feat(#19): Manage exceptions by default and allow the gem's consumer to manage them by itself

CHANGELOG.md

@@ -4,7 +4,7 @@ All changes to `grape-idempotency` will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [1.0.1] - (Next)
+## [1.1.0] - (Next)
 
 ### Fix
 
@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Feature
 
+* [#20](https://github.com/jcagarcia/grape-idempotency/pull/20): Manage `Redis` exceptions by default and allow the gem's consumer to manage them by itself - [@jcagarcia](https://github.com/jcagarcia).
 * Your contribution here.
 
 ## [1.0.0] - 2023-11-23

README.md

@@ -12,7 +12,8 @@ Topics covered in this README:
 - [Installation](#installation-)
 - [Basic Usage](#basic-usage-)
 - [How it works](#how-it-works-)
-- [Making idempotency key header mandatory](#making-idempotency-key-header-mandatory-)
+  - [Making idempotency key header mandatory](#making-idempotency-key-header-mandatory-)
+  - [Redis Storage Connectivity Issue](#redis-storage-connectivity-issue)
 - [Configuration](#configuration-)
 - [Changelog](#changelog)
 - [Contributing](#contributing)
@@ -81,7 +82,7 @@ Results are only saved if an API endpoint begins its execution. If incoming para
 
 Additionally, this gem automatically appends the `Original-Request` header and the `Idempotency-Key` header to your API's response, enabling you to trace back to the initial request that generated that specific response.
 
-## Making idempotency key header mandatory ⚠️
+### Making idempotency key header mandatory ⚠️
 
 For some endpoints, you want to enforce your consumers to provide idempotency key. So, when wrapping the code inside the `idempotent` method, you can mark it as `required`:
 
@@ -113,6 +114,37 @@ If the Idempotency-Key request header is missing for a idempotent operation requ
 
 If you want to change the error message returned in this scenario, check [How to configure idempotency key missing error message](#mandatory_header_response) section.
 
+### Redis Storage Connectivity Issue
+
+By default, `Redis` exceptions are not handled by the `grape-idempotency` gem.
+
+Therefore, if an exception arises while attempting to read, write or delete data from the `Redis` storage, the gem will re-raise the identical exception to your application. Thus, you will be responsible for handling it within your own code, such as:
+
+```ruby
+require 'grape'
+require 'grape-idempotency'
+
+class API < Grape::API
+    post '/payments' do
+      begin
+        idempotent do
+          status 201
+          Payment.create!({
+            amount: params[:amount]
+          })
+        end
+      rescue Redis::BaseError => e
+        error!("Redis error! Idempotency is very important here and we cannot continue.", 500)
+      end
+    end
+  end
+end
+```
+
+If you want to avoid this functionality, and you want the gem handles the potential `Redis` exceptions, you have the option to configure the gem for handling these `Redis` exceptions. Please refer to the [manage_redis_exceptions](#manage_redis_exceptions) configuration property.
+
+🚨 WARNING: If a `Redis` exception appears AFTER performing the wrapped code, nothing will be re-raised. The process will continue working and the response will be returned to the consumer of your API. However, a `409 Conflict` response can be returned to your consumer if it retried the same call with the same idempotency key. This is because the gem was not able to associate the response of the original request to the original idempotency key because those connectivity issues.
+
 ## Configuration 🪚
 
 In addition to the storage aspect, you have the option to supply additional configuration details to tailor the gem to the specific requirements of your project.
@@ -195,6 +227,21 @@ I, [2023-11-23T22:41:39.148523 #1]  DEBUG -- : [my-own-prefix] Request has been
 I, [2023-11-23T22:41:39.148537 #1]  DEBUG -- : [my-own-prefix] Returning the response from the original request.
 ```
 
+### manage_redis_exceptions
+
+By default, the `grape-idempotency` gem is configured to re-raise `Redis` exceptions.
+
+If you want to delegate the `Redis` exception management into the gem, you can configure it using the `manage_redis_exceptions` configuration property.
+
+```ruby
+Grape::Idempotency.configure do |c|
+  c.storage = @storage
+  c.manage_redis_exceptions = true
+end
+```
+
+However, this approach carries a certain level of risk. In the case that `Redis` experiences an outage, the idempotent functionality will be lost, the endpoint will behave as no idempotent, and this issue may go unnoticed.
+
 ### conflict_error_response
 
 When providing a `Idempotency-Key: <key>` header, this gem compares incoming parameters to those of the original request (if exists) and returns a `409 - Conflict` status code if they don't match, preventing accidental misuse. The response body returned by the gem looks like:

grape-idempotency.gemspec

@@ -22,7 +22,8 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = '>= 2.6'
 
-  spec.add_runtime_dependency 'grape', '~> 1'
+  spec.add_runtime_dependency 'grape', '>= 1'
+  spec.add_runtime_dependency 'redis', '>= 4'
 
   spec.add_development_dependency 'bundler'
   spec.add_development_dependency 'rspec'

lib/grape/idempotency.rb

@@ -1,4 +1,5 @@
 require 'grape'
+require 'redis'
 require 'logger'
 require 'securerandom'
 require 'grape/idempotency/version'
@@ -33,21 +34,21 @@ def idempotent(grape, required: false, &block)
         grape.error!(configuration.mandatory_header_response, 400) if required && !idempotency_key
         return block.call if !idempotency_key
 
-        cached_request = get_from_cache(idempotency_key)
-        log(:debug, "Request has been found for the provided idempotency key => #{cached_request}") if cached_request
-        if cached_request && (cached_request["params"] != grape.request.params || cached_request["path"] != grape.request.path)
-          log(:debug, "Request has conflicts. Same params? => #{cached_request["params"] != grape.request.params}. Same path? => #{cached_request["path"] != grape.request.path}")
+        stored_request = get_from_storage(idempotency_key)
+        log(:debug, "Request has been found for the provided idempotency key => #{stored_request}") if stored_request
+        if stored_request && (stored_request["params"] != grape.request.params || stored_request["path"] != grape.request.path)
+          log(:debug, "Request has conflicts. Same params? => #{stored_request["params"] != grape.request.params}. Same path? => #{stored_request["path"] != grape.request.path}")
           log(:debug, "Returning conflict error response.")
           grape.error!(configuration.conflict_error_response, 422)
-        elsif cached_request && cached_request["processing"] == true
+        elsif stored_request && stored_request["processing"] == true
           log(:debug, "Returning processing error response.")
           grape.error!(configuration.processing_response, 409)
-        elsif cached_request
+        elsif stored_request
           log(:debug, "Returning the response from the original request.")
-          grape.status cached_request["status"]
-          grape.header(ORIGINAL_REQUEST_HEADER, cached_request["original_request"])
+          grape.status stored_request["status"]
+          grape.header(ORIGINAL_REQUEST_HEADER, stored_request["original_request"])
           grape.header(configuration.idempotency_key_header, idempotency_key)
-          return cached_request["response"]
+          return stored_request["response"]
         end
 
         log(:debug, "Previous request information has NOT been found for the provided idempotency key.")
@@ -76,26 +77,32 @@ def idempotent(grape, required: false, &block)
 
         grape.header(ORIGINAL_REQUEST_HEADER, original_request_id)
         grape.body response
+      rescue Redis::BaseError => e
+        raise
       rescue => e
         log(:debug, "An unexpected error was raised when performing the block.")
-        if !cached_request && !response
+        if !stored_request && !response
           validate_config!
           log(:debug, "Storing error response.")
           original_request_id = get_request_id(grape.request.headers)
           stored_key = store_error_request(idempotency_key, grape.request.path, grape.request.params, grape.status, original_request_id, e)
-          log(:debug, "Error response stored.")
-          grape.header(ORIGINAL_REQUEST_HEADER, original_request_id)
-          grape.header(configuration.idempotency_key_header, stored_key)
+          if stored_key
+            log(:debug, "Error response stored.")
+            grape.header(ORIGINAL_REQUEST_HEADER, original_request_id)
+            grape.header(configuration.idempotency_key_header, stored_key)
+          end
         end
         log(:debug, "Re-raising the error.")
         raise
       ensure
-        if !cached_request && response
+        if !stored_request && response
           validate_config!
           log(:debug, "Storing response.")
           stored_key = store_request_response(idempotency_key, grape.request.path, grape.request.params, grape.status, original_request_id, response)
-          log(:debug, "Response stored.")
-          grape.header(configuration.idempotency_key_header, stored_key)
+          if stored_key
+            log(:debug, "Response stored.")
+            grape.header(configuration.idempotency_key_header, stored_key)
+          end
         end
       end
 
@@ -113,6 +120,9 @@ def update_error_with_rescue_from_result(error, status, response)
 
         store_request_response(idempotency_key, path, params, status, original_request_id, response)
         storage.del(stored_error[:error_key])
+      rescue Redis::BaseError => e
+        log(:error, "Storage error => #{e.message} - #{e}")
+        nil
       end
 
       private
@@ -122,7 +132,10 @@ def validate_config!
       end
 
       def valid_storage?
-        configuration.storage && configuration.storage.respond_to?(:set)
+        configuration.storage &&
+        configuration.storage.respond_to?(:get) &&
+        configuration.storage.respond_to?(:set) &&
+        configuration.storage.respond_to?(:del)
       end
 
       def get_idempotency_key(headers)
@@ -141,11 +154,15 @@ def get_request_id(headers)
         request_id || "req_#{SecureRandom.hex}"
       end
 
-      def get_from_cache(idempotency_key)
+      def get_from_storage(idempotency_key)
         value = storage.get(key(idempotency_key))
         return unless value
 
         JSON.parse(value)
+      rescue Redis::BaseError => e
+        log(:error, "Storage error => #{e.message} - #{e}")
+        return if configuration.manage_redis_exceptions
+        raise
       end
 
       def store_processing_request(idempotency_key, path, params, request_id)
@@ -157,6 +174,9 @@ def store_processing_request(idempotency_key, path, params, request_id)
         }
 
         storage.set(key(idempotency_key), body.to_json, ex: configuration.expires_in, nx: true)
+      rescue Redis::BaseError => e
+        return true if configuration.manage_redis_exceptions
+        raise
       end
 
       def store_request_response(idempotency_key, path, params, status, request_id, response)
@@ -170,6 +190,9 @@ def store_request_response(idempotency_key, path, params, status, request_id, re
 
         storage.set(key(idempotency_key), body.to_json, ex: configuration.expires_in, nx: false)
 
+        idempotency_key
+      rescue Redis::BaseError => e
+        log(:error, "Storage error => #{e.message} - #{e}")
         idempotency_key
       end
 
@@ -187,6 +210,9 @@ def store_error_request(idempotency_key, path, params, status, request_id, error
 
         storage.set(error_key(idempotency_key), body, ex: 30, nx: false)
 
+        idempotency_key
+      rescue Redis::BaseError => e
+        log(:error, "Storage error => #{e.message} - #{e}")
         idempotency_key
       end
 
@@ -207,6 +233,9 @@ def get_error_request_for(error)
             }
           end
         end.first
+      rescue Redis::BaseError => e
+        log(:error, "Storage error => #{e.message} - #{e}")
+        nil
       end
 
       def is_an_error?(response)
@@ -252,7 +281,8 @@ def configuration
 
     class Configuration
       attr_accessor :storage, :logger, :logger_level, :logger_prefix, :expires_in, :idempotency_key_header,
-        :request_id_header, :conflict_error_response, :processing_response, :mandatory_header_response
+        :request_id_header, :conflict_error_response, :processing_response, :mandatory_header_response,
+        :manage_redis_exceptions
 
       class Error < StandardError; end
 
@@ -264,6 +294,7 @@ def initialize
         @expires_in = 216_000
         @idempotency_key_header = "idempotency-key"
         @request_id_header = "x-request-id"
+        @manage_redis_exceptions = false
         @conflict_error_response = {
           "title" => "Idempotency-Key is already used",
           "detail" => "This operation is idempotent and it requires correct usage of Idempotency Key. Idempotency Key MUST not be reused across different payloads of this operation."

lib/grape/idempotency/version.rb

@@ -2,6 +2,6 @@
 
 module Grape
   module Idempotency
-    VERSION = '1.0.1'
+    VERSION = '1.1.0'
   end
 end