While offering some utility, the lifetime did not carry its weight, and
in practice offered no further ability to borrow. This greatly
simplifies request guard implementations.
This commit completely overhauls Rocket's configuration systems, basing
it on the new Figment library. It includes many breaking changes
pertaining to configuration. They are:
* "Environments" are replaced by "profiles".
* 'ROCKET_PROFILE' takes the place of 'ROCKET_ENV'.
* Profile names are now arbitrary, but 'debug' and 'release' are given
special treatment as default profiles for the debug and release
compilation profiles.
* A 'default' profile now sits along-side the meta 'global' profile.
* The concept of "extras" is no longer present; users can extract any
values they want from the configured 'Figment'.
* The 'Poolable' trait takes an '&Config'.
* The 'secrets' feature is disabled by default.
* It is a hard error if 'secrets' is enabled under the 'release'
profile and no 'secret_key' is configured.
* 'ConfigBuilder' no longer exists: all fields of 'Config' are public
with public constructors for each type.
* 'keep_alive' is disabled with '0', not 'false' or 'off'.
* Inlined error variants into the 'Error' structure.
* 'LoggingLevel' is now 'LogLevel'.
* Limits can now be specified in SI units: "1 MiB".
The summary of other changes are:
* The default config file can be configured with 'ROCKET_CONFIG'.
* HTTP/1 and HTTP/2 keep-alive configuration is restored.
* 'ctrlc' is now a recognized config option.
* 'serde' is now a core dependency.
* TLS misconfiguration errors are improved.
* Several example use '_' as the return type of '#[launch]' fns.
* 'AdHoc::config()' was added for simple config extraction.
* Added more documentation for using 'Limits'.
* Launch information is no longer treated specially.
* The configuration guide was rewritten.
Resolves#852.
Resolves#209.
Closes#1404.
Closes#652.
The connection guard type generated by `#[database]` no longer
implements `Deref` and `DerefMut`. Instead, it provides an `async fn
run()` that gives access to the underlying connection on a closure run
through `spawn_blocking()`.
Additionally moves most of the implementation of `#[database]` out
of generated code and into library code for better type-checking.
