Support Azure Sovereign Environments with endpoint_url option (influx…

…data#5453)

plugins/outputs/azure_monitor/README.md

@@ -40,6 +40,11 @@ written as a dimension on each Azure Monitor metric.
   ## The Azure Resource ID against which metric will be logged, e.g.
   ##   ex: resource_id = "/subscriptions/<subscription_id>/resourceGroups/<resource_group>/providers/Microsoft.Compute/virtualMachines/<vm_name>"
   # resource_id = ""
+
+  ## Optionally, if in Azure US Government, China, or other sovereign
+  ## cloud environment, set the appropriate REST endpoint for receiving
+  ## metrics. (Note: region may be  unused in this context)
+  # endpoint_url = "https://monitoring.core.usgovcloudapi.net"
 ```
 
 ### Setup

plugins/outputs/azure_monitor/azure_monitor.go

@@ -31,6 +31,7 @@ type AzureMonitor struct {
 	StringsAsDimensions bool   `toml:"strings_as_dimensions"`
 	Region              string
 	ResourceID          string `toml:"resource_id"`
+	EndpointUrl         string `toml:"endpoint_url"`
 
 	url    string
 	auth   autorest.Authorizer
@@ -65,6 +66,7 @@ const (
 	vmInstanceMetadataURL = "http://169.254.169.254/metadata/instance?api-version=2017-12-01"
 	resourceIDTemplate    = "/subscriptions/%s/resourceGroups/%s/providers/Microsoft.Compute/virtualMachines/%s"
 	urlTemplate           = "https://%s.monitoring.azure.com%s/metrics"
+	urlOverrideTemplate   = "%s%s/metrics"
 	maxRequestBodySize    = 4000000
 )
 
@@ -91,6 +93,11 @@ var sampleConfig = `
   ## The Azure Resource ID against which metric will be logged, e.g.
   ##   ex: resource_id = "/subscriptions/<subscription_id>/resourceGroups/<resource_group>/providers/Microsoft.Compute/virtualMachines/<vm_name>"
   # resource_id = ""
+
+  ## Optionally, if in Azure US Government, China or other sovereign
+  ## cloud environment, set appropriate REST endpoint for receiving
+  ## metrics. (Note: region may be unused in this context)
+  # endpoint_url = "https://monitoring.core.usgovcloudapi.net"
 `
 
 // Description provides a description of the plugin
@@ -125,6 +132,8 @@ func (a *AzureMonitor) Connect() error {
 	var err error
 	var region string
 	var resourceID string
+	var endpointUrl string
+
 	if a.Region == "" || a.ResourceID == "" {
 		// Pull region and resource identifier
 		region, resourceID, err = vmInstanceMetadata(a.client)
@@ -138,13 +147,21 @@ func (a *AzureMonitor) Connect() error {
 	if a.ResourceID != "" {
 		resourceID = a.ResourceID
 	}
+	if a.EndpointUrl != "" {
+		endpointUrl = a.EndpointUrl
+	}
 
 	if resourceID == "" {
 		return fmt.Errorf("no resource ID configured or available via VM instance metadata")
 	} else if region == "" {
 		return fmt.Errorf("no region configured or available via VM instance metadata")
 	}
-	a.url = fmt.Sprintf(urlTemplate, region, resourceID)
+
+	if endpointUrl == "" {
+		a.url = fmt.Sprintf(urlTemplate, region, resourceID)
+	} else {
+		a.url = fmt.Sprintf(urlOverrideTemplate, endpointUrl, resourceID)
+	}
 
 	log.Printf("D! Writing to Azure Monitor URL: %s", a.url)