The-ApiGateway-With-IdentityServer

2 very important components for Microservice based architecture:

• i) Authentication/Authorization server
• ii) API Gateway/Ocelot
  are demonated here:
  - Authentication server is used here for generating jwt token. Based on that token, API gateway exposed endpoint can be called.
  - API Gateway exposed endpoints publicly to consume that private endpoints.

Identity Server4:

Identity Server4 is an OpenIDConnect and OAth2.0 framework for ASPNET Core. It provides jwt token for authentication/authorization.

Benifits:

• Centralize authentication logic for all applications (web, mobile, native, services).
• Authentication as Service.
• Access Control for API's using token generation.
• Use as Federated Gateway (external identity providers (google, facebook, Azure Active directory)
• Single Singin/Signout
• Support Dotnet foundation.
• Apachi2 licence

API Gateway:

Take all API calls from clients, then route them to the appropriate microservices with request routing, composition and protocol translation. Typically it handles a request by invoking multiple microservices and aggregate the results. It can translate between Web protocol. It invoke various services like product info and review and combine the results.

Benifits:

• Act as reverse proxy.
• No need to expose real services endpoints publicly.
• Authentication feature
• Response Caching.
• Api call tracking and Bill generation if needed.
• Centralize API management.

Technology used:

• Aspnet Core
• IdentityServer4
• Ocelot API gateway

How to run:

• There are 3 projects in the solution:
• 1. IdentityServer project
• 2. Ocelot project
• 3. TodoApi project

Steps to follow:

• Step 1. You need to run both 3 projects.
• Step 2. Call IdentityServer projects endpoint (https://localhost:4001/connect/token) (using postman)
• Step 3. Using that token call API gateway exposed endpoint(GET https://localhost:6001/api/todo)
• Step 4. You will received the todo list.

Note:

• If you call API gateway exposed endpoints (Ocelot project) without valid token you will get 401 unauthorized error
• If you call directly TodoApi endpoints (TodoApi project) you can get data without any token.
• Scenario: Todo project endpoinsts will be in any private networks and not exposed outside the network. But your Ocelot project(API gateway project) will be exposed publicly (with authentication).
• Hope you understand the real usecase (Please check the POSTMAN screenshot bellow).

Collect Jwt Token:

Single API call (without any parameters) with exposed API gateway endpoints (return array of Todo objects):

Single API call (with parameters) with exposed API gateway endpoints (return String):

Single API call with exposed API gateway endpoints which return and merged data with 2 API call: