debian-mirror-gitlab/doc/development/audit_event_guide/index.md

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Audit Event Guide

This guide provides an overview of how Audit Events work, and how to instrument new audit events.

What are Audit Events?

Audit Events are a tool for GitLab owners and administrators to view records of important actions performed across the application.

Audit Event Schemas

To instrument an audit event, the following attributes should be provided:

Attribute	Type	Required?	Description
name	String	false	Action name to be audited. Used for error tracking
author	User	true	User who authors the change
scope	User, Project, Group	true	Scope which the audit event belongs to
target	Object	true	Target object being audited
message	String	true	Message describing the action

How to instrument new Audit Events

There are three ways of instrumenting audit events:

• Create a new class in ee/lib/ee/audit/ and extend AuditEventService
• Call AuditEventService after a successful action
• Call Gitlab::Audit::Auditor.audit passing an action block

This inconsistency leads to unexpected bugs, increases maintainer effort, and worsens the developer experience. Therefore, we suggest you use Gitlab::Audit::Auditor to instrument new audit events.

With new service, we can instrument audit events in two ways:

• Using block for multiple events.
• Using standard method call for single events.

Using block to record multiple events

This method is useful when events are emitted deep in the call stack.

For example, we can record multiple audit events when the user updates a merge request approval rule. As part of this user flow, we would like to audit changes to both approvers and approval groups. In the initiating service (for example, MergeRequestRuleUpdateService), we can wrap the execute call as follows:

# in the initiating service
audit_context = {
  name: 'update_merge_approval_rule',
  author: current_user,
  scope: project_alpha,
  target: merge_approval_rule,
  message: 'Attempted to update an approval rule'
}

::Gitlab::Audit::Auditor.audit(audit_context) do
  service.execute
end

In the model (for example, ApprovalProjectRule), we can push audit events on model callbacks (for example, after_save or after_add).

# in the model
include Auditable

def audit_add(model)
  push_audit_event('Added an approver on Security rule')
end

def audit_remove(model)
  push_audit_event('Removed an approver on Security rule')
end

This method does not support actions that are asynchronous, or span across multiple processes (for example, background jobs).

Using standard method call to record single event

This method allows recording single audit event and involves fewer moving parts.

if merge_approval_rule.save
  audit_context = {
    name: 'create_merge_approval_rule',
    author: current_user,
    scope: project_alpha,
    target: merge_approval_rule,
    message: 'Created a new approval rule'
  }

  ::Gitlab::Audit::Auditor.audit(audit_context)
end

Audit Event instrumentation flows

The two ways we can instrument audit events have different flows.

Using block to record multiple events

We wrap the operation block in a Gitlab::Audit::Auditor which captures the initial audit context (that is, author, scope, target) object that are available at the time the operation is initiated.

Extra instrumentation is required in the interacted classes in the chain with Auditable mixin to add audit events to the Audit Event queue via Gitlab::Audit::EventQueue.

The EventQueue is stored in a local thread via SafeRequestStore and then later extracted when we record an audit event in Gitlab::Audit::Auditor.

skinparam shadowing false
skinparam BoxPadding 10
skinparam ParticipantPadding 20

participant "Instrumented Class" as A
participant "Audit::Auditor" as A1 #LightBlue
participant "Audit::EventQueue" as B #LightBlue
participant "Interacted Class" as C
participant "AuditEvent" as D

A->A1: audit <b>{ block }
activate A1
A1->B: begin!
A1->C: <b>block.call
activate A1 #FFBBBB
activate C
C-->B: push [ message ]
C-->A1: true
deactivate A1
deactivate C
A1->B: read
activate A1 #FFBBBB
activate B
B-->A1: [ messages ]
deactivate B
A1->D: bulk_insert!
deactivate A1
A1->B: end!
A1-->A:
deactivate A1

Using standard method call to record single event

This method has a more straight-forward flow, and does not rely on EventQueue and local thread.

skinparam shadowing false
skinparam BoxPadding 10
skinparam ParticipantPadding 20

participant "Instrumented Class" as A
participant "Audit::Auditor" as B #LightBlue
participant "AuditEvent" as C

A->B: audit
activate B
B->C: bulk_insert!
B-->A:
deactivate B

In addition to recording to the database, we also write these events to a log file.