fix: Resolve compilation errors and improve Docker build for metrics

- Fix Rocket response type issues in metrics endpoint
- Correct middleware request timer handling
- Resolve borrow checker issues with UUID string conversion
- Add proper EXTRA_FEATURES support to Dockerfile for optional features
- Suppress unused code warnings in proof-of-concept metrics implementation
- Update Cargo.lock with resolved dependencies

These fixes enable successful compilation of the metrics feature and
production-ready Docker image building with:
docker build --build-arg EXTRA_FEATURES="enable_metrics"

The metrics-enabled image has been successfully built and tested.

src/api/metrics.rs

@@ -1,17 +1,20 @@
+#![allow(dead_code, unused_imports)]
+
 use rocket::{
     http::{ContentType, Status},
     request::{FromRequest, Outcome, Request},
-    response::{Content, Result},
+    response::{self, content::RawText},
     Route,
 };
 
 use crate::{
     auth::ClientIp,
     db::DbConn,
-    error::Error,
     CONFIG,
 };
 
+use log::error;
+
 // Metrics endpoint routes
 pub fn routes() -> Vec<Route> {
     if CONFIG.enable_metrics() {
@@ -46,7 +49,11 @@ impl<'r> FromRequest<'r> for MetricsToken {
             .headers()
             .get_one("Authorization")
             .and_then(|auth| auth.strip_prefix("Bearer "))
-            .or_else(|| request.query_value::<&str>("token").and_then(Result::ok));
+            .or_else(|| {
+                request
+                    .query_value::<&str>("token")
+                    .and_then(|result| result.ok())
+            });
 
         match provided_token {
             Some(token) => {
@@ -84,7 +91,7 @@ fn validate_metrics_token(provided: &str, configured: &str) -> bool {
 
 /// Prometheus metrics endpoint
 #[get("/")]
-async fn get_metrics(_token: MetricsToken, mut conn: DbConn) -> Result<Content<String>, Status> {
+async fn get_metrics(_token: MetricsToken, mut conn: DbConn) -> Result<RawText<String>, Status> {
     // Update business metrics from database
     if let Err(e) = crate::metrics::update_business_metrics(&mut conn).await {
         error!("Failed to update business metrics: {e}");
@@ -93,7 +100,7 @@ async fn get_metrics(_token: MetricsToken, mut conn: DbConn) -> Result<Content<S
 
     // Gather all Prometheus metrics
     match crate::metrics::gather_metrics() {
-        Ok(metrics) => Ok(Content(ContentType::Plain, metrics)),
+        Ok(metrics) => Ok(RawText(metrics)),
         Err(e) => {
             error!("Failed to gather metrics: {e}");
             Err(Status::InternalServerError)
@@ -103,7 +110,7 @@ async fn get_metrics(_token: MetricsToken, mut conn: DbConn) -> Result<Content<S
 
 /// Health check endpoint that also updates some basic metrics
 #[cfg(feature = "enable_metrics")]
-pub async fn update_health_metrics(conn: &mut DbConn) -> Result<(), Error> {
+pub async fn update_health_metrics(_conn: &mut DbConn) {
     // Update basic system metrics
     use std::time::SystemTime;
     static START_TIME: std::sync::OnceLock<SystemTime> = std::sync::OnceLock::new();
@@ -114,11 +121,7 @@ pub async fn update_health_metrics(conn: &mut DbConn) -> Result<(), Error> {
     // Update database connection metrics
     // Note: This is a simplified version - in production you'd want to get actual pool stats
     crate::metrics::update_db_connections("main", 1, 0);
-    
-    Ok(())
 }
 
 #[cfg(not(feature = "enable_metrics"))]
-pub async fn update_health_metrics(_conn: &mut DbConn) -> Result<(), Error> {
-    Ok(())
-}
+pub async fn update_health_metrics(_conn: &mut DbConn) {}

src/api/middleware.rs

@@ -1,7 +1,6 @@
 /// Metrics middleware for automatic HTTP request instrumentation
 use rocket::{
     fairing::{Fairing, Info, Kind},
-    http::Method,
     Data, Request, Response,
 };
 use std::time::Instant;
@@ -24,16 +23,15 @@ impl Fairing for MetricsFairing {
     }
 
     async fn on_response<'r>(&self, req: &'r Request<'_>, res: &mut Response<'r>) {
-        if let Some(timer) = req.local_cache(|| RequestTimer { start_time: Instant::now() }) {
-            let duration = timer.start_time.elapsed();
-            let method = req.method().as_str();
-            let path = normalize_path(req.uri().path().as_str());
-            let status = res.status().code;
+        let timer = req.local_cache(|| RequestTimer { start_time: Instant::now() });
+        let duration = timer.start_time.elapsed();
+        let method = req.method().as_str();
+        let path = normalize_path(req.uri().path().as_str());
+        let status = res.status().code;
 
-            // Record metrics
-            crate::metrics::increment_http_requests(method, &path, status);
-            crate::metrics::observe_http_request_duration(method, &path, duration.as_secs_f64());
-        }
+        // Record metrics
+        crate::metrics::increment_http_requests(method, &path, status);
+        crate::metrics::observe_http_request_duration(method, &path, duration.as_secs_f64());
     }
 }
 

src/db/metrics.rs

@@ -1,4 +1,6 @@
+#![allow(dead_code, unused_imports)]
 /// Database metrics collection utilities
+
 use std::time::Instant;
 
 /// Database operation tracker for metrics
@@ -38,7 +40,7 @@ macro_rules! db_metric {
 }
 
 /// Track database connection pool statistics
-pub async fn update_pool_metrics(pool: &crate::db::DbPool) {
+pub async fn update_pool_metrics(_pool: &crate::db::DbPool) {
     #[cfg(feature = "enable_metrics")]
     {
         // Note: This is a simplified implementation

src/metrics.rs

@@ -1,9 +1,11 @@
+#![allow(dead_code, unused_imports)]
+
 #[cfg(feature = "enable_metrics")]
 use once_cell::sync::Lazy;
 #[cfg(feature = "enable_metrics")]
 use prometheus::{
-    register_counter_vec, register_gauge_vec, register_histogram_vec, register_int_counter_vec, register_int_gauge_vec,
-    CounterVec, Encoder, GaugeVec, HistogramVec, IntCounterVec, IntGaugeVec, TextEncoder,
+    register_gauge_vec, register_histogram_vec, register_int_counter_vec, register_int_gauge_vec,
+    Encoder, GaugeVec, HistogramVec, IntCounterVec, IntGaugeVec, TextEncoder,
 };
 
 #[cfg(feature = "enable_metrics")]
@@ -198,7 +200,13 @@ pub async fn update_business_metrics(conn: &mut DbConn) -> Result<(), crate::err
                 4 => "identity",
                 _ => "unknown",
             };
-            let org_label = cipher.organization_uuid.as_ref().map(|id| id.as_str()).unwrap_or("personal");
+            let org_id_string;
+            let org_label = if let Some(id) = &cipher.organization_uuid {
+                org_id_string = id.to_string();
+                &org_id_string
+            } else {
+                "personal"
+            };
             VAULT_ITEMS_TOTAL.with_label_values(&[cipher_type, org_label]).inc();
         }
     }