config-loader

Provides a object-oriented public interface to reading configuration files, and an object to Dependency Inject around your application to retrieve configuration values when you need them.

Currently only Yaml is included, and uses Symfony\Yaml.

The service provides the following:

• Required Keys. An exception will be thrown if the configuration does not contain all the required keys.
• Environment Configuration. The environment can either be parsed from a global.yml file under the environment key, or set at runtime via a simple setter. Other environments in the required_environments key have their configuration file ignored.

Installation

Installation is via Composer. Add the following to your composer.json file:

"require": {
    "j7mbo/config-loader": "dev-master" 
}

Usage

• Create the YamlConfigLoader object in your bootstrap.
• Set up your configuration files and choose to either use a global.yml file with the environment and required_environments keys, or set these at runtime using setters.
• Set any required keys that your application must have, using a setter.
• Run the YamlConfigLoader::load() method in a try/catch and be ready for any exceptions like InvalidDirectoryException. Handle these accordingly, usually by logging the exception (for example, via Monolog\Logger) and providing a friendly message to the user.
• If all goes well, you then pass the YamlConfigLoader through your application, and call YamlConfigLoader::getConfiguration() to retrieve the configuration array.

Example

First, create a configuration directory containing your YAML files. These could be dev.yml, sandbox.yml, staging.yml and live.yml.

In the following code, we'll need to set the required (possible) environments to the same name as the environmental files above, and also our actual environment as the environment to be used.

// bootstrap.php
require_once __DIR__ . "/vendor/autoload.php"; // You'll need the composer autoloader included

$parser = new Symfony\Component\Yaml\Yaml; // The Symfony YAML parser
$iteratorFactory = new ConfigLoader\FileSystemIteratorFactory; // Factory for a directory iterator
$configLoader = new ConfigLoader\YamlConfigLoader($parser, $iteratorFactory);
$configLoader->setEnvironment("dev");
$configLoader->setPossibleEnvironments(["dev", "sandbox", "staging", "live"]);

// sandbox.yml, staging.yml and live.yml will be ignored, whilst dev.yml will be parsed
// Usually, these files have identical keys, but different values (db settings etc)

try
{
    $configLoader->setDirectory( __DIR__ . "/config"); // Set the directory for our config files
    $configLoader->load(); // Parse the data into the class configuration member
    var_dump($configLoader->getConfiguration()); // This is the method you can use when you pass this configuration object around your application.
}
catch (ConfigLoader\Exception\InvalidDirectoryException $e)
{
    echo "You have a permissions exception, or the directory doesn't exist";
    // The config directory doesn't exist or isn't readable
    // Log the error message
    // Show a nice message to the user
}

More Info

Constructor Directory Parameter

You can pass the directory as the third parameter of the YamlConfigLoader::__construct() method. However, you will need to catch an InvalidDirectoryExecption here also, as it is the directory setter that performs the validation and throws the exception, and the constructor uses this setter instead of setting the member variable directly.

Non-runtime environment settings

If you don't want to have to change your code every time you change your environment, you don't have to use the YamlConfigLoader::setEnvironment() and YamlConfigLoader::setPossibleEnvironments() methods. Instead, create a global.yml file with the keys environment (containing a single value string) and required_environments (containing subkeys of multiple values).

If you omit the runtime method calls, the following exceptions will be thrown if the environment and required_environments keys are not found, or if the global.yml file is not found:

• ConfigLoader\Exception\GlobalConfigFileNotFoundException
• ConfigLoader\Exception\NonExistentEnvironmentKeyException
• ConfigLoader\Exception\NonExistentRequiredConfigKeyException

Ensure a valid configuration set

You can also ensure that a configuration is always valid by using YamlConfigLoader::setRequiredKeys(), with an array as it's only parameter. If any of these keys are not found after performing the load() call, then the NonExistentRequiredConfigKeyException is thrown.

Get a specific configuration set by key

You don't have to request the whole configuration set. Sometimes it's clearer to request configuration details by a specific key. The getter for the configuration allows a parameter to do just this:

`YamlConfigLoader::getConfiguration($key = "database");` 

This returns either an array with the key "database" from your configuration, or an empty array if they key does not exist. No exceptions are thrown here.

getConfiguration() -> getConfig()

You can use YamlConfigLoader::getConfig() as a shortcut to YamlConfigLoader::getConfiguration().

Extension

You can add your own config-loader classes by implementing ConfigurationInterface and following along the lines of the YamlConfigLoader. Make sure to add a test for this in the test/ directory.

Additional Notes

This class-set is almost like a service locator for your configuration, but not quite. It's just an object oriented way of passing around a configuration array of keys and values. If you have a large application then this probably isn't the best approach, but for small applications it isn't an issue calling $this->config->getConfiguration("database");.

Depending on how you have set up your code, you could dependency inject specific configuration classes into your services - but that is not the aim of this class.