Restructure configuration (LukeMathWalker#199)

This PR restructures configuration in both the RealWorld example and the
starter template.
The goal is to separate the application config (which can and should be
injected) from the server config (which is only needed at startup). We
also provide an example of how to add additional app configuration.

Other misc changes:

- I removed the `Test` application profile, since it's not really a fit.
The tests change the configuration anyway and they can start from the
development one.
- I've added the telemetry setup to the tests in the starter project.

doc_examples/quickstart/02-register_new_route.snap

@@ -4,6 +4,7 @@ pub fn blueprint() -> Blueprint {
     let mut bp = Blueprint::new();
     ApiKit::new().register(&mut bp);
     telemetry::register(&mut bp);
+    ApplicationConfig::register(&mut bp);
 
     bp.route(GET, "/api/ping", f!(crate::routes::status::ping));
     bp.route(

doc_examples/quickstart/02.patch

@@ -1,10 +1,10 @@
 diff --git a/demo/src/blueprint.rs b/demo/src/blueprint.rs
-index 4a196d8..0a6857d 100644
+index f2b3732..a282fa0 100644
 --- a/demo/src/blueprint.rs
 +++ b/demo/src/blueprint.rs
-@@ -11,6 +11,11 @@ pub fn blueprint() -> Blueprint {
-     add_telemetry_middleware(&mut bp);
- 
+@@ -12,5 +12,10 @@ pub fn blueprint() -> Blueprint {
+     ApplicationConfig::register(&mut bp);
+
      bp.route(GET, "/api/ping", f!(crate::routes::status::ping));
 +    bp.route(
 +        GET,
@@ -13,7 +13,7 @@ index 4a196d8..0a6857d 100644
 +    );
      bp
  }
- 
+
 diff --git a/demo/src/routes/greet.rs b/demo/src/routes/greet.rs
 new file mode 100644
 index 0000000..38ec1e3

doc_examples/quickstart/04-register_common_invocation.snap

@@ -4,5 +4,6 @@ pub fn blueprint() -> Blueprint {
     let mut bp = Blueprint::new();
     ApiKit::new().register(&mut bp);
     // [...]
+    bp
 }
 ```

doc_examples/quickstart/05-bis.patch

@@ -1,9 +1,10 @@
 diff --git a/demo/src/blueprint.rs b/demo/src/blueprint.rs
+index a282fa0..2067e4a 100644
 --- a/demo/src/blueprint.rs
 +++ b/demo/src/blueprint.rs
-@@ -11,11 +11,7 @@ pub fn blueprint() -> Blueprint {
-     add_telemetry_middleware(&mut bp);
- 
+@@ -12,10 +12,6 @@ pub fn blueprint() -> Blueprint {
+     ApplicationConfig::register(&mut bp);
+
      bp.route(GET, "/api/ping", f!(crate::routes::status::ping));
 -    bp.route(
 -        GET,
@@ -13,7 +14,7 @@ diff --git a/demo/src/blueprint.rs b/demo/src/blueprint.rs
 +    bp.route(GET, "/api/greet/:name", f!(crate::routes::greet::greet));
      bp
  }
- 
+
 diff --git a/demo/src/routes/greet.rs b/demo/src/routes/greet.rs
 --- a/demo/src/routes/greet.rs
 +++ b/demo/src/routes/greet.rs

doc_examples/quickstart/05-error.snap

@@ -3,12 +3,12 @@
   │ instance of `demo::user_agent::UserAgent` as input, but I can't find a constructor for that
   │ type.
   │
-  [31m│[0m     ╭─[[36;1;4mdemo/src/blueprint.rs[0m:13:1]
-  [31m│[0m  [2m13[0m │     bp.route(GET, "/api/ping", f!(crate::routes::status::ping));
-  [31m│[0m  [2m14[0m │     bp.route(GET, "/api/greet/:name", f!(crate::routes::greet::greet));
+  [31m│[0m     ╭─[[36;1;4mdemo/src/blueprint.rs[0m:14:1]
+  [31m│[0m  [2m14[0m │     bp.route(GET, "/api/ping", f!(crate::routes::status::ping));
+  [31m│[0m  [2m15[0m │     bp.route(GET, "/api/greet/:name", f!(crate::routes::greet::greet));
   │     ·                                       ───────────────┬───────────────
   │     ·            The request handler was registered here ──╯
-  [31m│[0m  [2m15[0m │     bp
+  [31m│[0m  [2m16[0m │     bp
   │     ╰────
   │     ╭─[demo/src/routes/greet.rs:10:1]
   │  10 │ 

doc_examples/quickstart/06.patch

@@ -2,14 +2,14 @@ diff --git a/demo/src/blueprint.rs b/demo/src/blueprint.rs
 --- a/demo/src/blueprint.rs
 +++ b/demo/src/blueprint.rs
 @@ -1,4 +1,5 @@
- use crate::telemetry;
+ use crate::{configuration::ApplicationConfig, telemetry};
 +use pavex::blueprint::constructor::Lifecycle;
  use pavex::blueprint::{router::GET, Blueprint};
  use pavex::f;
  use pavex::kit::ApiKit;
-@@ -10,6 +11,11 @@ pub fn blueprint() -> Blueprint {
-     ApiKit::new().register(&mut bp);
+@@ -11,6 +12,11 @@ pub fn blueprint() -> Blueprint {
      telemetry::register(&mut bp);
+     ApplicationConfig::register(&mut bp);
 
 +    bp.constructor(
 +        f!(crate::user_agent::UserAgent::extract),

doc_examples/quickstart/07-error.snap

@@ -3,12 +3,12 @@
   │ handler for it. If I don't have an error handler, I don't know what to do with the error when
   │ the constructor fails!
   │
-  [31m│[0m     ╭─[[36;1;4mdemo/src/blueprint.rs[0m:14:1]
-  [31m│[0m  [2m14[0m │     bp.constructor(
-  [31m│[0m  [2m15[0m │         f!(crate::user_agent::UserAgent::extract),
+  [31m│[0m     ╭─[[36;1;4mdemo/src/blueprint.rs[0m:15:1]
+  [31m│[0m  [2m15[0m │     bp.constructor(
+  [31m│[0m  [2m16[0m │         f!(crate::user_agent::UserAgent::extract),
   │     ·         ────────────────────┬────────────────────
   │     ·                             ╰── The fallible constructor was registered here
-  [31m│[0m  [2m16[0m │         Lifecycle::RequestScoped,
+  [31m│[0m  [2m17[0m │         Lifecycle::RequestScoped,
   │     ╰────
   │   help: Add an error handler via `.error_handler`
 

doc_examples/quickstart/demo-blueprint_definition.snap

@@ -4,6 +4,7 @@ pub fn blueprint() -> Blueprint {
     let mut bp = Blueprint::new();
     ApiKit::new().register(&mut bp);
     telemetry::register(&mut bp);
+    ApplicationConfig::register(&mut bp);
 
     bp.route(GET, "/api/ping", f!(crate::routes::status::ping));
     bp

doc_examples/quickstart/demo-bp_server_binary.snap

@@ -1,11 +1,12 @@
 ```rust title="demo_server/src/bin/api.rs"
 use anyhow::Context;
 use demo_server::{
-    configuration::load_configuration,
+    configuration::Config,
     telemetry::{get_subscriber, init_telemetry},
 };
 use demo_server_sdk::{build_application_state, run};
 use pavex::server::Server;
+use pavex_tracing::fields::{error_details, error_message, ERROR_DETAILS, ERROR_MESSAGE};
 
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
@@ -16,9 +17,10 @@ async fn main() -> anyhow::Result<()> {
     // in order to have a single choke point where we make sure to log fatal errors
     // that will cause the application to exit.
     if let Err(e) = _main().await {
-        tracing::error!(
-            error.msg = %e,
-            error.error_chain = ?e,
+        tracing::event!(
+            tracing::Level::ERROR,
+            { ERROR_MESSAGE } = error_message(&e),
+            { ERROR_DETAILS } = error_details(&e),
             "The application is exiting due to an error"
         )
     }
@@ -30,7 +32,7 @@ async fn _main() -> anyhow::Result<()> {
     // Load environment variables from a .env file, if it exists.
     let _ = dotenvy::dotenv();
 
-    let config = load_configuration(None)?;
+    let config = Config::load(None)?;
     let application_state = build_application_state().await;
 
     let tcp_listener = config

doc_examples/quickstart/demo-route_registration.snap

@@ -4,6 +4,7 @@ pub fn blueprint() -> Blueprint {
     let mut bp = Blueprint::new();
     ApiKit::new().register(&mut bp);
     telemetry::register(&mut bp);
+    ApplicationConfig::register(&mut bp);
 
     bp.route(GET, "/api/ping", f!(crate::routes::status::ping));
     bp

doc_examples/quickstart/tutorial.yml

@@ -96,7 +96,7 @@ steps:
         hl_lines: [ 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 ]
       - name: "register"
         source_path: "demo/src/blueprint.rs"
-        ranges: [ "8..9", "13..17", "21..22" ]
+        ranges: [ "8..9", "14..18", "22..23" ]
         hl_lines: [ 10, 11, 12, 13 ]
     commands:
       - command: "cargo px c"
@@ -117,7 +117,7 @@ steps:
         ranges: [ "21..25" ]
       - name: "register"
         source_path: "demo/src/blueprint.rs"
-        ranges: [ "8..9", "13..18", "22..23" ]
+        ranges: [ "8..9", "14..19", "23..24" ]
         hl_lines: [ 8 ]
     commands:
       - command: "cargo px c"

docs/guide/project_structure/index.md

@@ -37,16 +37,17 @@ Using the `demo` project as an example, the relationship between the project cra
 graph 
   d[demo] -->|contains| bp[Blueprint];
   bp -->|is used to generate| dss[demo_server_sdk];
-  dss -->|is invoked by| ds[demo_server];
-  dss -->|is invoked by| dst[API tests in demo_server];
+  dss -->|is used by| ds[demo_server];
+  dss -->|is used by| dst[API tests in demo_server];
 ```
 
 If you want to know more, read on!
 
 ## Blueprint
 
 Every Pavex project has, at its core, a [`Blueprint`][Blueprint].  
-It's the type you use to declare the structure of your API: [routes], middlewares, [constructors], error handlers, etc.
+It's the type you use to declare the structure of your API:
+[routes], [middlewares], [constructors], [error handlers], [error observers], etc.
 
 --8<-- "doc_examples/quickstart/demo-blueprint_definition.snap"
 
@@ -183,4 +184,7 @@ The `demo` project includes an example of such a test which you can use as a ref
 
 [routes]: ../routing/index.md
 [constructors]: ../dependency_injection/index.md
+[middlewares]: ../middleware/index.md
+[error handlers]: ../errors/error_handlers.md
+[error observers]: ../errors/error_observers.md
 [cargo-px]: https://github.com/LukeMathWalker/cargo-px

examples/realworld/api_server/Cargo.toml

@@ -22,6 +22,7 @@ serde = { version = "1", features = ["derive"]}
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", default-features = false, features = ["env-filter", "smallvec", "std", "registry", "tracing-log"] }
 tracing-bunyan-formatter = "0.3"
+pavex_tracing = { path = "../../../libs/pavex_tracing" }
 
 [dev-dependencies]
 reqwest = { version = "0.11", features = ["json"] }

examples/realworld/api_server/configuration/prod.yml

@@ -1,4 +1,5 @@
 server:
   ip: "0.0.0.0"
-database:
-  require_ssl: true
+app:
+  database:
+    require_ssl: true

examples/realworld/api_server/configuration/test.yml

@@ -6,16 +6,17 @@ server:
   ip: "127.0.0.1"
   # The OS will assign a random port to the test server.
   port: 0
-auth:
-  # Placeholder values, they'll be replaced with real values
-  # generated on the fly before launching the test server.
-  eddsa_private_key_pem: "secret"
-  eddsa_public_key_pem: "secret"
-# Same parameters used in /scripts/init_db.sh
-database:
-  host: "127.0.0.1"
-  port: 5432
-  username: "postgres"
-  password: "password"
-  database_name: "conduit"
-  require_ssl: false
+app:
+  auth:
+    # Placeholder values, they'll be replaced with real values
+    # generated on the fly before launching the test server.
+    eddsa_private_key_pem: "secret"
+    eddsa_public_key_pem: "secret"
+  # Same parameters used in /scripts/init_db.sh
+  database:
+    host: "127.0.0.1"
+    port: 5432
+    username: "postgres"
+    password: "password"
+    database_name: "conduit"
+    require_ssl: false

examples/realworld/api_server/src/bin/api.rs

@@ -1,23 +1,23 @@
 use anyhow::Context;
-use api_server::{
-    configuration::load_configuration,
-    telemetry::{get_subscriber, init_telemetry},
-};
+use api_server::configuration::Config;
+use api_server::telemetry::{get_subscriber, init_telemetry};
 use api_server_sdk::{build_application_state, run};
 use pavex::server::Server;
+use pavex_tracing::fields::{error_details, error_message, ERROR_DETAILS, ERROR_MESSAGE};
 
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     let subscriber = get_subscriber("realworld".into(), "info".into(), std::io::stdout);
     init_telemetry(subscriber)?;
 
     // We isolate all the server setup and launch logic in a separate function
-    // in order to have a single choke point where we make sure to log fatal errors
+    //  to have a single choke point where we make sure to log fatal errors
     // that will cause the application to exit.
     if let Err(e) = _main().await {
-        tracing::error!(
-            error.msg = %e,
-            error.error_chain = ?e,
+        tracing::event!(
+            tracing::Level::ERROR,
+            { ERROR_MESSAGE } = error_message(&e),
+            { ERROR_DETAILS } = error_details(&e),
             "The application is exiting due to an error"
         )
     }
@@ -26,8 +26,8 @@ async fn main() -> anyhow::Result<()> {
 }
 
 async fn _main() -> anyhow::Result<()> {
-    let config = load_configuration(None)?;
-    let application_state = build_application_state(&config.auth, &config.database)
+    let config = Config::load(None)?;
+    let application_state = build_application_state(&config.app)
         .await
         .context("Failed to build the application state")?;