Sail
A lightweight Rails engine for managing configuration settings, feature flags, and live controls via an admin dashboard.
What is Sail?
Sail is a lightweight Rails engine that adds a setting model to Rails applications for managing configuration settings, feature flags, and live controls. It allows developers to change settings like enabling/disabling features or tuning parameters while the app is running, without needing to redeploy. This solves the problem of static configurations by providing a dynamic, database-backed system for real-time adjustments.
Rails developers and teams who need to manage feature flags, A/B testing, performance tuning, or other live configuration changes in their applications. It's particularly useful for DevOps engineers and product teams experimenting with features in production.
Developers choose Sail for its simplicity, seamless Rails integration, and real-time configuration capabilities without complex infrastructure. Its built-in admin dashboard, relevancy scoring, and support for multiple data types make it a practical alternative to heavier feature flag services.
Overview
Sail is a lightweight Rails engine that brings an admin panel for managing configuration settings on a live Rails app
Use Cases
Best For
- Managing feature flags and A/B testing in Rails applications
- Tuning job parameters or performance settings without redeploys
- Running live experiments to optimize application behavior
- Centralizing configuration management for Rails microservices
- Providing an admin interface for non-technical team members to toggle features
- Switching between configuration profiles for different environments or user segments
Not Ideal For
- Applications not built on Ruby on Rails, as it's a Rails-specific engine with no support for other frameworks
- Teams needing advanced feature flag analytics like user segmentation, percentage rollouts, or real-time impact dashboards
- High-traffic systems where database latency for configuration reads could become a performance bottleneck
- Projects requiring distributed or multi-region configuration management with eventual consistency guarantees
Pros & Cons
Pros
As a Rails engine, Sail installs easily with generators and mounts directly into routes, requiring minimal configuration for quick setup, as shown in the installation steps.
Settings can be changed in real-time via the database-backed system, enabling feature toggles and parameter tuning without redeployment, highlighted by the live dashboard demo.
Includes a responsive interface with search, filtering, and auto-submit features, reducing the need for custom UI development for configuration management.
Calculates usage-based scores for settings to indicate criticality, a unique feature that helps prioritize changes based on invocation frequency.
Supports various data types like boolean, string, and throttle with automatic casting, allowing flexible configuration for different use cases.
Cons
Relies entirely on the application's database for storage, making it a single point of failure and potentially impacting performance with frequent reads, despite caching.
Lacks sophisticated capabilities like user-level targeting or complex rollout strategies, making it unsuitable for intricate A/B testing beyond basic throttling.
Dashboard authorization requires a custom lambda function setup, which adds complexity and potential security risks if not implemented correctly.
Compared to dedicated services like LaunchDarkly, Sail has a smaller community and fewer integrations, limiting support for advanced use cases.
Frequently Asked Questions
Related Projects
dotenvA Ruby gem to load environment variables from `.env`.
FigaroSimple Rails app configuration
ConfigEasiest way to add multi-environment yaml settings to Rails, Sinatra, Padrino and other Ruby projects.
AnywayConfigConfiguration library for Ruby gems and applications
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