Remove Prometheus metrics, keeping only OTEL

Cargo.toml

@@ -49,7 +49,6 @@ opentelemetry_sdk = { version = "0.31", default-features = false, features = [
     "logs",
     "metrics",
 ] }
-prometheus = "0.14"
 s3s = "0.13.0-alpha.3"
 s3s-aws = "0.13.0-alpha.3"
 tokio = { version = "1", features = [

src/config.rs

@@ -87,10 +87,6 @@ pub struct Config {
     /// Export logs via OTLP gRPC (requires otel_grpc_endpoint_url)
     #[arg(long, env = "OTEL_EXPORT_LOGS", default_value_t = false, action = clap::ArgAction::Set)]
     pub otel_export_logs: bool,
-
-    /// Prometheus textfile collector directory
-    #[arg(long, env = "PROMETHEUS_TEXTFILE_DIR")]
-    pub prometheus_textfile_dir: Option<String>,
 }
 
 impl Config {
@@ -141,7 +137,7 @@ impl Display for Config {
              cache_max_entries: {}, cache_max_size_bytes: {}, cache_ttl_seconds: {}, \
              max_cacheable_object_size: {}, otel_grpc_endpoint_url: {:?}, \
              otel_export_metrics: {}, otel_export_logs: {}, cache_shards: {}, \
-             cache_dry_run: {}, worker_threads: {}, prometheus_textfile_dir: {:?} }}",
+             cache_dry_run: {}, worker_threads: {} }}",
             self.listen_addr,
             self.upstream_endpoint,
             self.upstream_region,
@@ -155,7 +151,6 @@ impl Display for Config {
             self.cache_shards,
             self.cache_dry_run,
             self.worker_threads,
-            self.prometheus_textfile_dir,
         )
     }
 }
@@ -186,7 +181,6 @@ mod tests {
             otel_grpc_endpoint_url: None,
             otel_export_metrics: false,
             otel_export_logs: false,
-            prometheus_textfile_dir: None,
         }
     }
 

src/lib.rs

@@ -12,7 +12,7 @@
 //! - **Range Request Support**: Caches partial object reads (byte ranges)
 //! - **Cache Invalidation**: Automatic invalidation on PUT/DELETE operations
 //! - **Dry-run Mode**: Validate cache correctness without serving cached data
-//! - **Telemetry**: OpenTelemetry metrics and Prometheus support
+//! - **Telemetry**: OpenTelemetry metrics support
 
 use std::sync::Arc;
 use std::time::Duration;
@@ -41,7 +41,6 @@ mod auth;
 mod config;
 mod error;
 mod fifo_cache;
-mod metrics_writer;
 mod proxy;
 mod s3_cache;
 mod s3_op;
@@ -157,24 +156,6 @@ where
         S3CachingServiceProxy::new(b.build(), upstream_health_endpoint)
     };
 
-    // Start Prometheus metrics writer if configured
-    let metrics_writer_handle = if let Some(textfile_dir) = config.prometheus_textfile_dir.clone() {
-        info!(
-            "Starting Prometheus textfile writer to {}/s3_cache.prom",
-            textfile_dir
-        );
-        Some(tokio::spawn({
-            async move {
-                if let Err(e) = metrics_writer::start_metrics_writer(textfile_dir).await {
-                    error!("Metrics writer failed: {:?}", e);
-                }
-            }
-        }))
-    } else {
-        info!("Prometheus textfile writer disabled (PROMETHEUS_TEXTFILE_DIR not set)");
-        None
-    };
-
     // Start hyper server
     let listener = TcpListener::bind(config.listen_addr).await?;
     // Report the bound address before entering the accept loop so callers using
@@ -223,12 +204,6 @@ where
         }
     }
 
-    // Abort metrics writer background task
-    if let Some(handle) = metrics_writer_handle {
-        handle.abort();
-        info!("Metrics writer task aborted");
-    }
-
     telemetry::shutdown_metrics(metrics_provider);
     telemetry::shutdown_logs(logs_provider);