Anonymous: Add configurable device limit

[ShashankFC]

Test 1nn

Summary by CodeRabbit

Release Notes

• New Features
  • Added a new configurable anonymous device limit setting that allows fine-grained control over the maximum number of devices permitted to register with anonymous authentication
  • When the configured limit is reached, further registration attempts are automatically rejected and an appropriate error is returned to the requesting client

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nn---n*Replicated from [ai-code-review-evaluation/grafana-coderabbit#1](https://github.com/ai-code-review-evaluation/grafana-coderabbit/pull/1)*

[Copilot]

Pull request overview

This PR adds a configurable device limit for anonymous authentication to prevent unlimited device registration. When the limit is reached, new device registration attempts will be rejected with an appropriate error.

Changes:

• Added AnonymousDeviceLimit configuration field that can be set via the auth.anonymous.device_limit INI setting
• Modified the anonymous device store to enforce the limit by only allowing updates (not new registrations) when the limit is reached
• Changed TagDevice error handling from asynchronous/fire-and-forget to synchronous to properly propagate device limit errors

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pkg/setting/setting.go	Added AnonymousDeviceLimit configuration field and refactored anonymous settings parsing to use a section variable
pkg/services/anonymous/anonimpl/impl_test.go	Updated test setup to pass db.DB directly instead of pre-instantiated AnonDBStore
pkg/services/anonymous/anonimpl/impl.go	Modified ProvideAnonymousDeviceService to instantiate AnonDBStore with the device limit and added error propagation in TagDevice
pkg/services/anonymous/anonimpl/client.go	Changed device tagging from async goroutine to synchronous call with device limit error handling
pkg/services/anonymous/anonimpl/api/api.go	Renamed constant from thirtyDays to anonymousDeviceExpiration for consistency
pkg/services/anonymous/anonimpl/anonstore/database_test.go	Updated all test instantiations of AnonDBStore to include device limit parameter and added test for limit enforcement
pkg/services/anonymous/anonimpl/anonstore/database.go	Added device limit enforcement logic with new updateDevice method and ErrDeviceLimitReached error
pkg/api/frontendsettings.go	Exposed AnonymousDeviceLimit to frontend settings
pkg/api/dtos/frontend_settings.go	Added AnonymousDeviceLimit field to frontend settings DTO
packages/grafana-runtime/src/config.ts	Added anonymousDeviceLimit to runtime configuration
packages/grafana-data/src/types/config.ts	Added anonymousDeviceLimit type definition to config interface

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[Copilot]

The updateDevice method returns ErrDeviceLimitReached when no rows are affected (line 96), but this is misleading. If rowsAffected == 0, it means the device doesn't exist or the time window condition wasn't met, not that the device limit was reached. This error should only be returned from the limit check in CreateOrUpdateDevice (lines 115-116). Consider returning a different error here (e.g., ErrDeviceNotFound or ErrDeviceUpdateFailed) or allowing the upsert logic to proceed to create the device.

[Copilot]

This queries the database to count devices on every CreateOrUpdateDevice call when deviceLimit > 0, even for existing device updates. This could create a performance bottleneck under high load. Consider caching the count or only performing this check when attempting to create a new device (after checking if the device already exists).

Suggested change

	func (s *AnonDBStore) CreateOrUpdateDevice(ctx context.Context, device *Device) error {
	var query string
	// if device limit is reached, only update devices
	if s.deviceLimit > 0 {
	count, err := s.CountDevices(ctx, time.Now().UTC().Add(-anonymousDeviceExpiration), time.Now().UTC().Add(time.Minute))
	if err != nil {
	return err
	}
	if count >= s.deviceLimit {
	return s.updateDevice(ctx, device)
	}
	func (s *AnonDBStore) deviceExists(ctx context.Context, deviceID string) (bool, error) {
	const query = `SELECT 1 FROM anon_device WHERE device_id = ? LIMIT 1`
	var exists bool
	err := s.sqlStore.WithDbSession(ctx, func(dbSession *sqlstore.DBSession) error {
	rows, err := dbSession.Query(query, deviceID)
	if err != nil {
	return err
	}
	defer rows.Close()
	exists = rows.Next()
	return rows.Err()
	})
	if err != nil {
	return false, err
	}
	return exists, nil
	}
	func (s *AnonDBStore) CreateOrUpdateDevice(ctx context.Context, device *Device) error {
	var query string
	// if device limit is reached, only update devices; avoid counting on every update
	if s.deviceLimit > 0 {
	exists, err := s.deviceExists(ctx, device.DeviceID)
	if err != nil {
	return err
	}
	// Existing devices can be updated without counting all devices.
	if exists {
	return s.updateDevice(ctx, device)
	}
	// Only count devices when attempting to create a new device.
	now := time.Now().UTC()
	count, err := s.CountDevices(ctx, now.Add(-anonymousDeviceExpiration), now.Add(time.Minute))
	if err != nil {
	return err
	}
	if count >= s.deviceLimit {
	return ErrDeviceLimitReached
	}

[Copilot]

The default value is undefined, but the TypeScript type in config.ts is number | undefined. For consistency with the backend default of 0 (which means no limit), consider initializing this to 0 instead of undefined to avoid potential undefined checks in consuming code.

Suggested change

	anonymousDeviceLimit = undefined;
	anonymousDeviceLimit = 0;