diff --git a/src/cmd/src/metasrv.rs b/src/cmd/src/metasrv.rs
index dc455dcf65..da017e71cd 100644
--- a/src/cmd/src/metasrv.rs
+++ b/src/cmd/src/metasrv.rs
@@ -132,7 +132,7 @@ impl SubCommand {
 }
 
 #[derive(Debug, Default, Parser)]
-struct StartCommand {
+pub struct StartCommand {
     /// The address to bind the gRPC server.
     #[clap(long, alias = "bind-addr")]
     rpc_bind_addr: Option<String>,
@@ -172,7 +172,7 @@ struct StartCommand {
 }
 
 impl StartCommand {
-    fn load_options(&self, global_options: &GlobalOptions) -> Result<MetasrvOptions> {
+    pub fn load_options(&self, global_options: &GlobalOptions) -> Result<MetasrvOptions> {
         let mut opts = MetasrvOptions::load_layered_options(
             self.config_file.as_deref(),
             self.env_prefix.as_ref(),
@@ -261,7 +261,7 @@ impl StartCommand {
         Ok(())
     }
 
-    async fn build(&self, opts: MetasrvOptions) -> Result<Instance> {
+    pub async fn build(&self, opts: MetasrvOptions) -> Result<Instance> {
         common_runtime::init_global_runtimes(&opts.runtime);
 
         let guard = common_telemetry::init_global_logging(
diff --git a/src/meta-srv/src/lib.rs b/src/meta-srv/src/lib.rs
index 4b61eeeae3..ebd3b7b54f 100644
--- a/src/meta-srv/src/lib.rs
+++ b/src/meta-srv/src/lib.rs
@@ -31,6 +31,7 @@ pub mod metasrv;
 pub mod metrics;
 #[cfg(feature = "mock")]
 pub mod mocks;
+pub mod node_excluder;
 pub mod procedure;
 pub mod pubsub;
 pub mod region;
diff --git a/src/meta-srv/src/node_excluder.rs b/src/meta-srv/src/node_excluder.rs
new file mode 100644
index 0000000000..f9e892f092
--- /dev/null
+++ b/src/meta-srv/src/node_excluder.rs
@@ -0,0 +1,26 @@
+// Copyright 2023 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::sync::Arc;
+
+use common_meta::DatanodeId;
+
+pub type NodeExcluderRef = Arc<dyn NodeExcluder>;
+
+/// [NodeExcluder] is used to help decide whether some nodes should be excluded (out of consideration)
+/// in certain situations. For example, in some node selectors.
+pub trait NodeExcluder: Send + Sync {
+    /// Returns the excluded datanode ids.
+    fn excluded_datanode_ids(&self) -> &Vec<DatanodeId>;
+}
diff --git a/typos.toml b/typos.toml
index da6570d224..57b7279d0f 100644
--- a/typos.toml
+++ b/typos.toml
@@ -6,6 +6,7 @@ ot = "ot"
 typ = "typ"
 typs = "typs"
 unqualifed = "unqualifed"
+excluder = "excluder"
 
 [files]
 extend-exclude = [