fix: lazy connection pools for dynamic routing service (#6437)

Co-authored-by: Nishant Joshi <nishant.joshi@juspay.in>
Co-authored-by: hyperswitch-bot[bot] <148525504+hyperswitch-bot[bot]@users.noreply.github.com>

Cargo.lock

@@ -3126,8 +3126,10 @@ dependencies = [
  "dyn-clone",
  "error-stack",
  "hex",
+ "http-body-util",
  "hyper 0.14.30",
  "hyper-proxy",
+ "hyper-util",
  "hyperswitch_interfaces",
  "masking",
  "once_cell",
@@ -3959,9 +3961,9 @@ dependencies = [
 
 [[package]]
 name = "hyper-util"
-version = "0.1.7"
+version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cde7055719c54e36e95e8719f95883f22072a48ede39db7fc17a4e1d5281e9b9"
+checksum = "41296eb09f183ac68eec06e03cdbea2e759633d4067b2f6552fc2e009bcad08b"
 dependencies = [
  "bytes 1.7.1",
  "futures-channel",
@@ -3972,7 +3974,6 @@ dependencies = [
  "pin-project-lite",
  "socket2",
  "tokio 1.40.0",
- "tower",
  "tower-service",
  "tracing",
 ]

crates/external_services/Cargo.toml

@@ -13,7 +13,7 @@ email = ["dep:aws-config"]
 aws_s3 = ["dep:aws-config", "dep:aws-sdk-s3"]
 hashicorp-vault = ["dep:vaultrs"]
 v1 = ["hyperswitch_interfaces/v1", "common_utils/v1"]
-dynamic_routing = ["dep:prost", "dep:tonic", "dep:tonic-reflection", "dep:tonic-types", "dep:api_models", "tokio/macros", "tokio/rt-multi-thread", "dep:tonic-build", "dep:router_env"]
+dynamic_routing = ["dep:prost", "dep:tonic", "dep:tonic-reflection", "dep:tonic-types", "dep:api_models", "tokio/macros", "tokio/rt-multi-thread", "dep:tonic-build", "dep:router_env", "dep:hyper-util", "dep:http-body-util"]
 
 [dependencies]
 async-trait = "0.1.79"
@@ -38,6 +38,8 @@ tokio = "1.37.0"
 tonic = { version = "0.12.2", optional = true }
 tonic-reflection = { version = "0.12.2", optional = true }
 tonic-types = { version = "0.12.2", optional = true }
+hyper-util = { version = "0.1.9", optional = true }
+http-body-util = { version = "0.1.2", optional = true }
 
 
 # First party crates

crates/external_services/src/grpc_client/dynamic_routing.rs

@@ -6,6 +6,9 @@ use api_models::routing::{
 };
 use common_utils::{errors::CustomResult, ext_traits::OptionExt, transformers::ForeignTryFrom};
 use error_stack::ResultExt;
+use http_body_util::combinators::UnsyncBoxBody;
+use hyper::body::Bytes;
+use hyper_util::client::legacy::connect::HttpConnector;
 use serde;
 use success_rate::{
     success_rate_calculator_client::SuccessRateCalculatorClient, CalSuccessRateConfig,
@@ -13,7 +16,7 @@ use success_rate::{
     CurrentBlockThreshold as DynamicCurrentThreshold, LabelWithStatus,
     UpdateSuccessRateWindowConfig, UpdateSuccessRateWindowRequest, UpdateSuccessRateWindowResponse,
 };
-use tonic::transport::Channel;
+use tonic::Status;
 #[allow(
     missing_docs,
     unused_qualifications,
@@ -40,11 +43,13 @@ pub enum DynamicRoutingError {
     SuccessRateBasedRoutingFailure(String),
 }
 
+type Client = hyper_util::client::legacy::Client<HttpConnector, UnsyncBoxBody<Bytes, Status>>;
+
 /// Type that consists of all the services provided by the client
 #[derive(Debug, Clone)]
 pub struct RoutingStrategy {
     /// success rate service for Dynamic Routing
-    pub success_rate_client: Option<SuccessRateCalculatorClient<Channel>>,
+    pub success_rate_client: Option<SuccessRateCalculatorClient<Client>>,
 }
 
 /// Contains the Dynamic Routing Client Config
@@ -68,11 +73,14 @@ impl DynamicRoutingClientConfig {
     pub async fn get_dynamic_routing_connection(
         self,
     ) -> Result<RoutingStrategy, Box<dyn std::error::Error>> {
+        let client =
+            hyper_util::client::legacy::Client::builder(hyper_util::rt::TokioExecutor::new())
+                .http2_only(true)
+                .build_http();
         let success_rate_client = match self {
             Self::Enabled { host, port } => {
-                let uri = format!("http://{}:{}", host, port);
-                let channel = tonic::transport::Endpoint::new(uri)?.connect().await?;
-                Some(SuccessRateCalculatorClient::new(channel))
+                let uri = format!("http://{}:{}", host, port).parse::<tonic::transport::Uri>()?;
+                Some(SuccessRateCalculatorClient::with_origin(client, uri))
             }
             Self::Disabled => None,
         };
@@ -102,7 +110,7 @@ pub trait SuccessBasedDynamicRouting: dyn_clone::DynClone + Send + Sync {
 }
 
 #[async_trait::async_trait]
-impl SuccessBasedDynamicRouting for SuccessRateCalculatorClient<Channel> {
+impl SuccessBasedDynamicRouting for SuccessRateCalculatorClient<Client> {
     async fn calculate_success_rate(
         &self,
         id: String,