feat: Configure Rust functions (#430)

* Add ability to add all custom function configuration in a separate module.

Co-authored-by: Dejan Bosanac <dejan@sensatic.net>
Co-authored-by: Jim Crossley <jcrossley3@gmail.com>

Co-authored-by: Jim Crossley <jcrossley3@gmail.com>

docs/guides/rust.md

@@ -17,20 +17,21 @@ fn
 ├── func.yaml
 ├── README.md
 └── src
+    ├── config.rs
     ├── handler.rs
     └── main.rs
 
 ```
 
 This is a full-featured, self-contained Rust application that uses the
-[actix](https://actix.rs/) web framework to listen for HTTP requests on port 8080. 
+[actix](https://actix.rs/) web framework to listen for HTTP requests on port 8080.
 
 See the generated [README.md](../../templates/rust/http/README.md) for
 details on building, testing, and deploying the app.
 
 You may have noticed the `func.yaml` file. This is a configuration
 file used by `func` to deploy your project as a service in your
-kubernetes cluster. 
+kubernetes cluster.
 
 For an event-triggered function, pass the `-t events` option to
 generate an app capable of responding to

templates/rust/events/README.md

@@ -5,7 +5,8 @@ Welcome to your new Rust function project! The boilerplate
 [`src/main.rs`](./src/main.rs). It's configured to invoke the `handle`
 function in [`src/handler.rs`](./src/handler.rs) in response to a POST
 request containing a valid `CloudEvent`. You should put your desired
-behavior inside that `handle` function.
+behavior inside that `handle` function. In case you need to configure
+some resources for your function, you can do that in the [`configure` function](./src/config.rs).
 
 The app will expose three endpoints:
 

templates/rust/events/src/config.rs

@@ -0,0 +1,26 @@
+use actix_web::web;
+
+/// Run custom configuration as part of the application building
+/// process.
+///
+/// This function should contain all custom configuration for your function application.
+///
+/// ```rust
+/// fn configure(cfg: &mut web::ServiceConfig) {
+///     let db_driver = my_db();
+///     cfg.data(db_driver.clone());
+/// }
+/// ```
+///
+/// Then you can use configured resources in your function.
+///
+/// ```rust
+/// pub async fn handle(
+///     event: Event,
+///     driver: web::Data<DbDriver>,
+/// ) -> Result<Event, actix_web::Error> {
+///     Ok(Event::default())
+/// }
+pub fn configure(_cfg: &mut web::ServiceConfig) {
+    log::info!("Configuring service");
+}

templates/rust/events/src/main.rs

@@ -1,6 +1,7 @@
 use actix_web::{web, App, HttpResponse, HttpServer};
 use env_logger as elog;
 
+mod config;
 mod handler;
 
 #[actix_web::main]
@@ -16,6 +17,7 @@ async fn main() -> std::io::Result<()> {
     HttpServer::new(|| {
         App::new()
             .wrap(actix_web::middleware::Logger::default())
+            .configure(config::configure)
             .route("/", web::post().to(handler::handle))
             .route(
                 "/health/{_:(readiness|liveness)}",

templates/rust/http/README.md

@@ -5,7 +5,8 @@ Welcome to your new Rust function project! The boilerplate
 [`src/main.rs`](./src/main.rs). It's configured to invoke the `index`
 function in [`src/handler.rs`](./src/handler.rs) in response to both
 GET and POST requests. You should put your desired behavior inside
-that `index` function.
+that `index` function. In case you need to configure
+some resources for your function, you can do that in the [`configure` function](./src/config.rs).
 
 The app will expose three endpoints:
 

templates/rust/http/src/config.rs

@@ -0,0 +1,26 @@
+use actix_web::web;
+
+/// Run custom configuration as part of the application building
+/// process.
+///
+/// This function should contain all custom configuration for your function application.
+///
+/// ```rust
+/// fn configure(cfg: &mut web::ServiceConfig) {
+///     let db_driver = my_db();
+///     cfg.data(db_driver.clone());
+/// }
+/// ```
+///
+/// Then you can use configured resources in your function.
+///
+/// ```rust
+/// pub async fn index(
+///     req: HttpRequest,
+///     driver: web::Data<DbDriver>,
+/// ) -> HttpResponse {
+///     HttpResponse::NoContent()
+/// }
+pub fn configure(_cfg: &mut web::ServiceConfig) {
+    log::info!("Configuring service");
+}

templates/rust/http/src/main.rs

@@ -1,6 +1,7 @@
 use actix_web::{web, App, HttpResponse, HttpServer};
 use env_logger as elog;
 
+mod config;
 mod handler;
 
 #[actix_web::main]
@@ -16,6 +17,7 @@ async fn main() -> std::io::Result<()> {
     HttpServer::new(|| {
         App::new()
             .wrap(actix_web::middleware::Logger::default())
+            .configure(config::configure)
             .route("/", web::get().to(handler::index))
             .route("/", web::post().to(handler::index))
             .route(