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defmodule DaProductApp.FeatureFlags do |
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@moduledoc """ |
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Feature flag system for gradual migration and A/B testing. |
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This module provides a centralized way to enable/disable features |
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during development and production deployments, supporting the |
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gradual migration strategy. |
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""" |
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@doc """ |
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Check if a feature flag is enabled. |
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Priority order: |
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1. Environment variables (FEATURE_<FLAG_NAME>=true/false) |
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2. Application config |
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3. Database settings (when implemented) |
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4. Default value |
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""" |
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def enabled?(flag_name, default \\ false) do |
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flag_name |
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|> to_string() |
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|> String.upcase() |
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|> check_feature_flag(default) |
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end |
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@doc """ |
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Enable a feature flag programmatically. |
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Useful for testing and dynamic feature control. |
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""" |
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def enable(flag_name) do |
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Application.put_env(:da_product_app, :feature_flags, |
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Keyword.put(get_feature_flags(), flag_name, true) |
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) |
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end |
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@doc """ |
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Disable a feature flag programmatically. |
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""" |
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def disable(flag_name) do |
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Application.put_env(:da_product_app, :feature_flags, |
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Keyword.put(get_feature_flags(), flag_name, false) |
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) |
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end |
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@doc """ |
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Get all currently configured feature flags. |
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""" |
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def list_flags do |
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get_feature_flags() |
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end |
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# Available feature flags for our gradual migration |
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@available_flags %{ |
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# Data source flags |
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use_database_settings: false, |
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use_database_international_payments: false, |
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use_database_settlements: false, |
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# Performance flags |
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use_redis_caching: false, |
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enable_transaction_type_filtering: true, |
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# Audit and logging flags |
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enable_api_request_logging: true, |
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enable_response_logging: true, |
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enable_log_viewer: false, |
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# Fallback and reliability flags |
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enable_database_fallback: true, |
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enable_file_logging_on_db_failure: true, |
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# UI and monitoring flags |
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show_real_time_metrics: false, |
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enable_advanced_monitoring: false |
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} |
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@doc """ |
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Get default configuration for all available flags. |
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""" |
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def default_flags, do: @available_flags |
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# Private functions |
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defp check_feature_flag(flag_name, default) do |
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# 1. Check environment variable first |
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case System.get_env("FEATURE_#{flag_name}") do |
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"true" -> true |
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"false" -> false |
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nil -> |
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# 2. Check application config |
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case get_feature_flags()[String.to_atom(String.downcase(flag_name))] do |
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nil -> default |
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value -> value |
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end |
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_ -> default |
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end |
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end |
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defp get_feature_flags do |
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Application.get_env(:da_product_app, :feature_flags, []) |
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end |
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end |