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RoleEnvironment Class

Updated: December 6, 2013

Provides information about the configuration, endpoints, and status of running role instances.

Namespace: Microsoft.WindowsAzure.ServiceRuntime
Assembly: Microsoft.WindowsAzure.ServiceRuntime (in Microsoft.WindowsAzure.ServiceRuntime.dll)

[WindowsAzureHostingPermissionAttribute(SecurityAction::LinkDemand, Unrestricted=true)] 
public ref class RoleEnvironment sealed

You use the RoleEnvironment class to obtain configuration settings, local storage resources, and endpoint information for a specified role instance. The class also provides events that allow the role instance to react to configuration changes and receive notification when the role instance is about to be stopped.

noteNote
Windows Azure 1.3 and later reserves for its own use any environment variables that begin with the letters "RD", for example "RdRoleID". If your application creates environment variables that begin with "RD", in certain circumstances, the IsAvailable property will return false, and other methods and properties of the RoleEnvironment class will result in the error message "role discovery data is unavailable." To correct this, use environment variables that do not begin with the letters "RD".

noteNote
The RoleEnvironment class can be used on standalone components in an Azure VM outside of an Azure role. These components can be programs that can be run by, for example, remoting into the role instance and starting the component from the command line. These processes must be run with elevated privileges to access the RoleEnvironment class.

The following code example shows how to get and write out the value for a configuration setting called MySetting by using the GetConfigurationSettingValue method:


var settingValue = RoleEnvironment.GetConfigurationSettingValue("MySetting"); 
Trace.WriteLine("The setting value is: " + settingValue, "Information");

For more information about defining and configuring settings, see Windows Azure Service Configuration Schema and Windows Azure Service Definition Schema.

The following code example shows how to retrieve a local storage resource and write a text file to it:


// Retrieve an object that points to the local storage resource
LocalResource localResource = RoleEnvironment.GetLocalResource("localStoreTwo");

//Define the file name and path
string[] paths = { localResource.RootPath, "MyStorageTest.txt"};
String filePath = Path.Combine(paths);

using (FileStream writeStream = File.Create(filePath))
{
   Byte[] textToWrite = new UTF8Encoding(true).GetBytes("Testing Web role storage");
   writeStream.Write(textToWrite, 0, textToWrite.Length);
}

The following code example shows how to retrieve endpoint information for the current role instance:


var roleInstance = RoleEnvironment.CurrentRoleInstance; 
foreach (RoleInstanceEndpoint instanceEndpoint in roleInstance.InstanceEndpoints.Values) 
{  
   Trace.WriteLine("Instance endpoint address and port: " + instanceEndpoint.IPEndpoint, "Information");
   Trace.WriteLine("Protocol for the endpoint: " + , instanceEndpoint.Protocol, "Information");
}

The following code example shows how to retrieve the configuration changes that have been made to a role instance:


public override bool OnStart()
{
   RoleEnvironment.Changed += RoleEnvironmentChanged;
  
   return base.OnStart();
}
   
private void RoleEnvironmentChanged(object sender, RoleEnvironmentChangedEventArgs e)
{
   // Get the list of configuration changes
   var settingChanges = e.Changes.OfType<RoleEnvironmentConfigurationSettingChange>();
      
   foreach (var settingChange in settingChanges) 
   {
      var message = "Setting: " + settingChange.ConfigurationSettingName;
      Trace.WriteLine(message, "Information");
   }
}

The events are only raised if an internal endpoint is defined for the role in the ServiceDefinition.csdef file. For more information about defining endpoints, see How to Define Internal Endpoints for a Role.


System.Object
  Microsoft.WindowsAzure.ServiceRuntime.RoleEnvironment

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Development Platforms

Windows Vista, Windows 7, Windows Server 2008, Windows 8.1, Windows Server 2012 R2, Windows 8 and Windows Server 2012

Target Platforms

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