Audit.NET

An extensible framework to audit executing operations in .NET including support for .NET Framework 4.5 and NetCore 1.0 (NetStandard 1.3).

Generate an audit log with evidence for reconstruction and examination of activities that have affected specific operations or procedures.

With Audit.NET you can generate tracking information about operations being executed. It will automatically log environmental information such as the caller user id, machine name, method name, exceptions, including the execution time and duration, exposing an extensible mechanism in which you can provide extra information or implement your output mechanism for the audit logs.

Extensions to log to Files, Event Log, SQL, MongoDB, AzureBlob and DocumentDB are provided. And also extensions to audit different systems such as EntityFramework, MVC, WebAPI and WCF. See Extensions section for more information.

Install

Nuget package

PM> Install-Package Audit.NET

Usage

Surround the operation code you want to audit with a using block that creates an AuditScope indicating the object to track (target).

Suppose you have the following code to cancel an order:

Order order = Db.GetOrder(orderId);
order.Status = -1;
order.OrderItems = null;
order = Db.OrderUpdate(order);

To audit this operation, tracking the Order object, you can add the following using statement:

Order order = Db.GetOrder(orderId);
using (AuditScope.Create("Order:Update", () => order))
{
    order.Status = -1;
    order.OrderItems = null;
    order = Db.OrderUpdate(order);
}

It is not mandatory to use a using block, but it simplifies the syntax allowing to detect exceptions and calculate the duration by implicitly saving the event on disposal.

The first parameter of the Create method is an event type name intended to identify and group the events. The second is the delegate to obtain the object to track (target object). This object is passed as a Func<object> to allow the library inspect the value at the beggining and at the end of the scope. It is not mandatory to supply a target object, pass null when you don't want to track a specific object.

If you are not tracking an object, nor the duration of an event, you can use the CreateAndSave shortcut method that logs an event immediately. For example:

AuditScope.CreateAndSave("Event Type", new { ExtraField = "extra value" });

The library will generate an output (AuditEvent) for each operation, including:

Tracked object's state before and after the operation.
Execution time and duration.
Environment information such as user, machine, domain, locale, etc.
Comments and Custom Fields provided

An example of the output in JSON:

{
	"EventType": "Order:Update",
	"Environment": {
		"UserName": "Federico",
		"MachineName": "HP",
		"DomainName": "HP",
		"CallingMethodName": "Audit.UnitTest.AuditTests.TestUpdate()",
		"Exception": null,
		"Culture": "en-GB"
	},
	"StartDate": "2016-08-23T11:33:14.653191-05:00",
	"EndDate": "2016-08-23T11:33:23.1820786-05:00",
	"Duration": 8529,
	"Target": {
		"Type": "Order",
		"Old": {
			"OrderId": "39dc0d86-d5fc-4d2e-b918-fb1a97710c99",
			"Status": 2,
			"OrderItems": [{
				"Sku": "1002",
				"Quantity": 3.0
			}]
		},
		"New": {
			"OrderId": "39dc0d86-d5fc-4d2e-b918-fb1a97710c99",
			"Status": -1,
			"OrderItems": null
		}
	}
}

Output details

The following tables describes the output fields:

AuditEvent object

Field Name	Type	Description
EventType	string	User-defined string to group the events
Environment	Environment	Contains information about the execution environment
StartDate	DateTime	Date and time when the event has started
EndDate	DateTime	Date and time when the event has ended
Duration	integer	Duration of the event in milliseconds
Target	Target	User-defined tracked object
Comments	Array of strings	User-defined comments

Environment object

Field Name	Type	Description
UserName	string	Current logged user name
MachineName	string	Executing machine name
DomainName	string	Current user domain
CallingMethodName	string	Calling method signature information
Exception	string	Indicates if an Exception has been detected (NULL if no exception has been thrown)
Culture	string	Current culture identifier

Target object

Field Name	Type	Description
Type	string	Tracked object type name
Old	Object	Value of the tracked object at the beginning of the event
New	Object	Value of the tracked object at the end of the event

Custom Fields and Comments

The AuditScope object provides two methods to extend the event output.

With SetCustomField() you can store any object as a custom field.
With Comment() you can add textual comments to the event.

For example:

Order order = Db.GetOrder(orderId);
using (var audit = AuditScope.Create("Order:Update", () => order))
{
    audit.SetCustomField("ReferenceId", orderId);
    order.Status = -1;
    order = Db.OrderUpdate(order);
    audit.Comment("Status Updated to Cancelled");
}

The output of the previous example would be:

{
	"EventType": "Order:Update",
	"Environment": {
		"UserName": "Federico",
		"MachineName": "HP",
		"DomainName": "HP",
		"CallingMethodName": "Audit.UnitTest.AuditTests.TestUpdate()",
		"Exception": null,
		"Culture": "en-GB"
	},
	"Target": {
		"Type": "Order",
		"Old": {
			"OrderId": "39dc0d86-d5fc-4d2e-b918-fb1a97710c99",
			"Status": 2,
			
		},
		"New": {
			"OrderId": "39dc0d86-d5fc-4d2e-b918-fb1a97710c99",
			"Status": -1,
			
		}
	},
	"ReferenceId": "39dc0d86-d5fc-4d2e-b918-fb1a97710c99",           // <-- Custom Field
	"Comments": ["Status Updated to Cancelled"],                     // <-- Comments
	"StartDate": "2016-08-23T11:34:44.656101-05:00",
	"EndDate": "2016-08-23T11:34:55.1810821-05:00",
	"Duration": 8531
}

You can also set Custom Fields when creating the AuditScope, by passing an anonymous object with the properties you want as extra fields. For example:

using (var audit = AuditScope.Create("Order:Update", () => order, new { ReferenceId = orderId }))
{
    order.Status = -1;
    order = Db.OrderUpdate(order);
    audit.Comment("Status Updated to Cancelled");
}

##Discard option

The AuditScope object has a Discard() method to allow the user to discard an event under certain condition.

For example, if you want to avoid saving the audit event when an exception is thrown:

using (var scope = AuditScope.Create("SomeEvent", () => someTarget))
{
    try
    {
        //some operation
        Critical.Operation();
    }
    catch (Exception ex)
    {
        //If an exception is thown, discard the audit event
        scope.Discard();
    }
}

Event output

You decide what to do with the events by configuring one of the mechanisms provided (File, EventLog, MongoDB, SQL, DocumentDB, AzureBlobStorage) or by injecting your own mechanism, creating a class that inherits from AuditDataProvider, for example:

public class MyFileDataProvider : AuditDataProvider
{
    public override object InsertEvent(AuditEvent auditEvent)
    {
        // AuditEvent provides a ToJson() method
        string json = auditEvent.ToJson();
        // Write the json representation of the event to a randomly named file
        var fileName = "Log" + Guid.NewGuid().ToString() + ".json";
        File.WriteAllText(fileName, json);
        return fileName;
    }
    // Update an existing event given the ID and the event
    public override void ReplaceEvent(object eventId, AuditEvent auditEvent)
    {
        // Override an existing event
        var fileName = eventId.ToString();
        File.WriteAllText(fileName, auditEvent.ToJson());
    }
}

The InsertEvent method should return a unique ID for the event. The ReplaceEvent method should update an event given its ID, this method is only called when the Creation Policy is set to Manual or InsertOnStartReplaceOnEnd.

Event Creation Policy

The audit scope can be configured to persist the event in different ways:

Insert on End: (default) The audit event is saved when the scope is disposed.
Insert on Start, Replace on End: The event (on its initial state) is saved when the scope is created, and then the complete event information is updated when the scope is disposed.
Insert on Start, Insert on End: Two versions of the event are saved, the initial when the scope is created, and the final when the scope is disposed.
Manual: The event saving (insert/replace) should be explicitly invoked by calling the Save() method on the AuditScope.

You can set the Creation Policy per-scope, for example to explicitly set the Creation Policy to Manual:

using (var scope = AuditScope.Create("MyEvent", () => target, EventCreationPolicy.Manual))
{
    //...
    scope.Save();
}

If you don't provide a Creation Policy, the default Creation Policy configured will be used (see next section).

Configuration

Data provider

To change the default data provider, set the static property DataProvider on Audit.Core.Configuration class. This should be done prior to the AuditScope creation, i.e. during application startup.

For example, to set your own provider as the default data provider:

Audit.Core.Configuration.DataProvider = new MyFileDataProvider();

Creation Policy

To change the default creation policy, set the static property SetCreationPolicy on Audit.Core.Configuration class. This should be done prior to the AuditScope creation, i.e. during application startup.

For example, to set the default creation policy to Manual:

Audit.Core.Configuration.CreationPolicy = EventCreationPolicy.Manual;

Custom Actions

You can configure Custom Actions that are executed for all the Audit Scopes in your application. This allows to globally change the behavior and data, intercepting the scopes after they are created or before they are saved.

Call the static AddCustomAction() method on Audit.Core.Configuration class to attach a custom action.

For example, to globally discard the events under centain condition:

Audit.Core.Configuration.AddCustomAction(ActionType.OnScopeCreated, scope =>
{
    if (DateTime.Now.Hour == 17) // Tea time
    {
        scope.Discard();
    }
});

Or to add custom fields / comments globally to all scopes:

Audit.Core.Configuration.AddCustomAction(ActionType.OnEventSaving, scope =>
{
    if (scope.Event.Environment.Exception != null)
    {
        scope.SetCustomField("Oops", true);
    }
    scope.Comment("Saved at " + DateTime.Now);
});

The ActionType indicates when to perform the action. The allowed values are:

OnScopeCreated: When the Audit Scope is being created, before any saving. This is executed once per Audit Scope.
OnEventSaving: When an Audit Scope's Event is about to be saved.

Configuration Fluent API

Alternatively to the properties/methods mentioned before, you can configure the library using a convenient Fluent API provided by the method Audit.Core.Configuration.Setup(), this is the most straightforward way to configure the library.

For example, to set the FileLog Provider with its default settings using a Manual creation policy:

Audit.Core.Configuration.Setup()
    .UseFileLogProvider()
    .WithCreationPolicy(EventCreationPolicy.Manual);

Configuration examples

File log provider with an InsertOnStart-ReplaceOnEnd creation policy, and a global ApplicationId Custom Field:

Audit.Core.Configuration.DataProvider = new FileDataProvider()
{
    FilenamePrefix = "Event_",
    DirectoryPath = @"C:\AuditLogs\1"
};

Audit.Core.Configuration.CreationPolicy = EventCreationPolicy.InsertOnStartReplaceOnEnd;

Audit.Core.Configuration.AddCustomAction(ActionType.OnScopeCreated, scope => 
{ 
    scope.SetCustomField("ApplicationId", "MyApplication"); 
});

Or by using the fluent API:

Audit.Core.Configuration.Setup()
    .UseFileLogProvider(config => config
        .FilenamePrefix("Event_")
        .Directory(@"C:\AuditLogs\1"))
    .WithCreationPolicy(EventCreationPolicy.InsertOnStartReplaceOnEnd)
    .WithAction(x => x.OnScopeCreated(scope => scope.SetCustomField("ApplicationId", "MyApplication")));

File log provider with dynamic directory path and filename (fluent API):

Audit.Core.Configuration.Setup()
    .UseFileLogProvider(config => config
        .DirectoryBuilder(_ => $@"C:\Logs\{DateTime.Now:yyyy-MM-dd}")
        .FilenameBuilder(auditEvent => $"{auditEvent.Environment.UserName}_{DateTime.Now.Ticks}.json"));

Event log provider with an InsertOnEnd creation policy (fluent API):

Audit.Core.Configuration.Setup()
    .UseEventLogProvider(config => config
        .SourcePath("My Audited Application")
        .LogName("Application"))
    .WithCreationPolicy(EventCreationPolicy.InsertOnEnd);

Extensions

The following packages are extensions to log interactions with different systems such as MVC, WebApi, WCF and Entity Framework:

Audit.WCF

Generate detailed server-side audit logs for Windows Communication Foundation (WCF) service calls, by configuring a provided behavior.

Audit.EntityFramework

Generate detailed audit logs for CRUD operations on Entity Framework, by inheriting from a provided DbContext. Includes support for EF 6 and EF 7 (EF Core).