Add default storage location

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/api/Azure.Monitor.OpenTelemetry.Exporter.netstandard2.0.cs

@@ -8,6 +8,7 @@ public partial class AzureMonitorExporterOptions : Azure.Core.ClientOptions
     {
         public AzureMonitorExporterOptions(Azure.Monitor.OpenTelemetry.Exporter.AzureMonitorExporterOptions.ServiceVersion version = Azure.Monitor.OpenTelemetry.Exporter.AzureMonitorExporterOptions.ServiceVersion.V2020_09_15_Preview) { }
         public string ConnectionString { get { throw null; } set { } }
+        public string StorageDirectory { get { throw null; } set { } }
         public Azure.Monitor.OpenTelemetry.Exporter.AzureMonitorExporterOptions.ServiceVersion Version { get { throw null; } set { } }
         public enum ServiceVersion
         {

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/AzureMonitorExporterHelperExtensions.cs

@@ -29,6 +29,11 @@ public static TracerProviderBuilder AddAzureMonitorTraceExporter(this TracerProv
             var options = new AzureMonitorExporterOptions();
             configure?.Invoke(options);
 
+            if (options.StorageDirectory == null)
+            {
+                options.StorageDirectory = StorageHelper.GetDefaultStorageDirectory();
+            }
+
             // TODO: Pick Simple vs Batching based on AzureMonitorExporterOptions
             return builder.AddProcessor(new BatchActivityExportProcessor(new AzureMonitorTraceExporter(options)));
         }

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/AzureMonitorExporterOptions.cs

@@ -47,5 +47,7 @@ public enum ServiceVersion
             /// </summary>
             V2020_09_15_Preview = 1,
         }
+
+        public string StorageDirectory { get; set; }
     }
 }

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/StorageHelper.cs

@@ -0,0 +1,114 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections;
+using System.IO;
+using System.Runtime.InteropServices;
+
+namespace Azure.Monitor.OpenTelemetry.Exporter
+{
+    internal static class StorageHelper
+    {
+        private static string defaultStorageDirectory;
+        private const string nonWindowsVarTmp = "/var/tmp/";
+        private const string nonWindowsTmp = "/tmp/";
+
+        internal static string GetDefaultStorageDirectory()
+        {
+            if (defaultStorageDirectory != null)
+            {
+                return defaultStorageDirectory;
+            }
+            else
+            {
+                string dirPath;
+                IDictionary environmentVars = Environment.GetEnvironmentVariables();
+
+                if (IsWindowsOS())
+                {
+                    string localAppData = environmentVars["LOCALAPPDATA"].ToString();
+                    if (localAppData != null)
+                    {
+                        dirPath = CreateTelemetryDirectory(localAppData);
+                        if (dirPath != null)
+                        {
+                            defaultStorageDirectory = dirPath;
+                            return defaultStorageDirectory;
+                        }
+
+                        string temp = environmentVars["TEMP"].ToString();
+                        if (temp != null)
+                        {
+                            dirPath = CreateTelemetryDirectory(temp);
+                            if (dirPath != null)
+                            {
+                                defaultStorageDirectory = dirPath;
+                                return defaultStorageDirectory;
+                            }
+                        }
+                    }
+                }
+                else
+                {
+                    string tmpdir = environmentVars["TMPDIR"].ToString();
+                    if (tmpdir != null)
+                    {
+                        dirPath = CreateTelemetryDirectory(tmpdir);
+                        if (dirPath != null)
+                        {
+                            defaultStorageDirectory = dirPath;
+                            return defaultStorageDirectory;
+                        }
+                    }
+
+                    dirPath = CreateTelemetryDirectory(nonWindowsVarTmp);
+                    if (dirPath != null)
+                    {
+                        defaultStorageDirectory = dirPath;
+                        return defaultStorageDirectory;
+                    }
+
+                    dirPath = CreateTelemetryDirectory(nonWindowsTmp);
+                    if (dirPath != null)
+                    {
+                        defaultStorageDirectory = dirPath;
+                        return defaultStorageDirectory;
+                    }
+                }
+
+                return defaultStorageDirectory;
+            }
+        }
+
+        /// <summary>
+        /// Creates directory for storing telemetry.
+        /// </summary>
+        /// <param name="path">Base directory.</param>
+        /// <returns>Directory path if it is created else null.</returns>
+        private static string CreateTelemetryDirectory(string path)
+        {
+            try
+            {
+                string telemetryDirPath = Path.Combine(path, "Microsoft", "ApplicationInsights");
+                Directory.CreateDirectory(telemetryDirPath);
+                return telemetryDirPath;
+            }
+            catch (Exception ex)
+            {
+                AzureMonitorExporterEventSource.Log.Write($"ErrorCreatingDefaultStorageFolder{EventLevelSuffix.Error}", $"{ex.ToInvariantString()}");
+                return null;
+            }
+        }
+
+        internal static bool IsWindowsOS()
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                return true;
+            }
+
+            return false;
+        }
+    }
+}