allow discovery polling interval to be configurable

crates/ott-balancer/Cargo.toml

@@ -14,6 +14,7 @@ futures-util.workspace = true
 hyper.workspace = true
 hyper-util.workspace = true
 http-body-util.workspace = true
+humantime-serde.workspace = true
 jemallocator.workspace = true
 rand.workspace = true
 reqwest.workspace = true

crates/ott-common/src/discovery/dns.rs

@@ -15,6 +15,9 @@ pub struct DnsDiscoveryConfig {
     pub dns_server: Option<SocketAddr>,
     /// The A record to query. If using docker-compose, this should be the service name for the monolith.
     pub query: String,
+    /// The configurable polling mode discovery interval, in seconds.
+    #[serde(with = "humantime_serde")]
+    pub polling_interval: Option<Duration>,
 }
 
 pub struct DnsServiceDiscoverer {
@@ -59,7 +62,11 @@ impl ServiceDiscoverer for DnsServiceDiscoverer {
     }
 
     fn mode(&self) -> DiscoveryMode {
-        DiscoveryMode::Polling(Duration::from_secs(10))
+        DiscoveryMode::Polling(
+            self.config
+                .polling_interval
+                .unwrap_or_else(|| Duration::from_secs(10)),
+        )
     }
 }
 #[cfg(test)]

crates/ott-common/src/discovery/fly.rs

@@ -1,4 +1,5 @@
 use async_trait::async_trait;
+use serde::Deserialize;
 use hickory_resolver::TokioAsyncResolver;
 use tracing::info;
 
@@ -9,6 +10,9 @@ pub struct FlyDiscoveryConfig {
     /// The port that monoliths should be listening on for load balancer connections.
     pub service_port: u16,
     pub fly_app: String,
+    /// The configurable polling mode discovery interval, in seconds.
+    #[serde(with = "humantime_serde")]
+    pub polling_interval: Option<Duration>,
 }
 
 pub struct FlyServiceDiscoverer {
@@ -46,6 +50,10 @@ impl ServiceDiscoverer for FlyServiceDiscoverer {
     }
 
     fn mode(&self) -> DiscoveryMode {
-        DiscoveryMode::Polling(Duration::from_secs(10))
+        DiscoveryMode::Polling(
+            self.config
+                .polling_interval
+                .unwrap_or_else(|| Duration::from_secs(10)),
+        )
     }
 }