feat(routing): build gRPC Client Interface to initiate communication with other gRPC services (#5835)

Co-authored-by: prajjwalkumar17 <prajjwal.kumar@juspay.in>
Co-authored-by: hyperswitch-bot[bot] <148525504+hyperswitch-bot[bot]@users.noreply.github.com>
Co-authored-by: Nishant Joshi <nishant.joshi@juspay.in>

crates/external_services/src/grpc_client.rs

@@ -0,0 +1,48 @@
+/// Dyanimc Routing Client interface implementation
+#[cfg(feature = "dynamic_routing")]
+pub mod dynamic_routing;
+use std::{fmt::Debug, sync::Arc};
+
+#[cfg(feature = "dynamic_routing")]
+use dynamic_routing::{DynamicRoutingClientConfig, RoutingStrategy};
+use router_env::logger;
+use serde;
+
+/// Struct contains all the gRPC Clients
+#[derive(Debug, Clone)]
+pub struct GrpcClients {
+    /// The routing client
+    #[cfg(feature = "dynamic_routing")]
+    pub dynamic_routing: RoutingStrategy,
+}
+/// Type that contains the configs required to construct a  gRPC client with its respective services.
+#[derive(Debug, Clone, serde::Deserialize, serde::Serialize, Default)]
+pub struct GrpcClientSettings {
+    #[cfg(feature = "dynamic_routing")]
+    /// Configs for Dynamic Routing Client
+    pub dynamic_routing_client: DynamicRoutingClientConfig,
+}
+
+impl GrpcClientSettings {
+    /// # Panics
+    ///
+    /// This function will panic if it fails to establish a connection with the gRPC server.
+    /// This function will be called at service startup.
+    #[allow(clippy::expect_used)]
+    pub async fn get_grpc_client_interface(&self) -> Arc<GrpcClients> {
+        #[cfg(feature = "dynamic_routing")]
+        let dynamic_routing_connection = self
+            .dynamic_routing_client
+            .clone()
+            .get_dynamic_routing_connection()
+            .await
+            .expect("Failed to establish a connection with the Dynamic Routing Server");
+
+        logger::info!("Connection established with gRPC Server");
+
+        Arc::new(GrpcClients {
+            #[cfg(feature = "dynamic_routing")]
+            dynamic_routing: dynamic_routing_connection,
+        })
+    }
+}