Launch fairings are now fallible and take the place of attach fairings,
but they are only run, as the name implies, at launch time.
This is is a fundamental shift from eager execution of set-up routines,
including the now defunct attach fairings, to lazy execution,
precipitated by the transition to `async`. The previous functionality,
while simple, caused grave issues:
1. A instance of 'Rocket' with async attach fairings requires an async
runtime to be constructed.
2. The instance is accessible in non-async contexts.
3. The async attach fairings have no runtime in which to be run.
Here's an example:
```rust
let rocket = rocket::ignite()
.attach(AttachFairing::from(|rocket| async {
Ok(rocket.manage(load_from_network::<T>().await))
}));
let state = rocket.state::<T>();
```
This had no real meaning previously yet was accepted by running the
attach fairing future in an isolated runtime. In isolation, this causes
no issue, but when attach fairing futures share reactor state with other
futures in Rocket, panics ensue.
The new Rocket application lifecycle is this:
* Build - A Rocket instance is constructed. No fairings are run.
* Ignition - All launch fairings are run.
* Liftoff - If all launch fairings succeeded, the server is started.
New 'liftoff' fairings are run in this third phase.
This commit reverts most of dea940c7 and d89c7024. The "fix" is to run
attach fairings on a new thread. If a runtime is already running, it is
used. Otherwise, the future is executed in a single-threaded executor.
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.
observed.
This is a prerequisite for async on_attach fairings. 'Rocket' is now a
builder wrapper around the 'Manifest' type, with operations being
applied when needed by 'launch()', 'Client::new()', or 'inspect()'.
'inspect()' returns an '&Manifest', which now provides the methods that
could be called on an '&Rocket'.
Sergio Benitez
Jeb Rosen
Leonora Tindall
Eric Dattore
Eric Dattore