Generate embed code instead of using interpolation (#828)

Because the output path of the embedded files changes per machine, the
interpolate-folder-path feature of rust-embed was used to set the
correct embed path. This feature however creates a rather large
dependency tree (shell_expand -> dirs -> dirs-sys -> option-ext)

By generating a small file with the correct folder already filled in,
then including it in lib.rs we can remove this feature and reduce the
amount of dependencies that are used.

Implementation was inspired by how the "built" crate recommends people
to use it.

utoipa-swagger-ui/Cargo.toml

@@ -15,7 +15,7 @@ debug = []
 debug-embed = ["rust-embed/debug-embed"]
 
 [dependencies]
-rust-embed = { version = "8", features = ["interpolate-folder-path"] }
+rust-embed = { version = "8" }
 mime_guess = { version = "2.0" }
 actix-web = { version = "4", optional = true, default-features = false }
 rocket = { version = "0.5.0-rc.3", features = ["json"], optional = true }

utoipa-swagger-ui/build.rs

@@ -13,10 +13,8 @@ const SWAGGER_UI_DIST_ZIP: &str = "swagger-ui-5.3.1";
 
 fn main() {
     println!("cargo:rerun-if-changed=res/{SWAGGER_UI_DIST_ZIP}.zip");
-    println!("cargo:rustc-env=UTOIPA_SWAGGER_UI_VERSION={SWAGGER_UI_DIST_ZIP}");
 
     let target_dir = env::var("OUT_DIR").unwrap();
-    println!("cargo:rustc-env=UTOIPA_SWAGGER_DIR={}", &target_dir);
 
     let swagger_ui_zip = File::open(
         ["res", &format!("{SWAGGER_UI_DIST_ZIP}.zip")]
@@ -29,6 +27,8 @@ fn main() {
     extract_within_path(&mut zip, [SWAGGER_UI_DIST_ZIP, "dist"], &target_dir).unwrap();
 
     replace_default_url_with_config(&target_dir);
+
+    write_embed_code(&target_dir, &SWAGGER_UI_DIST_ZIP);
 }
 
 fn extract_within_path<const N: usize>(
@@ -96,3 +96,17 @@ fn replace_default_url_with_config(target_dir: &str) {
 
     fs::write(&path, replaced_swagger_initializer.as_ref()).unwrap();
 }
+
+fn write_embed_code(target_dir: &str, swagger_version: &str) {
+    let contents = format!(
+        r#"
+// This file is auto-generated during compilation, do not modify
+#[derive(RustEmbed)]
+#[folder = "{}/{}/dist/"]
+struct SwaggerUiDist;
+"#,
+        target_dir, swagger_version
+    );
+    let path = [target_dir, "embed.rs"].iter().collect::<PathBuf>();
+    fs::write(&path, &contents).unwrap();
+}

utoipa-swagger-ui/src/lib.rs

@@ -120,9 +120,7 @@ use serde::Serialize;
 #[cfg(any(feature = "actix-web", feature = "rocket", feature = "axum"))]
 use utoipa::openapi::OpenApi;
 
-#[derive(RustEmbed)]
-#[folder = "$UTOIPA_SWAGGER_DIR/$UTOIPA_SWAGGER_UI_VERSION/dist/"]
-struct SwaggerUiDist;
+include!(concat!(env!("OUT_DIR"), "/embed.rs"));
 
 /// Entry point for serving Swagger UI and api docs in application. It provides
 /// builder style chainable configuration methods for configuring api doc urls.