SystemEnvironmentReader

The real environment: getenv() first, then $_ENV.

getenv() alone is not the whole environment a modern app runs in. A dotenv loader — vlucas/phpdotenv’s default createImmutable(), for one — populates $_ENV and $_SERVER and deliberately does not call putenv(), because putenv()/getenv() mutate process-global state that is not thread-safe. A reader that only asked getenv() would therefore answer “unset” for every variable such a bootstrap loaded, while answering correctly for the same variable set by a container runtime. Asking both makes the two indistinguishable to a caller, which is what they are to the deployment.

A real process variable wins over $_ENV: it is the one the platform set, and an immutable dotenv repository will not have overwritten it anyway. $_SERVER is deliberately not consulted even though dotenv writes there too — under CGI and FastCGI it also carries the request (HTTP_*, REQUEST_URI, QUERY_STRING), and configuration must not be able to reach that. Anything dotenv puts in $_SERVER it puts in $_ENV as well.

Only a string in $_ENV counts: the superglobal mirrors an environment whose values are strings, and a caller has an interface promising string|false to honour. This is what the container binds EnvironmentReaderInterface to by default; nothing here is mockable, which is the point — tests reach for a fake reader, putenv() or $_ENV instead of stubbing this class.

Synopsis

final class SystemEnvironmentReader implements EnvironmentReaderInterface

Implements	EnvironmentReaderInterface
Source	Support/Environment/SystemEnvironmentReader.php

Methods

Method	Description
[`get(string $name): string	false`](#get)

get()

public function get(string $name): string|false

The value of environment variable $name, or false when it is unset.

Parameter	Type	Description
$name	string

Returns string``|``false