6.4.4.6 Audit Log Reference

The following discussion serves as a reference to MySQL Enterprise Audit components:

• Audit Log Option and Variable Reference

• Audit Log Options and System Variables

• Audit Log Plugin Status Variables

Audit Log Option and Variable Reference

Table 6.16 Audit Log Option and Variable Reference

Name	Cmd-Line	Option File	System Var	Status Var	Var Scope	Dynamic
audit-log	Yes	Yes
audit_log_buffer_size	Yes	Yes	Yes		Global	No
audit_log_connection_policy	Yes	Yes	Yes		Global	Yes
audit_log_current_session			Yes		Both	No
Audit_log_current_size				Yes	Global	No
Audit_log_event_max_drop_size				Yes	Global	No
Audit_log_events				Yes	Global	No
Audit_log_events_filtered				Yes	Global	No
Audit_log_events_lost				Yes	Global	No
Audit_log_events_written				Yes	Global	No
audit_log_exclude_accounts	Yes	Yes	Yes		Global	Yes
audit_log_file	Yes	Yes	Yes		Global	No
audit_log_flush			Yes		Global	Yes
audit_log_format	Yes	Yes	Yes		Global	No
audit_log_include_accounts	Yes	Yes	Yes		Global	Yes
audit_log_policy	Yes	Yes	Yes		Global	Varies
audit_log_rotate_on_size	Yes	Yes	Yes		Global	Yes
audit_log_statement_policy	Yes	Yes	Yes		Global	Yes
audit_log_strategy	Yes	Yes	Yes		Global	No
Audit_log_total_size				Yes	Global	No
Audit_log_write_waits				Yes	Global	No

Audit Log Options and System Variables

This section describes the command options and system variables that control operation of MySQL Enterprise Audit. If values specified at startup time are incorrect, the audit log plugin may fail to initialize properly and the server does not load it. In this case, the server may also produce error messages for other audit log settings because it will not recognize them.

To control activation of the audit log plugin, use this option:

• --audit-log[=value]

  Property	Value
  Command-Line Format	--audit-log[=value]
  Type	Enumeration
  Default Value	ON
  Valid Values	ON OFF FORCE FORCE_PLUS_PERMANENT

  This option controls how the server loads the audit_log plugin at startup. It is available only if the plugin has been previously registered with INSTALL PLUGIN or is loaded with --plugin-load or --plugin-load-add. See Section 6.4.4.1, “Installing MySQL Enterprise Audit”.

  The option value should be one of those available for plugin-loading options, as described in Section 5.5.1, “Installing and Uninstalling Plugins”. For example, --audit-log=FORCE_PLUS_PERMANENT tells the server to load the plugin at startup and prevents it from being removed while the server is running.

If the audit log plugin is enabled, it exposes several system variables that permit control over logging:

mysql> SHOW VARIABLES LIKE 'audit_log%';
+-----------------------------+--------------+
| Variable_name               | Value        |
+-----------------------------+--------------+
| audit_log_buffer_size       | 1048576      |
| audit_log_connection_policy | ALL          |
| audit_log_current_session   | ON           |
| audit_log_exclude_accounts  |              |
| audit_log_file              | audit.log    |
| audit_log_flush             | OFF          |
| audit_log_format            | OLD          |
| audit_log_include_accounts  |              |
| audit_log_policy            | ALL          |
| audit_log_rotate_on_size    | 0            |
| audit_log_statement_policy  | ALL          |
| audit_log_strategy          | ASYNCHRONOUS |
+-----------------------------+--------------+

You can set any of these variables at server startup, and some of them at runtime.

• audit_log_buffer_size

  Property	Value
  Command-Line Format	--audit-log-buffer-size=#
  System Variable	audit_log_buffer_size
  Scope	Global
  Dynamic	No
  Type	Integer
  Default Value	1048576
  Minimum Value	4096
  Maximum Value (64-bit platforms)	18446744073709547520
  Maximum Value (32-bit platforms)	4294967295

  When the audit log plugin writes events to the log asynchronously, it uses a buffer to store event contents prior to writing them. This variable controls the size of that buffer, in bytes. The server adjusts the value to a multiple of 4096. The plugin uses a single buffer, which it allocates when it initializes and removes when it terminates. The plugin allocates this buffer only if logging is asynchronous.

• audit_log_connection_policy

  Property	Value
  Command-Line Format	--audit-log-connection-policy=value
  Introduced	5.6.20
  System Variable	audit_log_connection_policy
  Scope	Global
  Dynamic	Yes
  Type	Enumeration
  Default Value	ALL
  Valid Values	ALL ERRORS NONE

  The policy controlling how the audit log plugin writes connection events to its log file. The following table shows the permitted values.

  Value	Description
  ALL	Log all connection events
  ERRORS	Log only failed connection events
  NONE	Do not log connection events

  Note

  At server startup, any explicit value given for audit_log_connection_policy may be overridden if audit_log_policy is also specified, as described in Section 6.4.4.4, “Audit Log Logging Control”.

• audit_log_current_session

  Property	Value
  Introduced	5.6.20
  System Variable	audit_log_current_session
  Scope	Global, Session
  Dynamic	No
  Type	Boolean
  Default Value	depends on filtering policy

  Whether audit logging is enabled for the current session. The session value of this variable is read only. It is set when the session begins based on the values of the audit_log_include_accounts and audit_log_exclude_accounts system variables. The audit log plugin uses the session value to determine whether to audit events for the session. (There is a global value, but the plugin does not use it.)

• audit_log_exclude_accounts

  Property	Value
  Command-Line Format	--audit-log-exclude-accounts=value
  Introduced	5.6.20
  System Variable	audit_log_exclude_accounts
  Scope	Global
  Dynamic	Yes
  Type	String
  Default Value	NULL

  The accounts for which events should not be logged. The value should be NULL or a string containing a list of one or more comma-separated account names. For more information, see Section 6.4.4.5, “Audit Log Filtering”.

  Modifications to audit_log_exclude_accounts affect only connections created subsequent to the modification, not existing connections.

• audit_log_file

  Property	Value
  Command-Line Format	--audit-log-file=file_name
  System Variable	audit_log_file
  Scope	Global
  Dynamic	No
  Type	File name
  Default Value	audit.log

  The name of the file to which the audit log plugin writes events. The default value is audit.log. If the value of audit_log_file is a relative path name, the plugin interprets it relative to the data directory. If the value is a full path name, the plugin uses the value as is. A full path name may be useful if it is desirable to locate audit files on a separate file system or directory. For security reasons, the audit log file should be written to a directory accessible only to the MySQL server and to users with a legitimate reason to view the log. For more information, see Section 6.4.4.4, “Audit Log Logging Control”.

• audit_log_flush

  Property	Value
  System Variable	audit_log_flush
  Scope	Global
  Dynamic	Yes
  Type	Boolean
  Default Value	OFF

  When this variable is set to enabled (1 or ON), the audit log plugin closes and reopens its log file to flush it. (The value remains OFF so that you need not disable it explicitly before enabling it again to perform another flush.) Enabling this variable has no effect unless audit_log_rotate_on_size is 0. For more information, see Section 6.4.4.4, “Audit Log Logging Control”.

• audit_log_format

  Property	Value
  Command-Line Format	--audit-log-format=value
  Introduced	5.6.14
  System Variable	audit_log_format
  Scope	Global
  Dynamic	No
  Type	Enumeration
  Default Value	OLD
  Valid Values	OLD NEW

  The audit log file format. Permitted values are OLD and NEW (default OLD). For details about each format, see Section 6.4.4.3, “Audit Log File Formats”.

  Note

  Changing the value of audit_log_format can result in writing log entries in one format to an existing log file that contains entries in a different format. To avoid this issue, use the procedure described at Audit Log File Format.

• audit_log_include_accounts

  Property	Value
  Command-Line Format	--audit-log-include-accounts=value
  Introduced	5.6.20
  System Variable	audit_log_include_accounts
  Scope	Global
  Dynamic	Yes
  Type	String
  Default Value	NULL

  The accounts for which events should be logged. The value should be NULL or a string containing a list of one or more comma-separated account names. For more information, see Section 6.4.4.5, “Audit Log Filtering”.

  Modifications to audit_log_include_accounts affect only connections created subsequent to the modification, not existing connections.

• audit_log_policy

  Property	Value
  Command-Line Format	--audit-log-policy=value
  System Variable	audit_log_policy
  Scope	Global
  Dynamic (≥ 5.6.20)	No
  Dynamic (≤ 5.6.19)	Yes
  Type	Enumeration
  Default Value	ALL
  Valid Values	ALL LOGINS QUERIES NONE

  The policy controlling how the audit log plugin writes events to its log file. The following table shows the permitted values.

  Value	Description
  ALL	Log all events
  LOGINS	Log only login events
  QUERIES	Log only query events
  NONE	Log nothing (disable the audit stream)

  As of MySQL 5.6.20, audit_log_policy can be set only at server startup. At runtime, it is a read-only variable. This is due to the introduction of two other system variables, audit_log_connection_policy and audit_log_statement_policy, that provide finer control over logging policy and that can be set either at startup or at runtime. If you continue to use audit_log_policy at startup instead of the other two variables, the server uses its value to set those variables. For more information about the policy variables and their interaction, see Section 6.4.4.4, “Audit Log Logging Control”.

  Before MySQL 5.6.20, the audit_log_connection_policy and audit_log_statement_policy system variables do not exist. audit_log_policy is the only policy control variable and it can be set at server startup or runtime.

• audit_log_rotate_on_size

  Property	Value
  Command-Line Format	--audit-log-rotate-on-size=#
  System Variable	audit_log_rotate_on_size
  Scope	Global
  Dynamic	Yes
  Type	Integer
  Default Value	0

  If the audit_log_rotate_on_size value is 0, the audit log plugin does not perform automatic log file rotation. Instead, use audit_log_flush to close and reopen the log on demand. In this case, manually rename the file externally to the server before flushing it.

  If the audit_log_rotate_on_size value is greater than 0, automatic size-based log file rotation occurs. Whenever a write to the log file causes its size to exceed the audit_log_rotate_on_size value, the audit log plugin closes the current log file, renames it, and opens a new log file.

  For more information about audit log file rotation, see Audit Log File Space Management and Name Rotation.

  If you set this variable to a value that is not a multiple of 4096, it is truncated to the nearest multiple. (Thus, setting it to a value less than 4096 has the effect of setting it to 0 and no rotation occurs, except manually.)

• audit_log_statement_policy

  Property	Value
  Command-Line Format	--audit-log-statement-policy=value
  Introduced	5.6.20
  System Variable	audit_log_statement_policy
  Scope	Global
  Dynamic	Yes
  Type	Enumeration
  Default Value	ALL
  Valid Values	ALL ERRORS NONE

  The policy controlling how the audit log plugin writes statement events to its log file. The following table shows the permitted values.

  Value	Description
  ALL	Log all statement events
  ERRORS	Log only failed statement events
  NONE	Do not log statement events

  Note

  At server startup, any explicit value given for audit_log_statement_policy may be overridden if audit_log_policy is also specified, as described in Section 6.4.4.4, “Audit Log Logging Control”.

• audit_log_strategy

  Property	Value
  Command-Line Format	--audit-log-strategy=value
  System Variable	audit_log_strategy
  Scope	Global
  Dynamic	No
  Type	Enumeration
  Default Value	ASYNCHRONOUS
  Valid Values	ASYNCHRONOUS PERFORMANCE SEMISYNCHRONOUS SYNCHRONOUS

  The logging method used by the audit log plugin. These strategy values are permitted:

  • ASYNCHRONOUS: Log asynchronously. Wait for space in the output buffer.

  • PERFORMANCE: Log asynchronously. Drop requests for which there is insufficient space in the output buffer.

  • SEMISYNCHRONOUS: Log synchronously. Permit caching by the operating system.

  • SYNCHRONOUS: Log synchronously. Call sync() after each request.

Audit Log Plugin Status Variables

If the audit log plugin is enabled, it exposes several status variables that provide operational information.

• Audit_log_current_size

  The size of the current audit log file. The value increases when an event is written to the log and is reset to 0 when the log is rotated.

• Audit_log_event_max_drop_size

  The size of the largest dropped event in performance logging mode. For a description of logging modes, see Section 6.4.4.4, “Audit Log Logging Control”.

• Audit_log_events

  The number of events handled by the audit log plugin, whether or not they were written to the log based on filtering policy (see Section 6.4.4.4, “Audit Log Logging Control”).

• Audit_log_events_filtered

  The number of events handled by the audit log plugin that were filtered (not written to the log) based on filtering policy (see Section 6.4.4.4, “Audit Log Logging Control”).

• Audit_log_events_lost

  The number of events lost in performance logging mode because an event was larger than than the available audit log buffer space. This value may be useful for assessing how to set audit_log_buffer_size to size the buffer for performance mode. For a description of logging modes, see Section 6.4.4.4, “Audit Log Logging Control”.

• Audit_log_events_written

  The number of events written to the audit log.

• Audit_log_total_size

  The total size of events written to all audit log files. Unlike Audit_log_current_size, the value of Audit_log_total_size increases even when the log is rotated.

• Audit_log_write_waits

  The number of times an event had to wait for space in the audit log buffer in asynchronous logging mode. For a description of logging modes, see Section 6.4.4.4, “Audit Log Logging Control”.