feat: Allow an endpoint to serve multiple models (#2418)

Author: grahamking

components/metrics/src/main.rs

@@ -127,7 +127,7 @@ async fn app(runtime: Runtime) -> Result<()> {
     tracing::debug!("Creating unique instance of Count at {key}");
     drt.etcd_client()
         .expect("Unreachable because of DistributedRuntime::from_settings above")
-        .kv_create(key, serde_json::to_vec_pretty(&config)?, None)
+        .kv_create(&key, serde_json::to_vec_pretty(&config)?, None)
         .await
         .context("Unable to create unique instance of Count; possibly one already exists")?;
 

lib/bindings/python/rust/lib.rs

@@ -557,7 +557,7 @@ impl EtcdClient {
         let client = self.inner.clone();
         pyo3_async_runtimes::tokio::future_into_py(py, async move {
             client
-                .kv_create(key, value, lease_id)
+                .kv_create(&key, value, lease_id)
                 .await
                 .map_err(to_pyerr)?;
             Ok(())

lib/llm/src/local_model.rs

@@ -10,7 +10,7 @@ use dynamo_runtime::protocols::Endpoint as EndpointId;
 use dynamo_runtime::slug::Slug;
 use dynamo_runtime::traits::DistributedRuntimeProvider;
 use dynamo_runtime::{
-    component::{Component, Endpoint},
+    component::Endpoint,
     storage::key_value_store::{EtcdStorage, KeyValueStore, KeyValueStoreManager},
 };
 
@@ -302,8 +302,6 @@ impl LocalModel {
         let Some(etcd_client) = endpoint.drt().etcd_client() else {
             anyhow::bail!("Cannot attach to static endpoint");
         };
-        self.ensure_unique(endpoint.component(), self.display_name())
-            .await?;
 
         // Store model config files in NATS object store
         let nats_client = endpoint.drt().nats_client();
@@ -319,7 +317,7 @@ impl LocalModel {
 
         // Publish our ModelEntry to etcd. This allows ingress to find the model card.
         // (Why don't we put the model card directly under this key?)
-        let network_name = ModelNetworkName::from_local(endpoint, etcd_client.lease_id());
+        let network_name = ModelNetworkName::new();
         tracing::debug!("Registering with etcd as {network_name}");
         let model_registration = ModelEntry {
             name: self.display_name().to_string(),
@@ -328,35 +326,12 @@ impl LocalModel {
         };
         etcd_client
             .kv_create(
-                network_name.to_string(),
+                &network_name,
                 serde_json::to_vec_pretty(&model_registration)?,
                 None, // use primary lease
             )
             .await
     }
-
-    /// Ensure that each component serves only one model.
-    /// We can have multiple instances of the same model running using the same component name
-    /// (they get load balanced, and are differentiated in etcd by their lease_id).
-    /// We cannot have multiple models with the same component name.
-    ///
-    /// Returns an error if there is already a component by this name serving a different model.
-    async fn ensure_unique(&self, component: &Component, model_name: &str) -> anyhow::Result<()> {
-        let Some(etcd_client) = component.drt().etcd_client() else {
-            // A static component is necessarily unique, it cannot register
-            return Ok(());
-        };
-        for endpoint_info in component.list_instances().await? {
-            let network_name: ModelNetworkName = (&endpoint_info).into();
-
-            if let Ok(entry) = network_name.load_entry(&etcd_client).await {
-                if entry.name != model_name {
-                    anyhow::bail!("Duplicate component. Attempt to register model {model_name} at {component}, which is already used by {network_name} running model {}.", entry.name);
-                }
-            }
-        }
-        Ok(())
-    }
 }
 
 /// A random endpoint to use for internal communication

lib/llm/src/local_model/network_name.rs

@@ -1,75 +1,38 @@
 // SPDX-FileCopyrightText: Copyright (c) 2024-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-use anyhow::Context as _;
-
-use crate::discovery::{ModelEntry, MODEL_ROOT_PATH};
-use dynamo_runtime::component::{self, Instance};
-use dynamo_runtime::slug::Slug;
-use dynamo_runtime::transports::etcd;
+use crate::discovery::MODEL_ROOT_PATH;
 
 #[derive(Debug, Clone)]
 pub struct ModelNetworkName(String);
 
 impl ModelNetworkName {
-    /// Key to store this model entry in networked key-value store (etcd).
-    ///
-    /// It looks like this:
-    /// ns.cp.ep-694d967ca5efd804
-    fn from_parts(namespace: &str, component: &str, endpoint: &str, lease_id: i64) -> Self {
-        let model_root = MODEL_ROOT_PATH;
-        let slug = Slug::slugify(&format!("{namespace}.{component}.{endpoint}-{lease_id:x}"));
-        ModelNetworkName(format!("{model_root}/{slug}"))
-    }
-
-    // We can't do From<&component::Endpoint> here because we also need the lease_id
-    pub fn from_local(endpoint: &component::Endpoint, lease_id: i64) -> Self {
-        Self::from_parts(
-            &endpoint.component().namespace().to_string(),
-            &endpoint.component().name(),
-            endpoint.name(),
-            lease_id,
-        )
+    pub fn new() -> Self {
+        ModelNetworkName(format!("{MODEL_ROOT_PATH}/{}", uuid::Uuid::new_v4()))
     }
+}
 
-    pub fn from_entry(entry: &ModelEntry, lease_id: i64) -> Self {
-        Self::from_parts(
-            &entry.endpoint.namespace,
-            &entry.endpoint.component,
-            &entry.endpoint.name,
-            lease_id,
-        )
+impl Default for ModelNetworkName {
+    fn default() -> Self {
+        Self::new()
     }
+}
 
-    /// Fetch the ModelEntry from etcd.
-    pub async fn load_entry(&self, etcd_client: &etcd::Client) -> anyhow::Result<ModelEntry> {
-        let mut model_entries = etcd_client.kv_get(self.to_string(), None).await?;
-        if model_entries.is_empty() {
-            anyhow::bail!("No ModelEntry in etcd for key {self}");
-        }
-        let model_entry = model_entries.remove(0);
-        serde_json::from_slice(model_entry.value()).with_context(|| {
-            format!(
-                "Error deserializing JSON. Key={self}. JSON={}",
-                model_entry.value_str().unwrap_or("INVALID UTF-8")
-            )
-        })
+impl std::fmt::Display for ModelNetworkName {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.0)
     }
 }
 
-impl From<&Instance> for ModelNetworkName {
-    fn from(cei: &Instance) -> Self {
-        Self::from_parts(
-            &cei.namespace,
-            &cei.component,
-            &cei.endpoint,
-            cei.instance_id,
-        )
+impl AsRef<str> for ModelNetworkName {
+    fn as_ref(&self) -> &str {
+        &self.0
     }
 }
 
-impl std::fmt::Display for ModelNetworkName {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", self.0)
+impl std::ops::Deref for ModelNetworkName {
+    type Target = str;
+    fn deref(&self) -> &Self::Target {
+        &self.0
     }
 }

lib/runtime/examples/Cargo.lock

@@ -144,7 +144,7 @@ impl EndpointConfigBuilder {
         if let Some(etcd_client) = &endpoint.component.drt.etcd_client {
             if let Err(e) = etcd_client
                 .kv_create(
-                    endpoint.etcd_path_with_lease_id(lease_id),
+                    &endpoint.etcd_path_with_lease_id(lease_id),
                     info,
                     Some(lease_id),
                 )

lib/runtime/src/component/endpoint.rs

@@ -170,20 +170,15 @@ impl Client {
             .await?
     }
 
-    pub async fn kv_create(
-        &self,
-        key: String,
-        value: Vec<u8>,
-        lease_id: Option<i64>,
-    ) -> Result<()> {
+    pub async fn kv_create(&self, key: &str, value: Vec<u8>, lease_id: Option<i64>) -> Result<()> {
         let id = lease_id.unwrap_or(self.lease_id());
         let put_options = PutOptions::new().with_lease(id);
 
         // Build the transaction
         let txn = Txn::new()
-            .when(vec![Compare::version(key.as_str(), CompareOp::Equal, 0)]) // Ensure the lock does not exist
+            .when(vec![Compare::version(key, CompareOp::Equal, 0)]) // Ensure the lock does not exist
             .and_then(vec![
-                TxnOp::put(key.as_str(), value, Some(put_options)), // Create the object
+                TxnOp::put(key, value, Some(put_options)), // Create the object
             ]);
 
         // Execute the transaction

lib/runtime/src/transports/etcd.rs

@@ -95,7 +95,7 @@ fn handle_watch_event<T: DeserializeOwned>(
 /// Creates a key-value pair in etcd, returning a specific error if the key already exists
 async fn create_barrier_key<T: Serialize>(
     client: &Client,
-    key: String,
+    key: &str,
     data: T,
     lease_id: Option<i64>,
 ) -> Result<(), LeaderWorkerBarrierError> {
@@ -193,7 +193,7 @@ impl<LeaderData: Serialize + DeserializeOwned, WorkerData: Serialize + Deseriali
         lease_id: i64,
     ) -> Result<(), LeaderWorkerBarrierError> {
         let key = barrier_key(&self.barrier_id, BARRIER_DATA);
-        create_barrier_key(client, key, data, Some(lease_id)).await
+        create_barrier_key(client, &key, data, Some(lease_id)).await
     }
 
     async fn wait_for_workers(
@@ -216,10 +216,10 @@ impl<LeaderData: Serialize + DeserializeOwned, WorkerData: Serialize + Deseriali
 
             let workers = worker_result.keys().collect::<HashSet<_>>();
 
-            create_barrier_key(client, key, workers, Some(lease_id)).await?;
+            create_barrier_key(client, &key, workers, Some(lease_id)).await?;
         } else {
             let key = barrier_key(&self.barrier_id, BARRIER_ABORT);
-            create_barrier_key(client, key, (), Some(lease_id)).await?;
+            create_barrier_key(client, &key, (), Some(lease_id)).await?;
         }
 
         Ok(())
@@ -302,7 +302,7 @@ impl<LeaderData: Serialize + DeserializeOwned, WorkerData: Serialize + Deseriali
             &self.barrier_id,
             &format!("{}/{}", BARRIER_WORKER, self.worker_id),
         );
-        create_barrier_key(client, key.clone(), data, Some(lease_id)).await?;
+        create_barrier_key(client, &key, data, Some(lease_id)).await?;
         Ok(key)
     }