Harness CF Ruby Server SDK

Intro
Requirements
Quickstart
Further Reading
Build Instructions

Intro

Harness Feature Flags (FF) is a feature management solution that enables users to change the software’s functionality, without deploying new code. FF uses feature flags to hide code or behaviours without having to ship new versions of the software. A feature flag is like a powerful if statement.

For more information, see https://harness.io/products/feature-flags/
To read more, see https://ngdocs.harness.io/category/vjolt35atg-feature-flags
To sign up, https://app.harness.io/auth/#/signup/

FeatureFlags

Requirements

Ruby 2.7 or newer (ruby --version)

Quickstart

The Feature Flag SDK provides a client that connects to the feature flag service, and fetches the value of feature flags. The following section provides an example of how to install the SDK and initialize it from an application. This quickstart assumes you have followed the instructions to setup a Feature Flag project and have created a flag called harnessappdemodarkmode and created a server API Key.

Install the SDK

Install the ruby SDK using gem

gem install ff-ruby-server-sdk

or by adding the following snippet to your project's Gemfile file:

gem "ff-ruby-server-sdk"

A Simple Example

Here is a complete example that will connect to the feature flag service and report the flag value every 10 seconds until the connection is closed.
Any time a flag is toggled from the feature flag service you will receive the updated value.

require 'ff/ruby/server/sdk/api/config'
require 'ff/ruby/server/sdk/dto/target'
require 'ff/ruby/server/sdk/api/cf_client'
require 'ff/ruby/server/sdk/api/config_builder'

require "logger"
require "securerandom"

$stdout.sync = true
logger = Logger.new $stdout

# API Key
apiKey = ENV['FF_API_KEY'] || 'changeme'

# Flag Name
flagName = ENV['FF_FLAG_NAME'] || 'harnessappdemodarkmode'

# Create a Feature Flag Client and wait for it to initialize
client = CfClient.instance
client.init(apiKey, ConfigBuilder.new.logger(logger).build)
client.wait_for_initialization

# Create a target (different targets can get different results based on rules.  This include a custom attribute 'location')
target = Target.new("RubySDK", identifier="rubysdk", attributes={"location": "emea"})

# Loop forever reporting the state of the flag
loop do
  result = client.bool_variation(flagName, target, false)
  logger.info "Flag variation:  #{result}"
  sleep 10
end

client.close

Running the example

# Install the deps
gem install ff-ruby-server-sdk typhoeus

# Set your API Key
export FF_API_KEY=<your key here>

# Run the example
ruby ./example/getting_started/getting_started.rb

Running with docker

If you don't have the right version of ruby installed locally, or don't want to install the dependencies you can use docker to quickly get started

# Install the package
docker run -v $(pwd):/app -w /app -e FF_API_KEY=$FF_API_KEY ruby:2.7-buster gem install --install-dir ./gems ff-ruby-server-sdk typhoeus

# Run the script
docker run -v $(pwd):/app -w /app -e FF_API_KEY=$FF_API_KEY -e GEM_HOME=/app/gems ruby:2.7-buster ruby ./example/getting_started/getting_started.rb

Additional Reading

Further examples and config options are in the further reading section: