Configuration Feature Flags

Feature Flags

Feature flags enable dynamic activation/deactivation of functional features without code deployment.

Concept

Feature flags are cross-context switches that:

• Are centrally defined in rsgo.features.json
• Are passed as environment variables to all containers
• Are evaluated at runtime by services
• Can be changed without redeployment

Definition

In rsgo.features.json

{
  "newColorTheme": true,
  "discussionV2": false,
  "memoRichEditor": true,
  "advancedSearch": true,
  "betaFeatures": false
}

As Environment Variables

This configuration is passed to containers as:

RSGO_FEATURE_newColorTheme=true
RSGO_FEATURE_discussionV2=false
RSGO_FEATURE_memoRichEditor=true
RSGO_FEATURE_advancedSearch=true
RSGO_FEATURE_betaFeatures=false

Usage in Code

Backend (C#)

public class ProjectService
{
    private readonly IConfiguration _config;

    public ProjectService(IConfiguration config)
    {
        _config = config;
    }

    public async Task<Project> GetProjectAsync(string id)
    {
        var project = await _repository.GetAsync(id);

        // Check feature flag
        if (_config.GetValue<bool>("RSGO_FEATURE_advancedSearch"))
        {
            project.SearchMetadata = await _searchService.GetMetadataAsync(id);
        }

        return project;
    }
}

Frontend (TypeScript/React)

// Load feature flags from backend
const features = await api.getFeatureFlags();

// Conditionally render component
{features.newColorTheme && <NewThemeComponent />}
{!features.newColorTheme && <LegacyThemeComponent />}

Manifest Integration

Feature flags can have default values in the manifest:

{
  "manifestVersion": "1.0.0",
  "stackVersion": "4.3.0",
  "features": {
    "newColorTheme": {
      "default": true,
      "description": "New UI theme with improved UX"
    },
    "discussionV2": {
      "default": false,
      "description": "New discussion API (Beta)"
    }
  }
}

These defaults are applied to rsgo.features.json during deployment but can be overridden by the admin later.

Admin UI

The admin UI provides a management page for feature flags:

Overview Page

Feature	Active	Description	Action
newColorTheme	Yes	New UI theme	Toggle
discussionV2	No	New discussion API (Beta)	Toggle
memoRichEditor	Yes	Rich text editor for memos	Toggle
advancedSearch	Yes	Advanced search features	Toggle

Toggle Action

POST /api/v1/features/newColorTheme/toggle

Response:

{
  "feature": "newColorTheme",
  "enabled": false,
  "updatedAt": "2025-11-17T10:30:00Z"
}

API Endpoints

Get Feature Flags

GET /api/v1/features

Response:

{
  "newColorTheme": true,
  "discussionV2": false,
  "memoRichEditor": true
}

Set Feature Flag

PUT /api/v1/features/discussionV2
Content-Type: application/json

{
  "enabled": true
}

Delete Feature Flag

DELETE /api/v1/features/oldFeature

Best Practices

1. Clear Naming

Good: newColorTheme
Good: discussionV2
Bad: feature1
Bad: temp

2. Documentation

Always provide a description in the manifest:

"features": {
  "newFeature": {
    "default": false,
    "description": "What does this feature do?"
  }
}

3. Cleanup

Regularly remove old/unused feature flags.

4. Testing

Consider feature flags in tests:

[Theory]
[InlineData(true)]
[InlineData(false)]
public async Task TestWithFeatureFlag(bool featureEnabled)
{
    // Test both scenarios
}

5. Monitoring

Log feature flag usage:

_logger.LogInformation(
    "Feature {Feature} is {Status}",
    "discussionV2",
    isEnabled ? "enabled" : "disabled"
);

Use Cases

1. Gradual Rollouts

Deploy new feature initially disabled, enable later.

2. A/B Testing

Test different implementations in parallel.

3. Kill Switch

Quickly disable feature in case of problems without rollback.

4. Customer-side Customization

Customers can enable features as needed.

5. Beta Features

Experimental features for early adopters.

Limitations

• No granular control: Feature flags are global, not per user/role
• No percentage rollout: Either on or off, not 50% of users
• No time control: No automatic activation at specific times

These features are planned for future versions.

Next Steps

• Configuration Overview
• Config Files
• Manifest Specification