SASL Application — sasl v4.4

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# SASL Application

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## Description

The SASL application provides the following services:

- `alarm_handler`
- `release_handler`
- `systools`

#### Note

The SASL application in OTP has nothing to do with "Simple Authentication and Security Layer" (RFC 4422).

## Configuration

The following configuration parameters are defined for the SASL application. For more information about configuration parameters, see `app(4)` in Kernel.

All configuration parameters are optional.

- `start_prg = string()` - Specifies the program to be used when restarting the system during release installation. Default is `$OTPROOT/bin/start`.

- `masters = [atom()]` - Specifies the nodes used by this node to read/write release information. This parameter is ignored if parameter `client_directory` is not set.

- `client_directory = string()` - This parameter specifies the client directory at the master nodes. For details, see Release Handling in OTP Design Principles. This parameter is ignored if parameter `masters` is not set.

- `static_emulator = true | false` - Indicates if the Erlang emulator is statically installed. A node with a static emulator cannot switch dynamically to a new emulator, as the executable files are written into memory statically. This parameter is ignored if parameters `masters` and `client_directory` are not set.

- `releases_dir = string()` - Indicates where the `releases` directory is located. The release handler writes all its files to this directory. If this parameter is not set, the OS environment parameter `RELDIR` is used. By default, this is `$OTPROOT/releases`.

## Deprecated Error Logger Event Handlers and Configuration

In Erlang/OTP 21.0, a new API for logging was added. The old `error_logger` event manager, and event handlers running on this manager, still work, but they are not used by default.

The error logger event handlers `sasl_report_tty_h` and `sasl_report_file_h`, were earlier used for printing the so called SASL reports, that is, supervisor reports, crash reports, and progress reports. These reports are now also printed by the default logger handler started by the Kernel application. Progress reports are by default stopped by the primary log level, but can be enabled by setting this level to `info`, for example by using the Kernel configuration parameter `logger_level`.

If the old error logger event handlers are still desired, they must be added by calling `error_logger:add_report_handler/1,2`.

- `sasl_report_tty_h` - Formats and writes supervisor reports, crash reports, and progress reports to `stdio`. This error logger event handler uses `error_logger_format_depth` in the Kernel application to limit how much detail is printed in crash and supervisor reports.

- `sasl_report_file_h` - Formats and writes supervisor reports, crash report, and progress report to a single file. This error logger event handler uses `error_logger_format_depth` in the Kernel application to limit the details printed in crash and supervisor reports.

A similar behaviour, but still using the new logger API, can be obtained by setting the Kernel application environment variable `logger_sasl_compatible` to `true`. This adds a second instance of the standard Logger handler, named `sasl`, which only prints the SASL reports. No SASL reports are then printed by the Kernel logger handler.

The `sasl` handler is configured according to the values of the following SASL application environment variables.

- `sasl_error_logger = Value` - `Value` is one of the following:

  - `tty` - Installs `sasl_report_tty_h` in the error logger. This is the default option.

  - `{file,FileName}` - Installs `sasl_report_file_h` in the error logger. All reports go to file `FileName`, which is a string. The file is opened in `write` mode with encoding `utf8`.

  - `{file,FileName,Modes}` - Same as `{file,FileName}`, except that `Modes` allows you to specify the modes used for opening the `FileName` given to the `file:open/2` call. By default, the file is opened in `write` mode with encoding `utf8`. Use `[append]` to have the `FileName` open in append mode. A different encoding can also be specified. `FileName` is a string.

  - `false` - No SASL error logger handler is installed.

- `errlog_type = error | progress | all` - Restricts the error logging performed by the specified `sasl_error_logger` to error reports or progress reports, or both. Default is `all`.

- `utc_log = true | false` - If set to `true`, all dates in textual log outputs are displayed in Universal Coordinated Time with the string `UTC` appended.

The error logger event handler `log_mf_h` can also still be used. This event handler writes all events sent to the error logger to disk. Multiple files and log rotation are used. For efficiency reasons, each event is written as a binary. For more information about this handler, see the STDLIB Reference Manual.

To activate this event handler, three SASL configuration parameters must be set:

- `error_logger_mf_dir = string() | false` - Specifies in which directory `log_mf_h` is to store its files. If this parameter is undefined or `false`, the `log_mf_h` handler is not installed.

- `error_logger_mf_maxbytes = integer()` - Specifies the maximum size of each individual file written by `log_mf_h`. If this parameter is undefined, the `log_mf_h` handler is not installed.

- `error_logger_mf_maxfiles = 0<integer()<256` - Specifies the number of files used by `log_mf_h`. If this parameter is undefined, the `log_mf_h` handler is not installed.

The new `logger_disk_log_h` might be an alternative to `log_mf_h` if log rotation is desired. This does, however, write the log events in clear text and not as binaries.

## See Also

`alarm_handler`, `error_logger`, `logger`, `log_mf_h`, `rb`, `release_handler`, `systools`

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