Port activation flags with dynamic registration (#29237)

changelog/29237.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+core: Add activation flags. A mechanism for users to opt in to new functionality at a convenient time. Previously used only in Enterprise for SecretSync, activation flags are now available in CE for future features to use.
+```

helper/activationflags/activation_flags.go

@@ -0,0 +1,142 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package activationflags
+
+import (
+	"context"
+	"fmt"
+	"maps"
+	"sync"
+
+	"github.com/hashicorp/vault/sdk/logical"
+)
+
+const (
+	storagePathActivationFlags = "activation-flags"
+)
+
+type FeatureActivationFlags struct {
+	activationFlagsLock sync.RWMutex
+	storage             logical.Storage
+	activationFlags     map[string]bool
+}
+
+func NewFeatureActivationFlags() *FeatureActivationFlags {
+	return &FeatureActivationFlags{
+		activationFlags: map[string]bool{},
+	}
+}
+
+func (f *FeatureActivationFlags) Initialize(ctx context.Context, storage logical.Storage) error {
+	f.activationFlagsLock.Lock()
+	defer f.activationFlagsLock.Unlock()
+
+	if storage == nil {
+		return fmt.Errorf("unable to access storage")
+	}
+
+	f.storage = storage
+
+	entry, err := f.storage.Get(ctx, storagePathActivationFlags)
+	if err != nil {
+		return fmt.Errorf("failed to get activation flags from storage: %w", err)
+	}
+	if entry == nil {
+		f.activationFlags = map[string]bool{}
+		return nil
+	}
+
+	var activationFlags map[string]bool
+	if err := entry.DecodeJSON(&activationFlags); err != nil {
+		return fmt.Errorf("failed to decode activation flags from storage: %w", err)
+	}
+
+	f.activationFlags = activationFlags
+
+	return nil
+}
+
+// Get is the helper function called by the activation-flags API read endpoint. This reads the
+// actual values from storage, then updates the in-memory cache of the activation-flags. It
+// returns a slice of the feature names which have already been activated.
+func (f *FeatureActivationFlags) Get(ctx context.Context) ([]string, error) {
+	f.activationFlagsLock.Lock()
+	defer f.activationFlagsLock.Unlock()
+
+	// Don't use nil slice declaration, we want the JSON to show "[]" instead of null
+	activated := []string{}
+
+	if f.storage == nil {
+		return activated, nil
+	}
+
+	entry, err := f.storage.Get(ctx, storagePathActivationFlags)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get activation flags from storage: %w", err)
+	}
+	if entry == nil {
+		return activated, nil
+	}
+
+	var activationFlags map[string]bool
+	if err := entry.DecodeJSON(&activationFlags); err != nil {
+		return nil, fmt.Errorf("failed to decode activation flags from storage: %w", err)
+	}
+
+	// Update the in-memory flags after loading the latest values from storage
+	f.activationFlags = activationFlags
+
+	for flag, set := range activationFlags {
+		if set {
+			activated = append(activated, flag)
+		}
+	}
+
+	return activated, nil
+}
+
+// Write is the helper function called by the activation-flags API write endpoint. This stores
+// the boolean value for the activation-flag feature name into Vault storage across the cluster
+// and updates the in-memory cache upon success.
+func (f *FeatureActivationFlags) Write(ctx context.Context, featureName string, activate bool) (err error) {
+	f.activationFlagsLock.Lock()
+	defer f.activationFlagsLock.Unlock()
+
+	if f.storage == nil {
+		return fmt.Errorf("unable to access storage")
+	}
+
+	activationFlags := f.activationFlags
+
+	clonedFlags := maps.Clone(f.activationFlags)
+	clonedFlags[featureName] = activate
+	// The cloned flags are updated but the in-memory state is only updated on success of the storage update.
+	defer func() {
+		if err == nil {
+			activationFlags[featureName] = activate
+		}
+	}()
+
+	entry, err := logical.StorageEntryJSON(storagePathActivationFlags, clonedFlags)
+	if err != nil {
+		return fmt.Errorf("failed to marshal object to JSON: %w", err)
+	}
+
+	err = f.storage.Put(ctx, entry)
+	if err != nil {
+		return fmt.Errorf("failed to save object in storage: %w", err)
+	}
+
+	return nil
+}
+
+// IsActivationFlagEnabled is true if the specified flag is enabled in the core.
+func (f *FeatureActivationFlags) IsActivationFlagEnabled(featureName string) bool {
+	f.activationFlagsLock.RLock()
+	defer f.activationFlagsLock.RUnlock()
+
+	activated, ok := f.activationFlags[featureName]
+
+	return ok && activated
+}

vault/core.go

@@ -45,6 +45,7 @@ import (
 	"github.com/hashicorp/vault/api"
 	"github.com/hashicorp/vault/audit"
 	"github.com/hashicorp/vault/command/server"
+	"github.com/hashicorp/vault/helper/activationflags"
 	"github.com/hashicorp/vault/helper/identity/mfa"
 	"github.com/hashicorp/vault/helper/locking"
 	"github.com/hashicorp/vault/helper/metricsutil"
@@ -739,6 +740,9 @@ type Core struct {
 	clusterAddrBridge *raft.ClusterAddrBridge
 
 	censusManager *CensusManager
+
+	// Activation flags for enterprise features that require a one-time activation
+	FeatureActivationFlags *activationflags.FeatureActivationFlags
 }
 
 func (c *Core) ActiveNodeClockSkewMillis() int64 {
@@ -1448,11 +1452,14 @@ func (c *Core) configureLogicalBackends(backends map[string]logical.Factory, log
 	// System
 	logicalBackends[mountTypeSystem] = func(ctx context.Context, config *logical.BackendConfig) (logical.Backend, error) {
 		sysBackendLogger := logger.Named("system")
+
 		c.AddLogger(sysBackendLogger)
 		b := NewSystemBackend(c, sysBackendLogger, config)
+
 		if err := b.Setup(ctx, config); err != nil {
 			return nil, err
 		}
+
 		return b, nil
 	}
 

vault/core_util.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 
 	"github.com/hashicorp/go-hclog"
+	"github.com/hashicorp/vault/helper/activationflags"
 	"github.com/hashicorp/vault/helper/namespace"
 	"github.com/hashicorp/vault/limits"
 	"github.com/hashicorp/vault/sdk/helper/license"
@@ -59,6 +60,8 @@ func coreInit(c *Core, conf *CoreConfig) error {
 		c.physical = physical.NewStorageEncoding(c.physical)
 	}
 
+	c.FeatureActivationFlags = activationflags.NewFeatureActivationFlags()
+
 	return nil
 }
 

vault/logical_system.go

@@ -231,6 +231,7 @@ func NewSystemBackend(core *Core, logger log.Logger, config *logical.BackendConf
 	b.Backend.Paths = append(b.Backend.Paths, b.experimentPaths()...)
 	b.Backend.Paths = append(b.Backend.Paths, b.introspectionPaths()...)
 	b.Backend.Paths = append(b.Backend.Paths, b.wellKnownPaths()...)
+	b.Backend.Paths = append(b.Backend.Paths, b.activationFlagsPaths()...)
 
 	if core.rawEnabled {
 		b.Backend.Paths = append(b.Backend.Paths, b.rawPaths()...)

vault/logical_system_activation_flags.go

@@ -0,0 +1,140 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package vault
+
+import (
+	"context"
+	"fmt"
+	"slices"
+	"strings"
+
+	"github.com/hashicorp/vault/sdk/framework"
+	"github.com/hashicorp/vault/sdk/logical"
+)
+
+const (
+	paramFeatureName = "feature_name"
+	descFeatureName  = "The name of the feature to be activated."
+	summaryList      = "Returns the available and activated activation-flagged features."
+	summaryUpdate    = "Activate a flagged feature."
+
+	prefixActivationFlags         = "activation-flags"
+	verbActivationFlagsActivate   = "activate"
+	verbActivationFlagsDeactivate = "deactivate"
+
+	fieldActivated   = "activated"
+	fieldUnactivated = "unactivated"
+
+	helpSynopsis    = "Returns information about Vault's features that require a one-time activation step."
+	helpDescription = `
+This path responds to the following HTTP methods.
+	GET /
+		Returns the available and activated activation-flags.
+
+	PUT|POST /<feature-name>/activate
+		Activates the specified feature. Cannot be undone.`
+)
+
+// Register CRUD functions dynamically.
+// These variables should only be mutated during initialization or server construction.
+// It is unsafe to modify them once the Vault core is running.
+var (
+	readActivationFlag = func(ctx context.Context, b *SystemBackend, req *logical.Request, fd *framework.FieldData) (*logical.Response, error) {
+		return b.readActivationFlag(ctx, req, fd)
+	}
+
+	writeActivationFlag = func(ctx context.Context, b *SystemBackend, req *logical.Request, fd *framework.FieldData, isActivate bool) (*logical.Response, error) {
+		return b.writeActivationFlagWrite(ctx, req, fd, isActivate)
+	}
+)
+
+func (b *SystemBackend) activationFlagsPaths() []*framework.Path {
+	return []*framework.Path{
+		{
+			Pattern: fmt.Sprintf("%s$", prefixActivationFlags),
+			DisplayAttrs: &framework.DisplayAttributes{
+				OperationVerb:   "read",
+				OperationSuffix: prefixActivationFlags,
+			},
+			Operations: map[logical.Operation]framework.OperationHandler{
+				logical.ReadOperation: &framework.PathOperation{
+					Callback: b.handleActivationFlagRead,
+					Summary:  summaryList,
+				},
+			},
+			HelpSynopsis:    helpSynopsis,
+			HelpDescription: helpDescription,
+		},
+		{
+			Pattern: fmt.Sprintf("%s/%s/%s", prefixActivationFlags, "activation-test", verbActivationFlagsActivate),
+			DisplayAttrs: &framework.DisplayAttributes{
+				OperationPrefix: prefixActivationFlags,
+				OperationVerb:   verbActivationFlagsActivate,
+			},
+			Operations: map[logical.Operation]framework.OperationHandler{
+				logical.UpdateOperation: &framework.PathOperation{
+					Callback:                    b.handleActivationFlagsActivate,
+					ForwardPerformanceSecondary: true,
+					ForwardPerformanceStandby:   true,
+					Summary:                     summaryUpdate,
+				},
+			},
+			HelpSynopsis:    helpSynopsis,
+			HelpDescription: helpDescription,
+		},
+	}
+}
+
+func (b *SystemBackend) handleActivationFlagRead(ctx context.Context, req *logical.Request, fd *framework.FieldData) (*logical.Response, error) {
+	return readActivationFlag(ctx, b, req, fd)
+}
+
+func (b *SystemBackend) handleActivationFlagsActivate(ctx context.Context, req *logical.Request, data *framework.FieldData) (*logical.Response, error) {
+	return writeActivationFlag(ctx, b, req, data, true)
+}
+
+func (b *SystemBackend) readActivationFlag(ctx context.Context, req *logical.Request, _ *framework.FieldData) (*logical.Response, error) {
+	activationFlags, err := b.Core.FeatureActivationFlags.Get(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	return b.activationFlagsToResponse(activationFlags), nil
+}
+
+func (b *SystemBackend) writeActivationFlagWrite(ctx context.Context, req *logical.Request, _ *framework.FieldData, isActivate bool) (*logical.Response, error) {
+	// We need to manually parse out the feature_name from the path because we can't use FieldSchema parameters
+	// in the path to make generic endpoints. We need each activation-flag path to be a separate endpoint.
+	// Path starts out as activation-flags/<feature_name>/verb
+	// Removes activation-flags/ from the path
+	trimPrefix := strings.TrimPrefix(req.Path, prefixActivationFlags+"/")
+	// Removes /verb from the path
+	featureName := trimPrefix[:strings.LastIndex(trimPrefix, "/")]
+
+	err := b.Core.FeatureActivationFlags.Write(ctx, featureName, isActivate)
+	if err != nil {
+		return nil, fmt.Errorf("failed to write new activation flags: %w", err)
+	}
+
+	// We read back the value after writing it to storage so that we can try forcing a cache update right away.
+	// If this fails, it's still okay to proceed as the write has been successful and the cache will get updated
+	// at the time of an endpoint getting called. However, we can only return the one feature name we just activated
+	// in the response since the read to retrieve any others did not succeed.
+	activationFlags, err := b.Core.FeatureActivationFlags.Get(ctx)
+	if err != nil {
+		resp := b.activationFlagsToResponse([]string{featureName})
+		return resp, fmt.Errorf("failed to read activation-flags back after write: %w", err)
+	}
+
+	return b.activationFlagsToResponse(activationFlags), nil
+}
+
+func (b *SystemBackend) activationFlagsToResponse(activationFlags []string) *logical.Response {
+	slices.Sort(activationFlags)
+	return &logical.Response{
+		Data: map[string]interface{}{
+			fieldActivated: activationFlags,
+		},
+	}
+}