https://github.com/eiskrenkov/fino
Dynamic settings engine
https://github.com/eiskrenkov/fino
engine rails redis ruby
Last synced: 5 days ago
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Dynamic settings engine
- Host: GitHub
- URL: https://github.com/eiskrenkov/fino
- Owner: eiskrenkov
- License: mit
- Created: 2025-08-28T17:42:25.000Z (about 2 months ago)
- Default Branch: master
- Last Pushed: 2025-09-19T12:12:17.000Z (24 days ago)
- Last Synced: 2025-09-21T04:57:43.861Z (22 days ago)
- Topics: engine, rails, redis, ruby
- Language: HTML
- Homepage: https://fino.iskrenkov.me/fino
- Size: 235 KB
- Stars: 29
- Watchers: 2
- Forks: 0
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Fino
⚠️ Fino in active development phase at wasn't properly battle tested in production just yet. Give us a star and stay tuned for Production test results and new features
Fino is a dynamic settings engine for Ruby and Rails
## Usage
### Define settings via DSL
```ruby
require "fino-redis"
Fino.configure do
adapter do
Fino::Redis::Adapter.new(
Redis.new(**Rails.application.config_for(:redis))
)
end
cache { Fino::Cache::Memory.new(expires_in: 3.seconds) }
settings do
setting :maintenance_mode, :boolean, default: false
setting :api_rate_limit,
:integer,
default: 1000,
description: "Maximum API requests per minute per user to prevent abuse"
section :openai, label: "OpenAI" do
setting :model,
:string,
default: "gpt-5",
description: "OpenAI model"
setting :temperature,
:float,
default: 0.7,
description: "Model temperature"
end
section :feature_toggles, label: "Feature Toggles" do
setting :new_ui, :boolean, default: true
setting :beta_functionality, :boolean, default: false
end
section :my_micro_service, label: "My Micro Service" do
setting :http_read_timeout, :integer, default: 200 # in ms
setting :http_open_timeout, :integer, default: 100 # in ms
end
end
end
```
### Work with settings
```ruby
Fino.value(:model, at: :openai) #=> "gpt-5"
Fino.value(:temperature, at: :openai) #=> 0.7
Fino.values(:model, :temperature, at: :openai) #=> ["gpt-4", 0.7]
Fino.set(model: "gpt-5", at: :openai)
Fino.value(:model, at: :openai) #=> "gpt-5"
```
### Overrides
```ruby
Fino.value(:model, at: :openai) #=> "gpt-5"
Fino.set(model: "gpt-5", at: :openai, overrides: { "qa" => "our_local_model_not_to_pay_to_sam_altman" })
Fino.value(:model, at: :openai) #=> "gpt-5"
Fino.value(:model, at: :openai, for: "qa") #=> "our_local_model_not_to_pay_to_sam_altman"
```
### A/B testing
```ruby
Fino.value(:model, at: :openai) #=> "gpt-5"
# "gpt-5" becomes the control variant value and a 20.0% variant is created with value "gpt-6"
Fino.set(model: "gpt-5", at: :openai, variants: { 20.0 => "gpt-6" })
Fino.setting(:model, at: :openai).experiment.variant(for: "user_1") #=> #
# Picked variant is sticked to the user
Fino.value(:model, at: :openai, for: "user_1") #=> "gpt-6"
Fino.value(:model, at: :openai, for: "user_1") #=> "gpt-6"
Fino.value(:model, at: :openai, for: "user_2") #=> "gpt-5"
```
## Rails integration
Fino comes with a seamless Rails integration which automatically detects when gem is used in Rails context and requires
all necessary facilities on its own
### UI engine
Mount Fino Rails engine in your `config/routes.rb`:
```ruby
Rails.application.routes.draw do
mount Fino::Rails::Engine, at: "/fino"
end
```
### Configuration
```ruby
Rails.application.configure do
config.fino.instrument = true
config.fino.log = true
config.fino.cache_within_request = false
config.fino.preload_before_request = true
end
```
## Performance tweaks
1. In Memory cache
Fino provides in-memory settings caching functionality which will store settings received from adaper in memory for
a very quick access. As this kind of cache is not distributed between machines, but belongs to each process
separately, it's impossible to invalidate all at once, so be aware that setting update application time will depend
on cache TTL you configure
```ruby
Fino.configure do
# ...
cache { Fino::Cache::Memory.new(expires_in: 3.seconds) }
# ...
end
```
2. Request scoped cache
When using Fino in Rails context it's possible to cache settings within request, in current thread storage. This is
safe way to cache settings as it's lifetime is limited, thus it is enabled by default
```ruby
Rails.application.configure do
config.fino.cache_within_request = true
end
```
3. Preloading
In Rails context it is possible to tell Fino to preload multiple settings before processing request in a single
adapter call. Preloading is recommended for requests that use multiple different settings in their logic
```ruby
# Preload all settings
Rails.application.configure do
config.fino.preload_before_request = true
end
# Preload specific subset of settings depending on request
Rails.application.configure do
config.fino.preload_before_request = ->(request) {
case request.path
when "request/using/all/settings"
true
when "request/not/using/settings"
false
when "request/using/specific/settings"
[
:api_rate_limit,
openai: [:model, :temperature]
]
end
}
end
```
## Releasing
`rake release`
## Contributing
1. Fork it
2. Do contribution
6. Create Pull Request into this repo