grafana-iam: Adds config opts for RBACRemoteClient for load balancing (#110819)

pkg/services/authz/README.md

@@ -31,6 +31,13 @@ listen = false
 mode = "inproc"
 ```
 
+For load balancing you would want to enable the load balancing configuration. This sets sane default for multiple pods to be evenly distributed with load across the different pods.
+
+```ini
+[authorization]
+load_balancing_enabled = true
+```
+
 ### Example
 
 Here is an example to connect the authorization client to a remote grpc server.

pkg/services/authz/rbac.go

@@ -180,6 +180,16 @@ func newRemoteRBACClient(clientCfg *authzClientSettings, tracer trace.Tracer, re
 		grpc.WithChainStreamInterceptor(streamInterceptors...),
 	}
 
+	// // if we serve the client as a load balancer
+	if clientCfg.loadBalancingEnabled {
+		// Use round_robin to balances requests more evenly over the available Grafana replicas.
+		opts = append(opts, grpc.WithDefaultServiceConfig(`{"loadBalancingPolicy": "round_robin"}`))
+
+		// Disable looking up service config from TXT DNS records.
+		// This reduces the number of requests made to the DNS servers.
+		opts = append(opts, grpc.WithDisableServiceConfig())
+	}
+
 	conn, err := grpc.NewClient(clientCfg.remoteAddress, opts...)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create authz client to remote server: %w", err)

pkg/services/authz/rbac_settings.go

@@ -23,9 +23,10 @@ const (
 )
 
 type authzClientSettings struct {
-	remoteAddress string
-	certFile      string
-	mode          clientMode
+	remoteAddress        string
+	certFile             string
+	mode                 clientMode
+	loadBalancingEnabled bool
 
 	token            string
 	tokenExchangeURL string
@@ -51,6 +52,7 @@ func readAuthzClientSettings(cfg *setting.Cfg) (*authzClientSettings, error) {
 	if s.mode == clientModeInproc {
 		return s, nil
 	}
+	s.loadBalancingEnabled = authzSection.Key("load_balancing_enabled").MustBool(false)
 
 	s.remoteAddress = authzSection.Key("remote_address").MustString("")
 	s.certFile = authzSection.Key("cert_file").MustString("")