service: allow services to have defined stability levels (#6674)

This commit adds stability levels to services. Every service, with the
exception of remotecfg, is then given a stability level of stable.
remotecfg is given a stability level of "beta."

internal/component/registry.go

@@ -124,7 +124,7 @@ type Registration struct {
 	// sure the user is not accidentally using a component that is not yet stable - users
 	// need to explicitly enable less-than-stable components via, for example, a command-line flag.
 	// If a component is not stable enough, an attempt to create it via the controller will fail.
-	// The default stability level is Experimental.
+	// This field must be set to a non-zero value.
 	Stability featuregate.Stability
 
 	// An example Arguments value that the registered component expects to

internal/flow/flow_services_test.go

@@ -63,6 +63,7 @@ func TestServices_Configurable(t *testing.T) {
 				return service.Definition{
 					Name:       "fake",
 					ConfigType: ServiceOptions{},
+					Stability:  featuregate.StabilityBeta,
 				}
 			},
 
@@ -117,6 +118,7 @@ func TestServices_Configurable_Optional(t *testing.T) {
 				return service.Definition{
 					Name:       "fake",
 					ConfigType: ServiceOptions{},
+					Stability:  featuregate.StabilityBeta,
 				}
 			},
 

internal/flow/internal/controller/loader.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/go-kit/log"
+	"github.com/grafana/agent/internal/featuregate"
 	"github.com/grafana/agent/internal/flow/internal/dag"
 	"github.com/grafana/agent/internal/flow/internal/worker"
 	"github.com/grafana/agent/internal/flow/logging/level"
@@ -441,6 +442,19 @@ func (l *Loader) populateServiceNodes(g *dag.Graph, serviceBlocks []*ast.BlockSt
 
 		node := g.GetByID(blockID).(*ServiceNode)
 
+		// Don't permit configuring services that have a lower stability level than
+		// what is currently enabled.
+		nodeStability := node.Service().Definition().Stability
+		if err := featuregate.CheckAllowed(nodeStability, l.globals.MinStability, fmt.Sprintf("block %q", blockID)); err != nil {
+			diags.Add(diag.Diagnostic{
+				Severity: diag.SeverityLevelError,
+				Message:  err.Error(),
+				StartPos: ast.StartPos(block).Position(),
+				EndPos:   ast.EndPos(block).Position(),
+			})
+			continue
+		}
+
 		// Blocks assigned to services are reset to nil in the previous loop.
 		//
 		// If the block is non-nil, it means that there was a duplicate block

internal/flow/internal/controller/loader_test.go

@@ -1,6 +1,7 @@
 package controller_test
 
 import (
+	"context"
 	"errors"
 	"os"
 	"strings"
@@ -11,6 +12,7 @@ import (
 	"github.com/grafana/agent/internal/flow/internal/controller"
 	"github.com/grafana/agent/internal/flow/internal/dag"
 	"github.com/grafana/agent/internal/flow/logging"
+	"github.com/grafana/agent/internal/service"
 	"github.com/grafana/river/ast"
 	"github.com/grafana/river/diag"
 	"github.com/grafana/river/parser"
@@ -316,6 +318,60 @@ func TestLoader(t *testing.T) {
 	})
 }
 
+func TestLoader_Services(t *testing.T) {
+	testFile := `
+		testsvc { }
+	`
+
+	testService := &fakeService{
+		DefinitionFunc: func() service.Definition {
+			return service.Definition{
+				Name: "testsvc",
+				ConfigType: struct {
+					Name string `river:"name,attr,optional"`
+				}{},
+				Stability: featuregate.StabilityBeta,
+			}
+		},
+	}
+
+	newLoaderOptionsWithStability := func(stability featuregate.Stability) controller.LoaderOptions {
+		l, _ := logging.New(os.Stderr, logging.DefaultOptions)
+		return controller.LoaderOptions{
+			ComponentGlobals: controller.ComponentGlobals{
+				Logger:            l,
+				TraceProvider:     noop.NewTracerProvider(),
+				DataPath:          t.TempDir(),
+				MinStability:      stability,
+				OnBlockNodeUpdate: func(cn controller.BlockNode) { /* no-op */ },
+				Registerer:        prometheus.NewRegistry(),
+				NewModuleController: func(id string) controller.ModuleController {
+					return nil
+				},
+			},
+			Services: []service.Service{testService},
+		}
+	}
+
+	t.Run("Load with service at correct stability level", func(t *testing.T) {
+		l := controller.NewLoader(newLoaderOptionsWithStability(featuregate.StabilityBeta))
+		diags := applyFromContent(t, l, []byte(testFile), nil, nil)
+		require.NoError(t, diags.ErrorOrNil())
+	})
+
+	t.Run("Load with service below minimum stabilty level", func(t *testing.T) {
+		l := controller.NewLoader(newLoaderOptionsWithStability(featuregate.StabilityStable))
+		diags := applyFromContent(t, l, []byte(testFile), nil, nil)
+		require.ErrorContains(t, diags.ErrorOrNil(), `block "testsvc" is at stability level "beta", which is below the minimum allowed stability level "stable"`)
+	})
+
+	t.Run("Load with undefined minimum stability level", func(t *testing.T) {
+		l := controller.NewLoader(newLoaderOptionsWithStability(featuregate.StabilityUndefined))
+		diags := applyFromContent(t, l, []byte(testFile), nil, nil)
+		require.ErrorContains(t, diags.ErrorOrNil(), `stability levels must be defined: got "beta" as stability of block "testsvc" and <invalid_stability_level> as the minimum stability level`)
+	})
+}
+
 // TestScopeWithFailingComponent is used to ensure that the scope is filled out, even if the component
 // fails to properly start.
 func TestScopeWithFailingComponent(t *testing.T) {
@@ -473,3 +529,37 @@ func (f fakeModuleController) ClearModuleIDs() {
 func (f fakeModuleController) NewCustomComponent(id string, export component.ExportFunc) (controller.CustomComponent, error) {
 	return nil, nil
 }
+
+type fakeService struct {
+	DefinitionFunc func() service.Definition // Required.
+	RunFunc        func(ctx context.Context, host service.Host) error
+	UpdateFunc     func(newConfig any) error
+	DataFunc       func() any
+}
+
+func (fs *fakeService) Definition() service.Definition {
+	return fs.DefinitionFunc()
+}
+
+func (fs *fakeService) Run(ctx context.Context, host service.Host) error {
+	if fs.RunFunc != nil {
+		return fs.RunFunc(ctx, host)
+	}
+
+	<-ctx.Done()
+	return nil
+}
+
+func (fs *fakeService) Update(newConfig any) error {
+	if fs.UpdateFunc != nil {
+		return fs.UpdateFunc(newConfig)
+	}
+	return nil
+}
+
+func (fs *fakeService) Data() any {
+	if fs.DataFunc != nil {
+		return fs.DataFunc()
+	}
+	return nil
+}

internal/service/cluster/cluster.go

@@ -15,6 +15,7 @@ import (
 
 	"github.com/go-kit/log"
 	"github.com/grafana/agent/internal/component"
+	"github.com/grafana/agent/internal/featuregate"
 	"github.com/grafana/agent/internal/flow/logging/level"
 	"github.com/grafana/agent/internal/service"
 	http_service "github.com/grafana/agent/internal/service/http"
@@ -162,6 +163,7 @@ func (s *Service) Definition() service.Definition {
 			// Cluster depends on the HTTP service to work properly.
 			http_service.ServiceName,
 		},
+		Stability: featuregate.StabilityStable,
 	}
 }
 

internal/service/http/http.go

@@ -16,6 +16,7 @@ import (
 	"github.com/go-kit/log"
 	"github.com/gorilla/mux"
 	"github.com/grafana/agent/internal/component"
+	"github.com/grafana/agent/internal/featuregate"
 	"github.com/grafana/agent/internal/flow"
 	"github.com/grafana/agent/internal/flow/logging/level"
 	"github.com/grafana/agent/internal/service"
@@ -128,6 +129,7 @@ func (s *Service) Definition() service.Definition {
 		Name:       ServiceName,
 		ConfigType: Arguments{},
 		DependsOn:  nil, // http has no dependencies.
+		Stability:  featuregate.StabilityStable,
 	}
 }
 

internal/service/labelstore/service.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/go-kit/log"
+	"github.com/grafana/agent/internal/featuregate"
 	"github.com/grafana/agent/internal/flow/logging/level"
 	agent_service "github.com/grafana/agent/internal/service"
 	flow_service "github.com/grafana/agent/internal/service"
@@ -67,6 +68,7 @@ func (s *service) Definition() agent_service.Definition {
 		Name:       ServiceName,
 		ConfigType: Arguments{},
 		DependsOn:  nil,
+		Stability:  featuregate.StabilityStable,
 	}
 }
 

internal/service/otel/otel.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 
 	"github.com/go-kit/log"
+	"github.com/grafana/agent/internal/featuregate"
 	"github.com/grafana/agent/internal/service"
 	"github.com/grafana/agent/internal/util"
 )
@@ -50,6 +51,7 @@ func (*Service) Definition() service.Definition {
 		Name:       ServiceName,
 		ConfigType: nil, // otel does not accept configuration
 		DependsOn:  []string{},
+		Stability:  featuregate.StabilityStable,
 	}
 }
 

internal/service/remotecfg/remotecfg.go

@@ -17,6 +17,7 @@ import (
 	"github.com/grafana/agent-remote-config/api/gen/proto/go/agent/v1/agentv1connect"
 	"github.com/grafana/agent/internal/agentseed"
 	"github.com/grafana/agent/internal/component/common/config"
+	"github.com/grafana/agent/internal/featuregate"
 	"github.com/grafana/agent/internal/flow/logging/level"
 	"github.com/grafana/agent/internal/service"
 	"github.com/grafana/river"
@@ -128,6 +129,7 @@ func (s *Service) Definition() service.Definition {
 		Name:       ServiceName,
 		ConfigType: Arguments{},
 		DependsOn:  nil, // remotecfg has no dependencies.
+		Stability:  featuregate.StabilityBeta,
 	}
 }
 

internal/service/service.go

@@ -11,6 +11,7 @@ import (
 	"fmt"
 
 	"github.com/grafana/agent/internal/component"
+	"github.com/grafana/agent/internal/featuregate"
 )
 
 // Definition describes an individual Flow service. Services have unique names
@@ -35,6 +36,14 @@ type Definition struct {
 	// or a named service doesn't exist), it is treated as a fatal
 	// error and the root Flow module will exit.
 	DependsOn []string
+
+	// Stability is the overall stability level of the service. This is used to
+	// make sure the user is not accidentally configuring a service that is not
+	// yet stable - users need to explicitly enable less-than-stable services
+	// via, for example, a command-line flag. If a service is not stable enough,
+	// an attempt to configure it via the controller will fail.
+	// This field must be set to a non-zero value.
+	Stability featuregate.Stability
 }
 
 // Host is a controller for services and Flow components.

internal/service/ui/ui.go

@@ -8,6 +8,7 @@ import (
 	"path"
 
 	"github.com/gorilla/mux"
+	"github.com/grafana/agent/internal/featuregate"
 	"github.com/grafana/agent/internal/service"
 	http_service "github.com/grafana/agent/internal/service/http"
 	"github.com/grafana/agent/internal/web/api"
@@ -46,6 +47,7 @@ func (s *Service) Definition() service.Definition {
 		Name:       ServiceName,
 		ConfigType: nil, // ui does not accept configuration
 		DependsOn:  []string{http_service.ServiceName},
+		Stability:  featuregate.StabilityStable,
 	}
 }