Explain Symfony Bootstratpping Process (to be continued !!!)

Symfony Bootstratpping Process

1. load environment variables from .env files in _ENV and _SERVER super global among APP_ENV and APP_DEBUG
2. enable debug component if APP_DEBUG is true
3. instantiate kernel with APP_ENV and APP_DEBUG
4. create Request object from super globals
5. call handle method on kernel with Request object
    1. prepare registered bundles array
    2. initialize service container
        1. initiate ContainerBuilder object and add its definition with service_container id
        2. add some kernel parameters
        3. if kernel implement CompilerPassInterface, add it as compiler pass
        4. register bundle’s extensions (Extension’s load method called by MergeExtensionConfigurationPass and bundle’s configurations and temporary container injected in it and then merged with others, this compiler pass is always the first compiler pass). in this step we just add extension to an array
        5. build method on each bundle and kernel called. its a good place for adding compiler pass
        6. implicitly set compiler merge pass with extensions’s alias
        7. initiate config loader resolver
        8. set router with kernel::loadRoutes
        9. register kernel as synthetic and public service and add routing.route_loader tag (loadRoutes will call)
        10. if kernel implements EventSubscriberInterface add kernel.event_subscriber tag to it
        11. service definitions and configurations load in service container by convention with help of config loader resolver. service definitions are loaded in definitions parameter and configurations are loaded in extensionConfigs parameter
        12. service container compiled and pass throw the chain of compiler passes (all service container features implemented by one compiler pass)
        13. all configurations become parameter in service container with . notation prefix for bundle alias. this done by MergeExtensionConfigurationPass. SO THIS COMPILER PASS CALL EXTENSION’S LOAD METHOD WITH ARRAY OF CONFIGURATIONS AND FRESH INSTANCE OF SERVICE CONTAINER AND THEN MERGE IT WITH MAIN SERVICE CONTAINER
        14. in extension’s load method, extension can load and validate configurations and service definitions and then set definitions for services and set parameters in injected service container
        15. service container cached
    3. inject service container to each bundle via setContainer method and call its boot method
    4. call handle on HttpKernel
        1. push Request to stack
        2. ...
    1. create Response object
6. send Response to client
    1. send headers
    2. send content
7. terminate kernel