• Hide environment variables on the debugging page
• Access configuration values
• Configuration Cache
• Maintenance Mode

Configuration

• Introduction
• Environment configuration
  • Environment variable type
  • Retrieve environment configuration
  • Determine the current environment
  • ##Hide environment variables on the debugging page
• Access configuration values
• Configuration cache
• Maintenance mode

config directory. Each option is described, and you can review these files at any time to familiarize yourself with what configuration options are available to you.

.env.example file. If Laravel is installed through Composer, this file will be automatically renamed .env. Otherwise, you need to manually change the file name.

.env file should not be committed to your application's source control system, as each developer/server using your application may need to have a different environment configuration. Additionally, in the event that an intruder gains access to your source control repository, this becomes a security risk because any sensitive credentials are exposed.

.env.example file in your application. Because by placing placeholder values ​​in the sample configuration file, other developers on the team can clearly see which environment variables are required to run the application. You can also create a .env.testing file that will overwrite .env when running PHPUnit tests or executing Artisan commands with the --env=testing option. Value in the file.

{tip}

.env All variables in the file can be overridden by external environment variables (such as server-level or system-level environment variables).

.env All variables in the file are parsed as strings, Therefore some reserved values ​​were created to allow you to return more types of variables from the env() function:

If you need to define an environment variable with a value that contains spaces, you can do so by enclosing the value in double quotes.

APP_NAME="我的 应用"

Retrieve environment configuration

When the application receives a request, all the items listed in the .env file The variable will be loaded into PHP's super global variable $ _ENV. You can retrieve the values ​​of these variables using the env function. In fact, if you look at Laravel's configuration file, you'll notice that several options already use this function:

'debug' => env('APP_DEBUG', false),

The second value passed to the env function is "default" value". If no environment variable exists for the given key, this value will be used.

Determine the current environment

The current environment of the application is passed APP_ENV in the .env file Variable determined. You can access this value through the environment method in the App facade:

$environment = App::environment();

You can also pass parameters to the environment method to check Whether the current environment configuration matches the given value. This method will return true if it matches the given value:

if (App::environment('local')) {  
  // 当前环境是 local
  }
if (App::environment(['local', 'staging'])) {  
  // 当前的环境是 local 或 staging...
  }

{tip} The current environment of the application can be detected by the server-level APP_ENVEnvironment variable coverage. This is useful when configuring different environments for the same application, so that you can set a given environment to match a given host in your server configuration.

Hide environment variables in the debug page

When an exception is not caught and APP_DEBUG the environment variable is true, the debug page will display all environment variables and content. In some cases you may want to hide certain variables. You can do this by setting the debug_blacklist option in the config/app.php configuration file.

Some variables are available in environment variables, server or request data. Therefore, you may need to add the $_ENV and $_SERVER variables to the blacklist:

return [  
  // ...  
  'debug_blacklist' => [ 
     '_ENV' => [ 
           'APP_KEY',  
           'DB_PASSWORD', 
        ],   
     '_SERVER' => [  
           'APP_KEY', 
            'DB_PASSWORD',   
          ],  
      '_POST' => [        
          'password',  
          ], 
       ],
   ];

Accessing configuration values

You can easily access configuration values ​​from anywhere in your application using the global config function. Configuration values ​​can be accessed using "dot" syntax, which contains the name of the file and option to be accessed. You can also specify a default value, which is returned if the configuration option does not exist:

$value = config('app.timezone');

To set the configuration value at runtime, pass an array to the config function

config(['app.timezone' => 'America/Chicago']);

Configuration Cache

To improve the speed of your application, you should cache all configuration files using the Artisan command config:cache into a single file. This will combine all the configuration options in your application into a single file, which will then be quickly loaded by the framework.

Generally speaking, you should run the php artisan config:cache command as part of your regular production environment deployment. This command should not be run in a local development environment because configuration options often need to be changed during application development.

{note} If you execute the config:cache command during deployment, you should ensure that you only call the env function from within the configuration file. Once the configuration is cached, the .env file will no longer be loaded and all calls to the env function will return null.

Maintenance Mode

When the application is in maintenance mode, all requests to the application are displayed as a custom view . This makes it easy to "shut down" your application when updating or performing maintenance. Maintenance mode checks are included in the application's default middleware stack. If the application is in maintenance mode, a MaintenanceModeException exception with status code 503 will be thrown.

To enable maintenance mode, simply execute Artisan's down command below:

php artisan down

You can also provide to the down command message and retry options. The value of the message option can be used to display or record a custom message, and the retry value can be used to set the value of Retry-After in the HTTP request header:

php artisan down --message="Upgrading Database" --retry=60

Even in maintenance mode, you can allow specific IP addresses or networks to access the application using the command allow option:

php artisan down --allow=127.0.0.1 --allow=192.168.0.0/16

To turn off maintenance mode, use up Command:

php artisan up

{tip} You can customize the default maintenance mode template by modifying the resources/views/errors/503.blade.php template file.

Maintenance Mode & Queue

When the application is in maintenance mode, queue tasks are not processed. These tasks will continue to be processed after the application exits maintenance mode.

Alternatives to Maintenance Mode

Maintenance mode can cause your application to have seconds of downtime (non-responsiveness), so you may consider using an alternative like Envoyer to get zero done with Laravel Downtime deployment.