apply max path config during early networking (#9954)

When `mgd` starts up it has a default "bestpath fanout" value of 1. We
added the ability to configure this to other values in R18, and nexus
does configure it once it's up and running, but we didn't add the call
to configure it during early networking. While ECMP isn't critical
during the early networking phase, it makes sense to keep the
environment consistent throughout the various phases of operation.

Author: internet-diglett

sled-agent/src/bootstrap/early_networking.rs

@@ -17,7 +17,8 @@ use internal_dns_types::names::ServiceName;
 use mg_admin_client::Client as MgdClient;
 use mg_admin_client::types::{
     AddStaticRoute4Request, AddStaticRoute6Request, ApplyRequest,
-    CheckerSource, ImportExportPolicy4 as MgImportExportPolicy4,
+    BestpathFanoutRequest, CheckerSource,
+    ImportExportPolicy4 as MgImportExportPolicy4,
     ImportExportPolicy6 as MgImportExportPolicy6, JitterRange, ShaperSource,
     StaticRoute4, StaticRoute4List, StaticRoute6, StaticRoute6List,
 };
@@ -691,6 +692,10 @@ impl<'a> EarlyNetworkSetup<'a> {
                         .collect(),
                 };
 
+                let fanout = BestpathFanoutRequest {
+                    fanout: config.max_paths.as_nonzero_u8(),
+                };
+
                 if let Err(e) = mgd.bgp_apply_v2(&request).await {
                     error!(
                         self.log,
@@ -699,6 +704,15 @@ impl<'a> EarlyNetworkSetup<'a> {
                         "configuration" => ?request,
                     );
                 }
+
+                if let Err(e) = mgd.update_rib_bestpath_fanout(&fanout).await {
+                    error!(
+                        self.log,
+                        "error while updating bestpath fanout";
+                        "error" => ?e,
+                        "configuration" => ?fanout,
+                    );
+                }
             }
         }