Enable analytics in codex exec and codex mcp-server (#13083)

Addresses #12913

`codex exec` was not correctly defaulting to Otel metrics to enabled 
`codex mcp-server` completely lacked an Otel collector

Summary:
- default to enabling analytics when `codex exec` initializes
OpenTelemetry so the CLI actually reports metrics again
- add a regression test that proves the flag remains enabled by default
- added Otel collector to `codex mcp-server`

codex-rs/mcp-server/src/lib.rs

@@ -21,6 +21,7 @@ use tracing::debug;
 use tracing::error;
 use tracing::info;
 use tracing_subscriber::EnvFilter;
+use tracing_subscriber::prelude::*;
 
 mod codex_tool_config;
 mod codex_tool_runner;
@@ -45,6 +46,8 @@ pub use crate::patch_approval::PatchApprovalResponse;
 /// is a balance between throughput and memory usage – 128 messages should be
 /// plenty for an interactive CLI.
 const CHANNEL_CAPACITY: usize = 128;
+const DEFAULT_ANALYTICS_ENABLED: bool = true;
+const OTEL_SERVICE_NAME: &str = "codex_mcp_server";
 
 type IncomingMessage = JsonRpcMessage<ClientRequest, Value, ClientNotification>;
 
@@ -52,12 +55,44 @@ pub async fn run_main(
     arg0_paths: Arg0DispatchPaths,
     cli_config_overrides: CliConfigOverrides,
 ) -> IoResult<()> {
-    // Install a simple subscriber so `tracing` output is visible.  Users can
-    // control the log level with `RUST_LOG`.
-    tracing_subscriber::fmt()
+    // Parse CLI overrides once and derive the base Config eagerly so later
+    // components do not need to work with raw TOML values.
+    let cli_kv_overrides = cli_config_overrides.parse_overrides().map_err(|e| {
+        std::io::Error::new(
+            ErrorKind::InvalidInput,
+            format!("error parsing -c overrides: {e}"),
+        )
+    })?;
+    let config = Config::load_with_cli_overrides(cli_kv_overrides)
+        .await
+        .map_err(|e| {
+            std::io::Error::new(ErrorKind::InvalidData, format!("error loading config: {e}"))
+        })?;
+
+    let otel = codex_core::otel_init::build_provider(
+        &config,
+        env!("CARGO_PKG_VERSION"),
+        Some(OTEL_SERVICE_NAME),
+        DEFAULT_ANALYTICS_ENABLED,
+    )
+    .map_err(|e| {
+        std::io::Error::new(
+            ErrorKind::InvalidData,
+            format!("error loading otel config: {e}"),
+        )
+    })?;
+
+    let fmt_layer = tracing_subscriber::fmt::layer()
         .with_writer(std::io::stderr)
-        .with_env_filter(EnvFilter::from_default_env())
-        .init();
+        .with_filter(EnvFilter::from_default_env());
+    let otel_logger_layer = otel.as_ref().and_then(|provider| provider.logger_layer());
+    let otel_tracing_layer = otel.as_ref().and_then(|provider| provider.tracing_layer());
+
+    let _ = tracing_subscriber::registry()
+        .with(fmt_layer)
+        .with(otel_logger_layer)
+        .with(otel_tracing_layer)
+        .try_init();
 
     // Set up channels.
     let (incoming_tx, mut incoming_rx) = mpsc::channel::<IncomingMessage>(CHANNEL_CAPACITY);
@@ -86,20 +121,6 @@ pub async fn run_main(
         }
     });
 
-    // Parse CLI overrides once and derive the base Config eagerly so later
-    // components do not need to work with raw TOML values.
-    let cli_kv_overrides = cli_config_overrides.parse_overrides().map_err(|e| {
-        std::io::Error::new(
-            ErrorKind::InvalidInput,
-            format!("error parsing -c overrides: {e}"),
-        )
-    })?;
-    let config = Config::load_with_cli_overrides(cli_kv_overrides)
-        .await
-        .map_err(|e| {
-            std::io::Error::new(ErrorKind::InvalidData, format!("error loading config: {e}"))
-        })?;
-
     // Task: process incoming messages.
     let processor_handle = tokio::spawn({
         let outgoing_message_sender = OutgoingMessageSender::new(outgoing_tx);
@@ -152,3 +173,55 @@ pub async fn run_main(
 
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use codex_core::config::ConfigBuilder;
+    use codex_core::config::types::OtelExporterKind;
+    use pretty_assertions::assert_eq;
+    use std::collections::HashMap;
+    use tempfile::TempDir;
+
+    #[test]
+    fn mcp_server_defaults_analytics_to_enabled() {
+        assert_eq!(DEFAULT_ANALYTICS_ENABLED, true);
+    }
+
+    #[tokio::test]
+    async fn mcp_server_builds_otel_provider_with_logs_traces_and_metrics() -> anyhow::Result<()> {
+        let codex_home = TempDir::new()?;
+        let mut config = ConfigBuilder::default()
+            .codex_home(codex_home.path().to_path_buf())
+            .build()
+            .await?;
+        let exporter = OtelExporterKind::OtlpGrpc {
+            endpoint: "http://localhost:4317".to_string(),
+            headers: HashMap::new(),
+            tls: None,
+        };
+        config.otel.exporter = exporter.clone();
+        config.otel.trace_exporter = exporter.clone();
+        config.otel.metrics_exporter = exporter;
+        config.analytics_enabled = None;
+
+        let provider = codex_core::otel_init::build_provider(
+            &config,
+            "0.0.0-test",
+            Some(OTEL_SERVICE_NAME),
+            DEFAULT_ANALYTICS_ENABLED,
+        )
+        .map_err(|err| anyhow::anyhow!(err.to_string()))?
+        .expect("otel provider");
+
+        assert!(provider.logger.is_some(), "expected log exporter");
+        assert!(
+            provider.tracer_provider.is_some(),
+            "expected trace exporter"
+        );
+        assert!(provider.metrics().is_some(), "expected metrics exporter");
+        provider.shutdown();
+
+        Ok(())
+    }
+}