如何掌握和创建新的运行环境

Different Environments, different Configuration Files¶

A typical Symfony application begins with three environments: dev, prod, and test. As discussed, each “environment” simply represents a way to execute the same codebase with different configuration. It should be no surprise then that each environment loads its own individual configuration file. If you’re using the YAML configuration format, the following files are used:

• for the dev environment: app/config/config_dev.yml
• for the prod environment: app/config/config_prod.yml
• for the test environment: app/config/config_test.yml

This works via a simple standard that’s used by default inside the AppKernel class:

// app/AppKernel.php

// ...

class AppKernel extends Kernel
{
    // ...

    public function registerContainerConfiguration(LoaderInterface $loader)
    {
        $loader->load(__DIR__.'/config/config_'.$this->getEnvironment().'.yml');
    }
}

As you can see, when Symfony is loaded, it uses the given environment to determine which configuration file to load. This accomplishes the goal of multiple environments in an elegant, powerful and transparent way.

Of course, in reality, each environment differs only somewhat from others. Generally, all environments will share a large base of common configuration. Opening the “dev” configuration file, you can see how this is accomplished easily and transparently:

To share common configuration, each environment’s configuration file simply first imports from a central configuration file (config.yml). The remainder of the file can then deviate from the default configuration by overriding individual parameters. For example, by default, the web_profiler toolbar is disabled. However, in the dev environment, the toolbar is activated by modifying the default value in the dev configuration file:

Executing an Application in different Environments¶

To execute the application in each environment, load up the application using either the app.php (for the prod environment) or the app_dev.php (for the dev environment) front controller:

http://localhost/app.php      -> *prod* environment
http://localhost/app_dev.php  -> *dev* environment

If you open up one of these files, you’ll quickly see that the environment used by each is explicitly set:

// web/app.php
// ...

$kernel = new AppKernel('prod', false);

// ...

As you can see, the prod key specifies that this application will run in the prod environment. A Symfony application can be executed in any environment by using this code and changing the environment string.

# 'dev' environment and debug enabled
$ php app/console command_name

# 'prod' environment (debug is always disabled for 'prod')
$ php app/console command_name --env=prod

# 'test' environment and debug disabled
$ php app/console command_name --env=test --no-debug

Creating a new Environment¶

By default, a Symfony application has three environments that handle most cases. Of course, since an environment is nothing more than a string that corresponds to a set of configuration, creating a new environment is quite easy.

Suppose, for example, that before deployment, you need to benchmark your application. One way to benchmark the application is to use near-production settings, but with Symfony’s web_profiler enabled. This allows Symfony to record information about your application while benchmarking.

The best way to accomplish this is via a new environment called, for example, benchmark. Start by creating a new configuration file:

And with this simple addition, the application now supports a new environment called benchmark.

This new configuration file imports the configuration from the prod environment and modifies it. This guarantees that the new environment is identical to the prod environment, except for any changes explicitly made here.

Because you’ll want this environment to be accessible via a browser, you should also create a front controller for it. Copy the web/app.php file to web/app_benchmark.php and edit the environment to be benchmark:

// web/app_benchmark.php
// ...

// change just this line
$kernel = new AppKernel('benchmark', false);

// ...

The new environment is now accessible via:

http://localhost/app_benchmark.php

if (!in_array(@$_SERVER['REMOTE_ADDR'], array('127.0.0.1', '::1'))) {
    die('You are not allowed to access this file. Check '.basename(__FILE__).' for more information.');
}

Environments and the Cache Directory¶

Symfony takes advantage of caching in many ways: the application configuration, routing configuration, Twig templates and more are cached to PHP objects stored in files on the filesystem.

By default, these cached files are largely stored in the app/cache directory. However, each environment caches its own set of files:

<your-project>/
├─ app/
│  ├─ cache/
│  │  ├─ dev/   # cache directory for the *dev* environment
│  │  └─ prod/  # cache directory for the *prod* environment
│  ├─ ...

Sometimes, when debugging, it may be helpful to inspect a cached file to understand how something is working. When doing so, remember to look in the directory of the environment you’re using (most commonly dev while developing and debugging). While it can vary, the app/cache/dev directory includes the following:

• appDevDebugProjectContainer.php - the cached “service container” that represents the cached application configuration;
• appDevUrlGenerator.php - the PHP class generated from the routing configuration and used when generating URLs;
• appDevUrlMatcher.php - the PHP class used for route matching - look here to see the compiled regular expression logic used to match incoming URLs to different routes;
• twig/ - this directory contains all the cached Twig templates.

Going further¶

Read the article on 如何将Service Container的参数暴露到外部.