType, String metricnamespace, Dictionary2 customHeaders, CancellationToken cancellationToken) at Microsoft.Azure.Management.Monitor.Fluent.MetricsOperationsExtensions.ListAsync(IMetricsOperations operations, String resourceUri, ODataQuery1 odataQuery, String timespan, Nullable1 interval, String metricnames, String aggregation, Nullable1 top, String orderby, Nullable1 resultType, String metricnamespace, CancellationToken cancellationToken) at Microsoft.Azure.Management.Monitor.Fluent.Models.MetricDefinitionImpl.ExecuteAsync(CancellationToken cancellationToken) at Microsoft.Azure.Management.Monitor.Fluent.Models.MetricDefinitionImpl.Microsoft.Azure.Management.Monitor.Fluent.IWithMetricsQueryExecute.ExecuteAsync(CancellationToken cancellationToken) at Promitor.Integrations.AzureMonitor.AzureMonitorClient.GetRelevantMetric(String metricName, AggregationType metricAggregation, TimeSpan metricInterval, String metricFilter, String metricDimension, IMetricDefinition metricDefinition, DateTime recordDateTime) in /src/Promitor.Integrations.AzureMonitor/AzureMonitorClient.cs:line 150 at Promitor.Integrations.AzureMonitor.AzureMonitorClient.QueryMetricAsync(String metricName, String metricDimension, AggregationType aggregationType, TimeSpan aggregationInterval, String resourceId, String metricFilter) in /src/Promitor.Integrations.AzureMonitor/AzureMonitorClient.cs:line 82 at Promitor.Core.Scraping.AzureMonitorScraper1.ScrapeResourceAsync(String subscriptionId, ScrapeDefinition1 scrapeDefinition, TResourceDefinition resourceDefinition, AggregationType aggregationType, TimeSpan aggregationInterval) in /src/Promitor.Core.Scraping/AzureMonitorScraper.cs:line 51 at Promitor.Core.Scraping.Scraper1.ScrapeAsync(ScrapeDefinition`1 scrapeDefinition) in /src/Promitor.Core.Scraping/Scraper.cs:line 69
[20:50:00 FTL] Operation returned an invalid status code 'BadRequest'

Should be enhanced so that it contains a link to https://docs.microsoft.com/en-us/azure/azure-monitor/platform/metrics-supported#microsoftnetworkapplicationgateways to find the correct dimension and, optionally, corresponding Promitor docs. This should be retrieved through every scraper that provides the link as a property.