diff --git a/src/conf/meta.rs b/src/conf/meta.rs
index 511a232..0f49f7d 100644
--- a/src/conf/meta.rs
+++ b/src/conf/meta.rs
@@ -132,7 +132,7 @@ impl Display for IpValue {
                 #[cfg(feature = "host-ip")]
                 IpValue::HostIp => {
                     Self::get_all_addrs()
-                        .get(0)
+                        .first()
                         .map(|s| Cow::Owned(s.to_string()))
                         .unwrap_or(Cow::Borrowed("127.0.0.1"))
                 }
diff --git a/src/conf/mod.rs b/src/conf/mod.rs
index 0277743..34bab72 100644
--- a/src/conf/mod.rs
+++ b/src/conf/mod.rs
@@ -263,10 +263,10 @@ impl ApolloConfClient {
     ///     Ok(())
     /// }
     /// ```
-    pub fn watch<'a>(
-        &'a self,
+    pub fn watch(
+        &self,
         request: WatchRequest,
-    ) -> impl Stream<Item = ApolloClientResult<HashMap<String, ApolloClientResult<FetchResponse>>>> + 'a
+    ) -> impl Stream<Item = ApolloClientResult<HashMap<String, ApolloClientResult<FetchResponse>>>> + '_
     {
         let mut watch_notifications = request.create_notifications();
         let mut fetch_notifications = watch_notifications.clone();
diff --git a/src/conf/requests.rs b/src/conf/requests.rs
index 5ffc59c..61970e0 100644
--- a/src/conf/requests.rs
+++ b/src/conf/requests.rs
@@ -42,6 +42,7 @@ impl Default for CachedFetchRequest {
     }
 }
 
+#[cfg(feature = "conf")]
 impl PerformRequest for CachedFetchRequest {
     type Response = Properties;
 
@@ -69,13 +70,14 @@ impl PerformRequest for CachedFetchRequest {
         Ok(pairs)
     }
 
+    #[cfg(all(feature = "auth", feature = "conf"))]
     fn app_id(&self) -> Option<&str> {
         Some(&self.app_id)
     }
 
-    #[cfg(feature = "auth")]
+    #[cfg(all(feature = "auth", feature = "conf"))]
     fn access_key(&self) -> Option<&str> {
-        self.access_key.as_ref().map(|key| key.as_str())
+        self.access_key.as_deref()
     }
 }
 
@@ -129,6 +131,7 @@ impl FetchRequest {
     }
 }
 
+#[cfg(feature = "conf")]
 impl PerformRequest for FetchRequest {
     type Response = FetchResponse;
 
@@ -159,13 +162,14 @@ impl PerformRequest for FetchRequest {
         Ok(pairs)
     }
 
+    #[cfg(all(feature = "auth", feature = "conf"))]
     fn app_id(&self) -> Option<&str> {
         Some(&self.app_id)
     }
 
-    #[cfg(feature = "auth")]
+    #[cfg(all(feature = "auth", feature = "conf"))]
     fn access_key(&self) -> Option<&str> {
-        self.access_key.as_ref().map(|key| key.as_str())
+        self.access_key.as_deref()
     }
 }
 
@@ -213,6 +217,7 @@ impl NotifyRequest {
     }
 }
 
+#[cfg(feature = "conf")]
 impl PerformRequest for NotifyRequest {
     type Response = Vec<Notification>;
 
@@ -243,13 +248,14 @@ impl PerformRequest for NotifyRequest {
         request_builder.timeout(self.timeout)
     }
 
+    #[cfg(all(feature = "auth", feature = "conf"))]
     fn app_id(&self) -> Option<&str> {
         Some(&self.app_id)
     }
 
-    #[cfg(feature = "auth")]
+    #[cfg(all(feature = "auth", feature = "conf"))]
     fn access_key(&self) -> Option<&str> {
-        self.access_key.as_ref().map(|key| key.as_str())
+        self.access_key.as_deref()
     }
 }
 
diff --git a/src/errors.rs b/src/errors.rs
index 416a183..894a97a 100644
--- a/src/errors.rs
+++ b/src/errors.rs
@@ -1,6 +1,8 @@
 //! Crate level errors.
 
+#[cfg(feature = "conf")]
 use http::StatusCode;
+#[cfg(feature = "conf")]
 use reqwest::Response;
 use std::str::Utf8Error;
 
@@ -27,6 +29,7 @@ pub enum ApolloClientError {
     #[error(transparent)]
     IniParse(#[from] ini::ParseError),
 
+    #[cfg(feature = "conf")]
     #[error(transparent)]
     ApolloResponse(#[from] ApolloResponseError),
 
@@ -38,6 +41,7 @@ pub enum ApolloClientError {
 }
 
 /// Apollo api response error, when http status is not success.
+#[cfg(feature = "conf")]
 #[derive(thiserror::Error, Debug)]
 #[error(r#"error occurred when apollo response, status: {status}, body: "{body}""#)]
 pub struct ApolloResponseError {
@@ -47,6 +51,7 @@ pub struct ApolloResponseError {
     pub body: String,
 }
 
+#[cfg(feature = "conf")]
 impl ApolloResponseError {
     pub(crate) async fn from_response(response: Response) -> Result<Response, Self> {
         if response.status().is_success() {
diff --git a/src/meta.rs b/src/meta.rs
index 8e90b92..b40a999 100644
--- a/src/meta.rs
+++ b/src/meta.rs
@@ -1,11 +1,10 @@
 //! Common api metadata.
 
+#[cfg(feature = "conf")]
 use crate::errors::{ApolloClientResult, ApolloResponseError};
-use async_trait::async_trait;
-use http::Method;
+#[cfg(feature = "conf")]
 use reqwest::{RequestBuilder, Response};
-use std::{borrow::Cow, fmt, fmt::Display, time::Duration};
-use url::Url;
+use std::{fmt, fmt::Display, time::Duration};
 
 #[allow(dead_code)]
 pub(crate) const DEFAULT_CLUSTER_NAME: &str = "default";
@@ -57,6 +56,7 @@ impl Display for NamespaceKind {
 }
 
 /// Common api request trait.
+#[cfg(feature = "conf")]
 pub(crate) trait PerformRequest {
     /// The returned response after request is success.
     type Response: PerformResponse;
@@ -66,11 +66,13 @@ pub(crate) trait PerformRequest {
 
     /// Request method.
     fn method(&self) -> http::Method {
-        Method::GET
+        http::Method::GET
     }
 
     /// Url queries.
-    fn queries(&self) -> ApolloClientResult<Vec<(Cow<'_, str>, Cow<'_, str>)>> {
+    fn queries(
+        &self,
+    ) -> ApolloClientResult<Vec<(std::borrow::Cow<'_, str>, std::borrow::Cow<'_, str>)>> {
         Ok(vec![])
     }
 
@@ -87,6 +89,7 @@ pub(crate) trait PerformRequest {
     }
 
     /// AppId
+    #[cfg(all(feature = "auth", feature = "conf"))]
     fn app_id(&self) -> Option<&str> {
         None
     }
@@ -139,13 +142,15 @@ pub(crate) trait PerformRequest {
 }
 
 /// Common api response trait.
-#[async_trait]
+#[cfg(feature = "conf")]
+#[async_trait::async_trait]
 pub(crate) trait PerformResponse: Sized {
     /// Create Self from response.
     async fn from_response(response: Response) -> ApolloClientResult<Self>;
 }
 
-#[async_trait]
+#[cfg(feature = "conf")]
+#[async_trait::async_trait]
 impl PerformResponse for () {
     async fn from_response(_response: Response) -> ApolloClientResult<Self> {
         Ok(())
@@ -153,7 +158,7 @@ impl PerformResponse for () {
 }
 
 #[cfg(feature = "conf")]
-#[async_trait]
+#[async_trait::async_trait]
 impl PerformResponse for ini::Properties {
     async fn from_response(response: Response) -> ApolloClientResult<Self> {
         let content = response.text().await?;
@@ -165,8 +170,11 @@ impl PerformResponse for ini::Properties {
 }
 
 /// Create request url from base url, mainly path and queries.
-#[allow(dead_code)]
-pub(crate) fn handle_url(request: &impl PerformRequest, base_url: Url) -> ApolloClientResult<Url> {
+#[cfg(feature = "conf")]
+pub(crate) fn handle_url(
+    request: &impl PerformRequest,
+    base_url: url::Url,
+) -> ApolloClientResult<url::Url> {
     let mut url = base_url;
     let path = &request.path();
     let query = &request.queries()?;
@@ -182,7 +190,7 @@ pub(crate) fn handle_url(request: &impl PerformRequest, base_url: Url) -> Apollo
 }
 
 /// Validate response is successful or not.
-#[allow(dead_code)]
+#[cfg(feature = "conf")]
 pub(crate) async fn validate_response(response: Response) -> ApolloClientResult<Response> {
     ApolloResponseError::from_response(response)
         .await
@@ -190,7 +198,7 @@ pub(crate) async fn validate_response(response: Response) -> ApolloClientResult<
 }
 
 /// Implement PerformResponse for response struct which content type is `application/json`.
-#[allow(unused_macros)]
+#[cfg(feature = "conf")]
 macro_rules! implement_json_perform_response_for {
     ($t:ty) => {
         #[async_trait::async_trait]
diff --git a/src/open/requests.rs b/src/open/requests.rs
index 7a3aa5b..49f2d96 100644
--- a/src/open/requests.rs
+++ b/src/open/requests.rs
@@ -15,7 +15,7 @@ use http::Method;
 use reqwest::RequestBuilder;
 use std::borrow::Cow;
 
-const OPEN_API_PREFIX: &'static str = "openapi/v1";
+const OPEN_API_PREFIX: &str = "openapi/v1";
 
 /// Request executed by [crate::open::OpenApiClient::execute];
 pub(crate) trait PerformOpenRequest: PerformRequest {}
@@ -49,17 +49,11 @@ impl PerformRequest for OpenEnvClusterRequest {
 impl PerformOpenRequest for OpenEnvClusterRequest {}
 
 /// Fetch app infos.
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Default)]
 pub struct OpenAppRequest {
     pub app_ids: Option<Vec<String>>,
 }
 
-impl Default for OpenAppRequest {
-    fn default() -> Self {
-        OpenAppRequest { app_ids: None }
-    }
-}
-
 impl PerformRequest for OpenAppRequest {
     type Response = Vec<OpenAppResponse>;
 
diff --git a/src/utils.rs b/src/utils.rs
index b25b906..e711066 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -28,7 +28,7 @@ pub(crate) fn get_all_addrs() -> &'static [std::net::IpAddr] {
             .map(|networks| {
                 networks
                     .values()
-                    .map(|network| {
+                    .flat_map(|network| {
                         network
                             .addrs
                             .iter()
@@ -50,7 +50,6 @@ pub(crate) fn get_all_addrs() -> &'static [std::net::IpAddr] {
                                 _ => None,
                             })
                     })
-                    .flatten()
                     .collect()
             })
             .unwrap_or_default()
diff --git a/tests/common.rs b/tests/common.rs
index d5eeccd..9b51f16 100644
--- a/tests/common.rs
+++ b/tests/common.rs
@@ -97,7 +97,7 @@ fn setup_mysql() {
 
     let mut cmd = Command::new("mysql");
     let output = cmd
-        .args(&["-h", "127.0.0.1", "-u", "root"])
+        .args(["-h", "127.0.0.1", "-u", "root"])
         .stdin(sql_file)
         .output()
         .unwrap();