FeatureFlag

FeatureFlag is project to abstract the communication with Launch Darkly SDK.

Installation

Add git repository feature_flag in your mix.exs:

defp deps do
  [
    ...,
    # To use newest version
    {:feature_flag, git: "https://github.com/solfacil/feature-flag.git", branch: "main"}
    # To use a specific git tag version
    {:feature_flag, git: "https://github.com/solfacil/feature-flag.git", tag: "x.x.x"}
  ]
end

For details about git repository in deps, read Git options.

Usage

A client instance must be started for feature flag evaluation to work. We recommend use FeatureFlag.Server to start a client instance on application startup and then feel free to use FeatureFlag.check/3 function to get feature flag value.

Below is a suggestion how to use the lib

Use config/<env>.exs to set the Launch Darkly secret key.

config :my_app, :feature_flag, secret_key: "ld-secret-key"

Add FeatureFlag.Server to your MyApp.Application to start a client instance.

defmodule MyApp.Application do
  @moduledoc false

  use Application

  def start(_type, _args) do
    children = [
      {FeatureFlag.Server, [secret_key: secret_key()]}
    ]

    opts = [strategy: :one_for_one, name: MyApp.Supervisor]
    Supervisor.start_link(children, opts)
  end

  defp secret_key, do: Application.get_env(:my_app, :feature_flag)[:secret_key]
end

If no :secret_key option are given, an error will be thrown.

Now you are ready to go. Use FeatureFlag.check/3 to evaluate given flag value for given user.

iex> user = %FeatureFlag.User{key: "123abc", name: "John", email: "[email protected]"}
iex> FeatureFlag.check("admin-report", user)
true