endpoint_storage: add ?from_endpoint= to /lfc/prewarm (#12195)

Related: https://github.com/neondatabase/cloud/issues/24225
Add optional from_endpoint parameter to allow prewarming from other
endpoint

Cargo.lock

@@ -753,6 +753,7 @@ dependencies = [
  "axum",
  "axum-core",
  "bytes",
+ "form_urlencoded",
  "futures-util",
  "headers",
  "http 1.1.0",
@@ -761,6 +762,8 @@ dependencies = [
  "mime",
  "pin-project-lite",
  "serde",
+ "serde_html_form",
+ "serde_path_to_error",
  "tower 0.5.2",
  "tower-layer",
  "tower-service",
@@ -6422,6 +6425,19 @@ dependencies = [
  "syn 2.0.100",
 ]
 
+[[package]]
+name = "serde_html_form"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d2de91cf02bbc07cde38891769ccd5d4f073d22a40683aa4bc7a95781aaa2c4"
+dependencies = [
+ "form_urlencoded",
+ "indexmap 2.9.0",
+ "itoa",
+ "ryu",
+ "serde",
+]
+
 [[package]]
 name = "serde_json"
 version = "1.0.125"

Cargo.toml

@@ -71,7 +71,7 @@ aws-credential-types = "1.2.0"
 aws-sigv4 = { version = "1.2", features = ["sign-http"] }
 aws-types = "1.3"
 axum = { version = "0.8.1", features = ["ws"] }
-axum-extra = { version = "0.10.0", features = ["typed-header"] }
+axum-extra = { version = "0.10.0", features = ["typed-header", "query"] }
 base64 = "0.13.0"
 bincode = "1.3"
 bindgen = "0.71"

compute_tools/src/compute.rs

@@ -785,7 +785,7 @@ impl ComputeNode {
         self.spawn_extension_stats_task();
 
         if pspec.spec.autoprewarm {
-            self.prewarm_lfc();
+            self.prewarm_lfc(None);
         }
         Ok(())
     }

compute_tools/src/compute_prewarm.rs

@@ -25,11 +25,16 @@ struct EndpointStoragePair {
 }
 
 const KEY: &str = "lfc_state";
-impl TryFrom<&crate::compute::ParsedSpec> for EndpointStoragePair {
+impl EndpointStoragePair {
-    type Error = anyhow::Error;
+    /// endpoint_id is set to None while prewarming from other endpoint, see replica promotion
-    fn try_from(pspec: &crate::compute::ParsedSpec) -> Result<Self, Self::Error> {
+    /// If not None, takes precedence over pspec.spec.endpoint_id
-        let Some(ref endpoint_id) = pspec.spec.endpoint_id else {
+    fn from_spec_and_endpoint(
-            bail!("pspec.endpoint_id missing")
+        pspec: &crate::compute::ParsedSpec,
+        endpoint_id: Option<String>,
+    ) -> Result<Self> {
+        let endpoint_id = endpoint_id.as_ref().or(pspec.spec.endpoint_id.as_ref());
+        let Some(ref endpoint_id) = endpoint_id else {
+            bail!("pspec.endpoint_id missing, other endpoint_id not provided")
         };
         let Some(ref base_uri) = pspec.endpoint_storage_addr else {
             bail!("pspec.endpoint_storage_addr missing")
@@ -84,7 +89,7 @@ impl ComputeNode {
     }
 
     /// Returns false if there is a prewarm request ongoing, true otherwise
-    pub fn prewarm_lfc(self: &Arc<Self>) -> bool {
+    pub fn prewarm_lfc(self: &Arc<Self>, from_endpoint: Option<String>) -> bool {
         crate::metrics::LFC_PREWARM_REQUESTS.inc();
         {
             let state = &mut self.state.lock().unwrap().lfc_prewarm_state;
@@ -97,7 +102,7 @@ impl ComputeNode {
 
         let cloned = self.clone();
         spawn(async move {
-            let Err(err) = cloned.prewarm_impl().await else {
+            let Err(err) = cloned.prewarm_impl(from_endpoint).await else {
                 cloned.state.lock().unwrap().lfc_prewarm_state = LfcPrewarmState::Completed;
                 return;
             };
@@ -109,13 +114,14 @@ impl ComputeNode {
         true
     }
 
-    fn endpoint_storage_pair(&self) -> Result<EndpointStoragePair> {
+    /// from_endpoint: None for endpoint managed by this compute_ctl
+    fn endpoint_storage_pair(&self, from_endpoint: Option<String>) -> Result<EndpointStoragePair> {
         let state = self.state.lock().unwrap();
-        state.pspec.as_ref().unwrap().try_into()
+        EndpointStoragePair::from_spec_and_endpoint(state.pspec.as_ref().unwrap(), from_endpoint)
     }
 
-    async fn prewarm_impl(&self) -> Result<()> {
+    async fn prewarm_impl(&self, from_endpoint: Option<String>) -> Result<()> {
-        let EndpointStoragePair { url, token } = self.endpoint_storage_pair()?;
+        let EndpointStoragePair { url, token } = self.endpoint_storage_pair(from_endpoint)?;
         info!(%url, "requesting LFC state from endpoint storage");
 
         let request = Client::new().get(&url).bearer_auth(token);
@@ -173,7 +179,7 @@ impl ComputeNode {
     }
 
     async fn offload_lfc_impl(&self) -> Result<()> {
-        let EndpointStoragePair { url, token } = self.endpoint_storage_pair()?;
+        let EndpointStoragePair { url, token } = self.endpoint_storage_pair(None)?;
         info!(%url, "requesting LFC state from postgres");
 
         let mut compressed = Vec::new();

compute_tools/src/http/routes/lfc.rs

@@ -2,6 +2,7 @@ use crate::compute_prewarm::LfcPrewarmStateWithProgress;
 use crate::http::JsonResponse;
 use axum::response::{IntoResponse, Response};
 use axum::{Json, http::StatusCode};
+use axum_extra::extract::OptionalQuery;
 use compute_api::responses::LfcOffloadState;
 type Compute = axum::extract::State<std::sync::Arc<crate::compute::ComputeNode>>;
 
@@ -16,8 +17,16 @@ pub(in crate::http) async fn offload_state(compute: Compute) -> Json<LfcOffloadS
     Json(compute.lfc_offload_state())
 }
 
-pub(in crate::http) async fn prewarm(compute: Compute) -> Response {
+#[derive(serde::Deserialize)]
-    if compute.prewarm_lfc() {
+pub struct PrewarmQuery {
+    pub from_endpoint: String,
+}
+
+pub(in crate::http) async fn prewarm(
+    compute: Compute,
+    OptionalQuery(query): OptionalQuery<PrewarmQuery>,
+) -> Response {
+    if compute.prewarm_lfc(query.map(|q| q.from_endpoint)) {
         StatusCode::ACCEPTED.into_response()
     } else {
         JsonResponse::error(

test_runner/fixtures/endpoint/http.py

@@ -69,8 +69,10 @@ class EndpointHttpClient(requests.Session):
         json: dict[str, str] = res.json()
         return json
 
-    def prewarm_lfc(self):
+    def prewarm_lfc(self, from_endpoint_id: str | None = None):
-        self.post(f"http://localhost:{self.external_port}/lfc/prewarm").raise_for_status()
+        url: str = f"http://localhost:{self.external_port}/lfc/prewarm"
+        params = {"from_endpoint": from_endpoint_id} if from_endpoint_id else dict()
+        self.post(url, params=params).raise_for_status()
 
         def prewarmed():
             json = self.prewarm_lfc_status()

test_runner/regress/test_lfc_prewarm.py

@@ -188,7 +188,8 @@ def test_lfc_prewarm_under_workload(neon_simple_env: NeonEnv, query: LfcQueryMet
             pg_cur.execute("select pg_reload_conf()")
 
             if query is LfcQueryMethod.COMPUTE_CTL:
-                http_client.prewarm_lfc()
+                # Same thing as prewarm_lfc(), testing other method
+                http_client.prewarm_lfc(endpoint.endpoint_id)
             else:
                 pg_cur.execute("select prewarm_local_cache(%s)", (lfc_state,))