[5.8] Handle DATABASE_URL env variable for database connection

[mathieutu]

Hi,
Many cloud providers use urls env var to configure the database connection (often DATABASE_URL), and many ORM (in many languages) handle them too.

The PR aims to handle those urls.

This is inspired by the Doctrine way to handle them.

This is just a draft, coming directly from my projects, feedback and comments are welcomed.

If someone in the Laravel core team confirms me that this is a wanted feature and that it will be merged, I will be glad to spend more time on it.

Roadmap:

• Add tests
• Edit database.php config file to use that class
• Add a redis part
• See something else?

Ideas for usage (to challenge, could be easier):

// database.php
[
	'default' => env('DATABASE_URL') ? 'url' : env('DB_CONNECTION', 'pgsql'),
	'connections' => [
		// ....
		'url' => UrlParser::parse(env('DATABASE_URL')),
	],
	// ....
]

Thanks,
Matt'

[taylorotwell]

Which cloud providers?

[m1guelpf]

Heroku does this, for example

[taylorotwell]

Please remove all the nullable type-hints. They are useless. Thanks.

[mathieutu]

@taylorotwell Sorry I don't understand what you mean: do you want that I remove all the type-hint or just the nullable part?
1 - ?string $alias => string $alias
2 - ?string $alias => $alias

Because in the first case, it will not work as I'm actually waiting for a nullable string, and doing checks on the null value.

Do you confirm that you're interested by adding and merging this feature, and so I can invest more time on it? If you need more examples of cloud providers, or ORM, I can look up and link them to you.

[taylorotwell]

So does Heroku not provide the traditional host name / port? You can only use this specifically formatted URL?

[taylorotwell]

I'm fine in general with supporting it if Heroku provides no other way to connect to databases.

[mathieutu]

This url is pretty standard, and heroku (for example) set this url in your project env variables, and rotate it automatically.

It's also easier to manage in other hosting ways, CI, and local projects because it's only one variable to set/copy instead of several.

I've seen Rails use that one too.

And icing on the cake, database software handle it to directly open your database on a click 😉!

[taylorotwell]

Is there somewhere the format of this URL is standardized / documented?

[mathieutu]

I didn't found anything really agnostically standardized, but each language/framework has its documentation:

• https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING
• https://dev.mysql.com/doc/connector-j/8.0/en/connector-j-reference-jdbc-url-format.html
• https://www.doctrine-project.org/projects/doctrine-dbal/en/2.9/reference/configuration.html#connecting-using-a-url
• https://eggerapps.at/postico/docs/v1.5.6/postico-url-scheme.html
• https://node-postgres.com/features/connecting#connection-uri
• https://guides.rubyonrails.org/configuring.html#configuring-a-database

At the end, it's the classic url format (same than for http and ftp protocoles or any software)

scheme://username:password@host:port/path?query

so in a database context:

driver://username:password@server:port/database?additional_parameters

Examples:
mysql://localhost:4486/foo?charset=UTF-8
pgsql://user:secret@localhost/mydb
sqlite:///somedb.sqlite

The behavior will be clearer when test will be added.

[taylorotwell]

Gotcha.

[taylorotwell]

Feel free to add tests.

[taylorotwell]

Closing pending inactivity but I do think this is kind of a nice idea if anyone else wants to pick it up.

[mathieutu]

Hey folks, I've made another PR : #28308!