diff --git a/src/cmd/src/frontend.rs b/src/cmd/src/frontend.rs
index f8c6af218a..75779690d2 100644
--- a/src/cmd/src/frontend.rs
+++ b/src/cmd/src/frontend.rs
@@ -2,6 +2,7 @@ use clap::Parser;
 use frontend::frontend::{Frontend, FrontendOptions};
 use frontend::grpc::GrpcOptions;
 use frontend::influxdb::InfluxdbOptions;
+use frontend::instance::Instance;
 use frontend::mysql::MysqlOptions;
 use frontend::opentsdb::OpentsdbOptions;
 use frontend::postgres::PostgresOptions;
@@ -56,7 +57,7 @@ struct StartCommand {
 impl StartCommand {
     async fn run(self) -> Result<()> {
         let opts = self.try_into()?;
-        let mut frontend = Frontend::new(opts);
+        let mut frontend = Frontend::new(opts, Instance::new());
         frontend.start().await.context(error::StartFrontendSnafu)
     }
 }
diff --git a/src/frontend/src/frontend.rs b/src/frontend/src/frontend.rs
index 47fe7bf405..306f92a1a6 100644
--- a/src/frontend/src/frontend.rs
+++ b/src/frontend/src/frontend.rs
@@ -6,7 +6,7 @@ use snafu::prelude::*;
 use crate::error::{self, Result};
 use crate::grpc::GrpcOptions;
 use crate::influxdb::InfluxdbOptions;
-use crate::instance::Instance;
+use crate::instance::FrontendInstance;
 use crate::mysql::MysqlOptions;
 use crate::opentsdb::OpentsdbOptions;
 use crate::postgres::PostgresOptions;
@@ -45,14 +45,19 @@ impl FrontendOptions {
     }
 }
 
-pub struct Frontend {
+pub struct Frontend<T>
+where
+    T: FrontendInstance,
+{
     opts: FrontendOptions,
-    instance: Option<Instance>,
+    instance: Option<T>,
 }
 
-impl Frontend {
-    pub fn new(opts: FrontendOptions) -> Self {
-        let instance = Instance::new();
+impl<T> Frontend<T>
+where
+    T: FrontendInstance,
+{
+    pub fn new(opts: FrontendOptions, instance: T) -> Self {
         Self {
             opts,
             instance: Some(instance),
diff --git a/src/frontend/src/instance.rs b/src/frontend/src/instance.rs
index 5d72af5099..d840222a59 100644
--- a/src/frontend/src/instance.rs
+++ b/src/frontend/src/instance.rs
@@ -3,7 +3,6 @@ mod opentsdb;
 mod prometheus;
 
 use std::collections::HashMap;
-use std::sync::Arc;
 
 use api::helper::ColumnDataTypeWrapper;
 use api::v1::{
@@ -17,7 +16,10 @@ use common_error::prelude::BoxedError;
 use common_query::Output;
 use datatypes::schema::ColumnSchema;
 use servers::error as server_error;
-use servers::query_handler::{GrpcAdminHandler, GrpcQueryHandler, SqlQueryHandler};
+use servers::query_handler::{
+    GrpcAdminHandler, GrpcQueryHandler, InfluxdbLineProtocolHandler, OpentsdbProtocolHandler,
+    PrometheusProtocolHandler, SqlQueryHandler,
+};
 use snafu::prelude::*;
 use sql::ast::{ColumnDef, TableConstraint};
 use sql::statements::create_table::{CreateTable, TIME_INDEX};
@@ -28,7 +30,20 @@ use sql::{dialect::GenericDialect, parser::ParserContext};
 use crate::error::{self, ConvertColumnDefaultConstraintSnafu, Result};
 use crate::frontend::FrontendOptions;
 
-pub(crate) type InstanceRef = Arc<Instance>;
+#[async_trait]
+pub trait FrontendInstance:
+    GrpcAdminHandler
+    + GrpcQueryHandler
+    + SqlQueryHandler
+    + OpentsdbProtocolHandler
+    + InfluxdbLineProtocolHandler
+    + PrometheusProtocolHandler
+    + Send
+    + Sync
+    + 'static
+{
+    async fn start(&mut self, opts: &FrontendOptions) -> Result<()>;
+}
 
 #[derive(Default)]
 pub struct Instance {
@@ -36,16 +51,10 @@ pub struct Instance {
 }
 
 impl Instance {
-    pub(crate) fn new() -> Self {
+    pub fn new() -> Self {
         Default::default()
     }
 
-    pub(crate) async fn start(&mut self, opts: &FrontendOptions) -> Result<()> {
-        let addr = opts.datanode_grpc_addr();
-        self.client.start(vec![addr]);
-        Ok(())
-    }
-
     // TODO(fys): temporarily hard code
     pub fn database(&self) -> Database {
         Database::new("greptime", self.client.clone())
@@ -57,6 +66,15 @@ impl Instance {
     }
 }
 
+#[async_trait]
+impl FrontendInstance for Instance {
+    async fn start(&mut self, opts: &FrontendOptions) -> Result<()> {
+        let addr = opts.datanode_grpc_addr();
+        self.client.start(vec![addr]);
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 impl Instance {
     pub fn with_client(client: Client) -> Self {
diff --git a/src/frontend/src/server.rs b/src/frontend/src/server.rs
index 882c671bb4..72a0eb31de 100644
--- a/src/frontend/src/server.rs
+++ b/src/frontend/src/server.rs
@@ -14,13 +14,16 @@ use tokio::try_join;
 use crate::error::{self, Result};
 use crate::frontend::FrontendOptions;
 use crate::influxdb::InfluxdbOptions;
-use crate::instance::InstanceRef;
+use crate::instance::FrontendInstance;
 use crate::prometheus::PrometheusOptions;
 
 pub(crate) struct Services;
 
 impl Services {
-    pub(crate) async fn start(opts: &FrontendOptions, instance: InstanceRef) -> Result<()> {
+    pub(crate) async fn start<T>(opts: &FrontendOptions, instance: Arc<T>) -> Result<()>
+    where
+        T: FrontendInstance,
+    {
         let grpc_server_and_addr = if let Some(opts) = &opts.grpc_options {
             let grpc_addr = parse_addr(&opts.addr)?;