Errors & Logging

Question 1

What is the name of the class where all exceptions are triggered by your application, logged and then rendered back to the user?

Answer 1

The App\Exceptions\Handler

Question 2

For logging, Laravel utilizes what library, which provides support for a variety of powerful log handlers?

Answer 2

The Monolog library

Question 3

What is the purpose of the APP_DEBUG environment variable?

Answer 3

The debug option in your config/app.php configuration file determines how much information about an error is actually displayed to the user. By default, this option is set to respect the value of the APP_DEBUG environment variable, which is stored in your .env file.

For local development, you should set the APP_DEBUG environment variable to true. In your production environment, this value should always be false. If the value is set to true in production, you risk exposing sensitive configuration values to your application’s end users.

Question 4

Out of the box, Laravel supports writing log information to which files?

Answer 4

Out of the box, Laravel supports writing log information to single files, daily files, the syslog, and the errorlog. To configure which storage mechanism Laravel uses, you should modify the log option in your config/app.php configuration file. For example, if you wish to use daily log files instead of a single file, you should set the log value in your app configuration file to daily:

‘log’ => ‘daily

Question 5

What is the purpose of the log_max_files config option?

Answer 5

When using the daily log mode, Laravel will only retain five days of log files by default. If you want to adjust the number of retained files, you may add a log_max_files configuration value to your app configuration file:

‘log_max_files’ => 30

Question 6

What are the severity levels recognized by Monolog?

Answer 6

Monolog recognizes the following severity levels - from least severe to most severe: debug, info, notice, warning, error, critical, alert, emergency.

Question 7

What is the purpose of the log_level config option?

Answer 7

When using Monolog, log messages may have different levels of severity. By default, Laravel writes all log levels to storage. However, in your production environment, you may wish to configure the minimum severity that should be logged by adding the log_level option to your app.php configuration file.

Once this option has been configured, Laravel will log all levels greater than or equal to the specified severity. For example, a default log_level of error will log error, critical, alert, and emergency messages:

‘log_level’ => env(‘APP_LOG_LEVEL’, ‘error’),

Question 8

What is the purpose of the configureMonologUsing method?

Answer 8

If you would like to have complete control over how Monolog is configured for your application, you may use the application’s configureMonologUsing method. You should place a call to this method in your bootstrap/app.php file right before the $app variable is returned by the file:

$app->configureMonologUsing(function ($monolog) {
$monolog->pushHandler(…);
});

return $app;

Question 9

The App\Exceptions\Handler class contains what two methods?

Answer 9

report and render

Question 10

What is the purpose of the report method?

Answer 10

The report method is used to log exceptions or send them to an external service like Bugsnag or Sentry. By default, the report method simply passes the exception to the base class where the exception is logged.

If you need to report different types of exceptions in different ways, you may use the PHP instanceof comparison operator:

/**
 * Report or log an exception.
 *
 * This is a great spot to send exceptions to Sentry, Bugsnag, etc.
 *
 * @param  \Exception  $exception
 * @return void
 */
public function report(Exception $exception)
{
    if ($exception instanceof CustomException) {
        //
    }

return parent::report($exception); }

Question 11

What is the purpose of the dontReport property?

Answer 11

The $dontReport property of the exception handler contains an array of exception types that will not be logged. For example, exceptions resulting from 404 errors, as well as several other types of errors, are not written to your log files. You may add other exception types to this array as needed:

/**
 * A list of the exception types that should not be reported.
 *
 * @var array
 */
protected $dontReport = [
    \Illuminate\Auth\AuthenticationException::class,
    \Illuminate\Auth\Access\AuthorizationException::class,
    \Symfony\Component\HttpKernel\Exception\HttpException::class,
    \Illuminate\Database\Eloquent\ModelNotFoundException::class,
    \Illuminate\Validation\ValidationException::class,
];

Question 12

What is the purpose of the render method?

Answer 12

The render method is responsible for converting a given exception into an HTTP response that should be sent back to the browser. By default, the exception is passed to the base class which generates a response for you. However, you are free to check the exception type or return your own custom response:

/**
 * Render an exception into an HTTP response.
 *
 * @param  \Illuminate\Http\Request  $request
 * @param  \Exception  $exception
 * @return \Illuminate\Http\Response
 */
public function render($request, Exception $exception)
{
    if ($exception instanceof CustomException) {
        return response()->view('errors.custom', [], 500);
    }

return parent::render($request, $exception); }

Question 13

What is the purpose of the abort helper method?

Answer 13

Some exceptions describe HTTP error codes from the server. For example, this may be a “page not found” error (404), an “unauthorized error” (401) or even a developer generated 500 error. In order to generate such a response from anywhere in your application, you may use the abort helper:

abort(404);

The abort helper will immediately raise an exception which will be rendered by the exception handler. Optionally, you may provide the response text:

abort(403, ‘Unauthorized action.’);

Question 14

How do you create a custom HTTP Error page?

Answer 14

Laravel makes it easy to display custom error pages for various HTTP status codes. For example, if you wish to customize the error page for 404 HTTP status codes, create a resources/views/errors/404.blade.php. This file will be served on all 404 errors generated by your application. The views within this directory should be named to match the HTTP status code they correspond to. The HttpException instance raised by the abort function will be passed to the view as an $exception variable.

Question 15

By default, Laravel is configured to create a log file for your application in the what directory?

Answer 15

storage/logs

Question 16

You may write information to the logs using what facade?

Answer 16

The Log facade:

User::findOrFail($id)]);
}
}

Question 17

The logger provides the eight logging levels defined in RFC 5424, which are?

Answer 17

emergency, alert, critical, error, warning, notice, info and debug:

Log::emergency($message);
Log::alert($message);
Log::critical($message);
Log::error($message);
Log::warning($message);
Log::notice($message);
Log::info($message);
Log::debug($message);

Question 18

How can logger methods utilize contextual data?

Answer 18

An array of contextual data may also be passed to the log methods. This contextual data will be formatted and displayed with the log message:

Log::info(‘User failed to login.’, [‘id’ => $user->id]);

Question 19

How do you access the underlying Monolog instance?

Answer 19

Monolog has a variety of additional handlers you may use for logging. If needed, you may access the underlying Monolog instance being used by Laravel:

$monolog = Log::getMonolog();