keda-scheduler is optional feature (off by default)

ballista/scheduler/Cargo.toml

@@ -36,6 +36,7 @@ path = "src/bin/main.rs"
 [features]
 default = []
 flight-sql = []
+keda-scaler = []
 prometheus-metrics = ["prometheus", "once_cell"]
 
 

ballista/scheduler/src/scheduler_process.rs

@@ -32,6 +32,7 @@ use crate::config::SchedulerConfig;
 #[cfg(feature = "flight-sql")]
 use crate::flight_sql::FlightSqlServiceImpl;
 use crate::metrics::default_metrics_collector;
+#[cfg(feature = "keda-scaler")]
 use crate::scheduler_server::externalscaler::external_scaler_server::ExternalScalerServer;
 use crate::scheduler_server::SchedulerServer;
 
@@ -68,11 +69,11 @@ pub async fn start_server(
         .max_encoding_message_size(config.grpc_server_max_encoding_message_size as usize)
         .max_decoding_message_size(config.grpc_server_max_decoding_message_size as usize);
 
-    let keda_scaler = ExternalScalerServer::new(scheduler_server.clone());
+    let tonic_builder = create_grpc_server().add_service(scheduler_grpc_server);
 
-    let tonic_builder = create_grpc_server()
-        .add_service(scheduler_grpc_server)
-        .add_service(keda_scaler);
+    #[cfg(feature = "keda-scaler")]
+    let tonic_builder =
+        tonic_builder.add_service(ExternalScalerServer::new(scheduler_server.clone()));
 
     #[cfg(feature = "flight-sql")]
     let tonic_builder = tonic_builder.add_service(FlightServiceServer::new(

ballista/scheduler/src/scheduler_server/mod.rs

@@ -44,12 +44,14 @@ use crate::state::task_manager::TaskLauncher;
 use crate::state::SchedulerState;
 
 // include the generated protobuf source as a submodule
+#[cfg(feature = "keda-scaler")]
 #[allow(clippy::all)]
 pub mod externalscaler {
     include!(concat!(env!("OUT_DIR"), "/externalscaler.rs"));
 }
 
 pub mod event;
+#[cfg(feature = "keda-scaler")]
 mod external_scaler;
 mod grpc;
 pub(crate) mod query_stage_scheduler;