Simplify OG_IMAGE_BASE_URL usage

If `OG_IMAGE_BASE_URL` is not set we can fall back to the default image instead of using `.unwrap()` and assuming that the option is always set.

Author: Turbo87

src/config/server.rs

@@ -12,7 +12,7 @@ use crate::config::cdn_log_storage::CdnLogStorageConfig;
 use crate::config::CdnLogQueueConfig;
 use crate::middleware::cargo_compat::StatusCodeConfig;
 use crate::storage::StorageConfig;
-use crates_io_env_vars::{list, list_parsed, required_var, required_var_parsed, var, var_parsed};
+use crates_io_env_vars::{list, list_parsed, required_var, var, var_parsed};
 use http::HeaderValue;
 use std::collections::{HashMap, HashSet};
 use std::convert::Infallible;
@@ -74,8 +74,6 @@ pub struct Server {
 
     /// Should the server serve the frontend `index.html` for all
     /// non-API requests?
-    /// Setting this parameter requires setting
-    /// [`Self::og_image_base_url`] as well.
     pub serve_html: bool,
 
     /// Base URL for the service from which the OpenGraph images
@@ -184,14 +182,6 @@ impl Server {
             cdn_domain = storage.cdn_prefix.as_ref().map(|cdn_prefix| format!("https://{cdn_prefix}")).unwrap_or_default()
         );
 
-        let serve_html = var_parsed("SERVE_HTML")?.unwrap_or(true);
-        let og_image_base_url = serve_html
-            .then(|| {
-                required_var_parsed("OG_IMAGE_BASE_URL")
-                    .context("OG_IMAGE_BASE_URL must be set when using INDEX_HTML_TEMPLATE_PATH")
-            })
-            .transpose()?;
-
         Ok(Server {
             db: DatabasePools::full_from_environment(&base)?,
             storage,
@@ -236,7 +226,7 @@ impl Server {
                 .unwrap_or(StatusCodeConfig::AdjustAll),
             serve_dist: true,
             serve_html: true,
-            og_image_base_url,
+            og_image_base_url: var_parsed("OG_IMAGE_BASE_URL")?,
             html_render_cache_max_capacity: var_parsed("HTML_RENDER_CACHE_CAP")?.unwrap_or(1024),
             content_security_policy: Some(content_security_policy.parse()?),
         })

src/middleware/ember_html.rs

@@ -76,8 +76,7 @@ pub async fn serve_html(state: AppState, request: Request, next: Next) -> Respon
         // `state.config.og_image_base_url` will always be `Some` as that's required
         // if `state.config.serve_html` is `true`, and otherwise this
         // middleware won't be executed; see `crate::middleware::apply_axum_middleware`.
-        let og_image_base_url = state.config.og_image_base_url.as_ref().unwrap();
-        let og_image_url = generate_og_image_url(path, og_image_base_url);
+        let og_image_url = generate_og_image_url(path, &state.config.og_image_base_url);
 
         // Fetch the HTML from cache given `og_image_url` as key or render it
         let html = RENDERED_HTML_CACHE
@@ -125,7 +124,11 @@ fn extract_crate_name(path: &str) -> Option<&str> {
 /// Come up with an Open Graph image URL. In case a crate page is requested,
 /// we use the crate's name as extracted from the request path and the OG image
 /// base URL from config to generate one, otherwise we use the fallback image.
-fn generate_og_image_url(path: &str, og_image_base_url: &Url) -> Cow<'static, str> {
+fn generate_og_image_url(path: &str, og_image_base_url: &Option<Url>) -> Cow<'static, str> {
+    let Some(og_image_base_url) = og_image_base_url else {
+        return OG_IMAGE_FALLBACK_URL.into();
+    };
+
     if let Some(krate) = extract_crate_name(path) {
         if let Ok(og_img_url) = og_image_base_url
             .join(krate)
@@ -182,6 +185,7 @@ mod tests {
         ];
 
         let og_image_base_url: Url = "http://localhost:3000/og/".parse().unwrap();
+        let og_image_base_url = Some(og_image_base_url);
 
         for (path, expected) in PATHS.iter().copied() {
             assert_that!(