feat: Ruby OF Provider Docs (#821)

Ruby OF Provider Docs

Author: JamieSinn

docs/sdk/server-side-sdks/ruby/ruby-example.mdx

@@ -1,7 +1,7 @@
 ---
 title: Ruby Example Apps
 sidebar_label: Example App
-sidebar_position: 4
+sidebar_position: 5
 description: Try it out for yourself
 sidebar_custom_props: { icon: tabler:devices-code }
 ---

docs/sdk/server-side-sdks/ruby/ruby-openfeature.md

@@ -0,0 +1,124 @@
+---
+title: Ruby OpenFeature Provider
+sidebar_label: OpenFeature
+sidebar_position: 4
+description: How to implement the OpenFeature Provider
+sidebar_custom_props: { icon: material-symbols:toggle-off }
+---
+
+# OpenFeature Provider
+
+OpenFeature is an open standard that provides a vendor-agnostic, community-driven API for feature flagging that works with DevCycle.
+
+DevCycle provides a Ruby implementation of the [OpenFeature](https://openfeature.dev/) Provider interface, if you prefer to use the OpenFeature API.
+
+[![GitHub](https://img.shields.io/github/stars/devcyclehq/ruby-server-sdk.svg?style=social&label=Star&maxAge=2592000)](https://github.com/DevCycleHQ/ruby-server-sdk)
+
+## Usage
+
+### Installation
+[//]: # (wizard-install-start)
+
+Install the OpenFeature Ruby SDK and DevCycle Provider:
+
+```shell
+gem install devcycle-ruby-server-sdk
+```
+
+or 
+
+```shell
+bundler add devcycle-ruby-server-sdk
+```
+
+
+[//]: # (wizard-install-end)
+
+### Getting Started
+[//]: # (wizard-initialize-start)
+
+Initialize the DevCycle SDK and set the DevCycleProvider as the provider for OpenFeature:
+
+```ruby
+require 'open_feature/sdk'
+require 'devcycle-ruby-server-sdk'
+
+dvc_client = DevCycle::Client.new(ENV['DEVCYCLE_SERVER_SDK_KEY'], DevCycle::Options.new)
+OpenFeature::SDK.configure do |config|
+    config.set_provider(dvc_client.open_feature_provider)
+end
+@open_feature_client = OpenFeature::SDK.build_client
+```
+[//]: # (wizard-initialize-end)
+
+### Evaluate a Variable
+Use a Variable value by setting the EvaluationContext, then passing the Variable key and default value to one of the OpenFeature flag evaluation methods.
+
+[//]: # (wizard-evaluate-start)
+
+```ruby
+context = OpenFeature::SDK::EvaluationContext.new(user_id:'user_id')
+flag_value = @open_feature_client.fetch_integer_value(flag_key: 'flag_key', default_value: 1, evaluation_context: context)
+```
+[//]: # (wizard-evaluate-end)
+
+### Required Targeting Key
+
+For the DevCycle SDK to work we require either a `targeting_key` or `user_id` to be set on the OpenFeature context.
+This is used to identify the user as the `user_id` for a `DevCycleUser` in DevCycle.
+
+### Context properties to DevCycleUser
+
+The provider will automatically translate known `DevCycleUser` properties from the OpenFeature context to the `DevCycleUser` object.
+[DevCycleUser Ruby Interface](https://github.com/DevCycleHQ/ruby-server-sdk/blob/main/lib/devcycle-ruby-server-sdk/models/user.rb)
+
+For example all these properties will be set on the `DevCycleUser`:
+
+```ruby
+# Pass context when querying values from the OpenFeature client
+context = OpenFeature::SDK::EvaluationContext.new(
+    user_id: 'user_id',
+    email: 'email',
+    name: 'name',
+    appBuild: 1,
+    appVersion: '1.0.0',
+    randomField: 'value',
+    privateCustomData: { 'secretkey' => 'secretvalue' },
+    customData: { 'key' => 'value' })
+```
+
+Context properties that are not known `DevCycleUser` properties will be automatically
+added to the `customData` property of the `DevCycleUser`.
+
+### Context Limitations
+
+DevCycle only supports flat JSON Object properties used in the Context. Non-flat properties will be ignored.
+
+For example `obj` will be ignored:
+
+```ruby
+context = OpenFeature::SDK::EvaluationContext.new(
+    user_id: 'user_id',
+    obj: { 'secretkey' => 'secretvalue' })
+```
+
+### JSON Flag Limitations
+
+The OpenFeature spec for JSON flags allows for any type of valid JSON value to be set as the flag value.
+
+For example the following are all valid default value types to use with OpenFeature:
+
+```ruby
+# Invalid JSON values for the DevCycle SDK, will return defaults
+open_feature_client.fetch_object_value(flag_key: 'json-variable', default_value: 1.0, evaluation_context: context)
+open_feature_client.fetch_object_value(flag_key: 'json-variable', default_value: false, evaluation_context: context)
+open_feature_client.fetch_object_value(flag_key: 'json-variable', default_value: 'string', evaluation_context: context)
+open_feature_client.fetch_object_value(flag_key: 'json-variable', default_value: nil, evaluation_context: context)
+```
+
+However, these are not valid types for the DevCycle SDK, the DevCycle SDK only supports JSON Objects:
+
+```ruby
+# Valid JSON Object as the default value, will be evaluated by the DevCycle SDK
+@client.fetch_object_value(flag_key: 'json-variable', default_value: { 'key' => 'value' }, evaluation_context: context)
+```