Make the rollout knob GKE deployer specific

Right now the `rollout` knob is global, and it applies to all deployers.
However, each deployer has its own rollout story. E.g., single, multi -
no rollout story, SSH - no rollout story, kube - up to the DevOps people
how to do it.

The rollout knob makes sense only for the GKE deployer, where we have a
custom rollout strategy, so it makes sense to make the knob a GKE
deployer specific knob. However, if in the future we'll decide to add a
system component that can compute rollout strategies and it can be
applied to many deployers, we can move it back.

I will remove the `rollout` knob from the weaver repo in a followup PR.

internal/config/config.proto

@@ -77,4 +77,11 @@ message GKEConfig {
     repeated string component = 1;
   }
   map<string, Components> identity_allowlist = 10;
+
+  // A knob that lets the user specifies how many nanoseconds it expects for
+  // the rollout to take. This is used internally by the GKE deployer to figure
+  // out the rollout strategy.
+  //
+  // If not specified, Service Weaver will pick a default value.
+  int64 rollout_nanos = 11;
 }

internal/gke/deploy.go

@@ -371,7 +371,7 @@ func enableMultiClusterServices(config CloudConfig) error {
 
 func finalizeConfig(cloudConfig CloudConfig, gkeConfig *config.GKEConfig) error {
 	// Finalize the rollout duration.
-	if gkeConfig.Deployment.App.RolloutNanos == 0 {
+	if gkeConfig.RolloutNanos == 0 {
 		scanner := bufio.NewScanner(os.Stdin)
 		fmt.Print(
 			`No rollout duration specified in the config: the app version will be

internal/nanny/controller/controller.go

@@ -218,7 +218,7 @@ func (c *controller) rollout(ctx context.Context, req *RolloutRequest) error {
 	}
 
 	// Compute the rollout strategy.
-	durationHint := time.Duration(req.Config.Deployment.App.RolloutNanos)
+	durationHint := time.Duration(req.Config.RolloutNanos)
 	rolloutLocs := make([]string, len(req.Locations))
 	for i := 0; i < len(req.Locations); i++ {
 		rolloutLocs[i] = req.Locations[i].Name

internal/nanny/controller/controller_test.go

@@ -1316,13 +1316,11 @@ func registerNewAppVersion(ctx context.Context, controller *controller, v versio
 	req := &RolloutRequest{
 		Config: &config.GKEConfig{
 			Deployment: &protos.Deployment{
-				App: &protos.AppConfig{
-					Name:         v.appName,
-					RolloutNanos: int64(rollout),
-				},
-				Id: v.id,
+				App: &protos.AppConfig{Name: v.appName},
+				Id:  v.id,
 			},
-			Listeners: v.listenerOpts,
+			Listeners:    v.listenerOpts,
+			RolloutNanos: int64(rollout),
 		},
 	}
 	for _, location := range v.locations {

internal/tool/deploy.go

@@ -120,6 +120,7 @@ func makeGKEConfig(app *protos.AppConfig) (*config.GKEConfig, error) {
 		Regions   []string
 		Listeners map[string]lisOpts
 		MTLS      bool
+		Rollout   time.Duration
 	}
 	parsed := &gkeConfigSchema{}
 	if err := runtime.ParseConfigSection(gkeKey, shortGKEKey, app.Sections, parsed); err != nil {
@@ -157,7 +158,8 @@ func makeGKEConfig(app *protos.AppConfig) (*config.GKEConfig, error) {
 			App: app,
 			Id:  depID.String(),
 		},
-		Mtls: parsed.MTLS,
+		Mtls:         parsed.MTLS,
+		RolloutNanos: int64(parsed.Rollout),
 	}
 
 	return cfg, nil