rating service

.babelrc

@@ -0,0 +1,14 @@
+{
+  "plugins": [
+    "source-map-support",
+    "transform-runtime"
+  ],
+  "presets": [
+    [
+      "env", { 
+        "node": "8.10" 
+      }
+    ],
+    "stage-3"
+  ]
+}

.eslintrc.json

@@ -0,0 +1,30 @@
+{
+  "parser": "babel-eslint",
+  "extends": "airbnb-base",
+  "root": true,
+  "env": {
+    "node": true,
+    "mocha": true
+  },
+  "rules": {
+    "import/no-extraneous-dependencies": [
+      "error",
+      {
+        "devDependencies": true
+      }
+    ],
+    "arrow-parens": 0,
+    "import/imports-first": 0,
+    "global-require": 0,
+    "id-length": 0,
+    "new-cap": 0,
+    "func-names": 0,
+    "no-param-reassign": 0,
+    "generator-star-spacing": 0,
+    "require-yield": 0,
+    "import/prefer-default-export": 0,
+    "no-console": 0,
+    "function-paren-newline": 0,
+    "prefer-destructuring": 0
+  }
+}

.gitignore

@@ -0,0 +1,21 @@
+# package directories
+node_modules
+
+# Serverless directories
+.serverless
+# Coverage directory used by tools like istanbul
+/coverage
+
+#OS STUFF
+.DS_Store
+.tmp
+
+# Logs
+logs
+*.log
+npm-debug.log
+
+#IDE related
+.idea/
+/.webpack/
+/.nyc_output/

.npmignore

@@ -0,0 +1,40 @@
+# Logs
+logs
+*.log
+npm-debug.log
+
+# Runtime data
+pids
+*.pid
+*.seed
+dist
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+.nyc_output
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (http://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directory
+# https://www.npmjs.org/doc/misc/npm-faq.html#should-i-check-my-node_modules-folder-into-git
+node_modules
+
+# useless config files
+.gitignore
+.npmignore
+.babelrc
+.eslintrc.json
+
+# Source and test folders
+src
+test

README.md

@@ -0,0 +1,220 @@
+# Rating Service
+
+This project has been developed as a serverless microservice based on Serverless framework, AWS lambda, API Gateway and the database used is DynamoDB.
+Project will be deployed to AWS `us-east-1` region as defined in `serverless.env.yml` and can be changed through environment files
+based on the environment. Ex:  `serverless.env.yml.dev` is for development environment.
+
+Core of the project is `serverless.yml` file and it is where all the AWS resources, IAM permissions and environment variables
+have been defined.
+
+Ex: Dynamo DB table and index creation, IAM policy for lambda to access resources
+
+**Reasons Behind Choosing the following tech stack.**
+1. Microservice - Well focused small service which provides better maintainability, testability and deployability, 
+2. Serverless - Zero administration, auto scalling, Pay-per-use
+3. DynamoDb - High performing, low latency fully managed NOSQL DB database which seamlessly scalable (serverless). Well fit 
+for AWS labmbda functions 
+
+**Assumptions**: 
+1. Sample-size - It won't return anything if there is no sufficient number of total ratings. Limit has been defined in 
+`src/constant/index.js` and it has been set to 20 currently.
+
+2. Outliers - I assumed that there will be a machine learning model in order to detect outliers and remove / disable from the DB
+
+## Prerequisites
+
+Please follow following steps in order to get the project up and running.
+
+1. Install node.js version 8.10 (AWS Lambda latest supported version)
+
+       nvm install 8.10
+
+2. Register and install Serverless framework globally
+
+       npm install -g serverless
+
+   https://serverless.com/framework/docs/providers/aws/guide/quick-start/
+
+4. Install Dependencies
+
+       npm install
+      
+5. Set up an AWS account to generate credentials for Serverless to access resources
+
+   https://www.youtube.com/watch?v=HSd9uYj2LJA
+   https://serverless.com/framework/docs/providers/aws/guide/credentials/
+
+6. Configure Serverless to use AWS
+
+       serverless config credentials --provider aws --key AKIAIOSFODNN7EXAMPLE --secret wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY
+
+   Keys will be stored in `~/.aws/credentials` in your machine
+
+7. Install AWS CLI
+
+       pip install awscli --upgrade --user
+
+   https://docs.aws.amazon.com/cli/latest/userguide/installing.html
+
+## Development
+
+##### Test End-points Locally
+
+In order to test and debug end-points on your local machine, run the following command on your terminal from the 
+project directory and get URLs as displayed.
+
+    sls offline start
+
+##### Run Lint
+
+    npm run lint
+
+##### Run Spec Tests
+
+    npm run test
+
+**NOTE**: Keep below command running while you change any test, code as it will watch for 
+any change and tests will be run automatically once you hit ctrl+s
+
+    npm run test:watch
+
+##### Run Test Coverage
+
+    npm run coverage
+
+##### Run Integration Tests - Offline
+
+**NOTE**: When running integration tests on your local machine, keep running `serverless offline start` in one tab, and run the following command
+in another one,
+
+    npm run test:integration:offline
+
+##### How To Write Integration Tests
+
+https://scotch.io/tutorials/write-api-tests-with-postman-and-newman
+https://www.getpostman.com/docs/v6/postman/collection_runs/command_line_integration_with_newman
+
+## Deployment
+
+In order to deploy everything to your staging environment in AWS run following command on your terminal from the
+project directory. Once deployment finished it will output all the endpoint URLs on the terminal.
+
+    serverless deploy -v
+
+Note** : Use this method when you have updated your Function, Event or Resource configuration in serverless.yml 
+and you want to deploy that change (or multiple changes at the same time) to AWS.
+
+If you want to deploy only code changes related to a function, use below command, which is faster as it does not touch AWS CloudFormation Stack.
+
+    serverless deploy function --function FunctionName
+
+Fetch logs of a specific function
+
+    serverless logs -f FunctionName -t (optionally tail the logs)
+
+
+## Endpoints
+
+| Method                                       |Description                              |
+|----------------------------------------------|-----------------------------------------|
+| POST /rating                                 | Create rating                           |
+| GET /rating/content/{contentId}              | Get rating by content                   |
+
+#### Common Headers
+
+All the requests should contain following headers.
+
+| Key                | Value                                                               |               
+|--------------------|---------------------------------------------------------------------|
+|Content-Type        | application/json                                            |                                              
+|Accept              | application/json                                            |                                                                
+
+#### Common Errors
+
+| Status code  | Value                                            |               
+|--------------|--------------------------------------------------|
+|400           | Bad Request                                      |                                             
+|403           | Forbidden (incorrect stage, incorrect api key)   | 
+|422           | Unprocessable Entity (validation errors )        |                                            
+|500           | Internal server error                            | 
+
+
+#### 1. Create Rating
+A user can't rate the same content more than once,
+
+#### POST {url}/rating
+
+##### Request
+
+```
+   {
+       "userId": 808,
+       "contentId": 562135,
+       "rating": 4
+   }
+```
+
+##### Response
+
+| Status code  | Value                                                               |               
+|--------------|------------------------------|
+|201           | Created                      | 
+
+```
+   {
+       "userId": 808,
+       "contentId": 562135,
+       "rating": 4
+   }
+```
+
+##### Error Response
+
+ ```{
+        "errors": [
+            {
+                "status": "400",
+                "title": "Bad Request",
+                "detail": "User has already voted for this content"
+            }
+        ]
+    }   
+ ```
+
+#### 2. Get Rating By Content
+
+#### GET {url}/rating/content/{contentId}
+
+##### Response
+
+| Status code  | Value                                                               |               
+|--------------|------------------------------|
+|200           | OK                           | 
+
+```
+  {
+      "contentId": "562135",
+      "averageRating": 3.9,
+      "totalRatingCount": 38,
+      "ratingDetails": {
+          "1": 3,
+          "2": 2,
+          "3": 5,
+          "4": 13,
+          "5": 15
+      }
+  }
+```
+
+##### Error Response
+
+ ```{
+        "errors": [
+            {
+                "status": "400",
+                "title": "Bad Request",
+                "detail": "Insufficient total number of ratings to calculate the average"
+            }
+        ]
+    }   
+ ```