🧭 Microservices Gateway with Ocelot and Swagger (.NET 9) This solution demonstrates a simple API Gateway built with Ocelot that routes traffic to two downstream microservices:
AuthService — handles authentication and issues JWT tokens.DataService — exposes example data endpoints.
The gateway also aggregates both services’ Swagger documentation using SwaggerForOcelot , providing a unified API explorer at a single URL.
Component
Purpose
.NET 9 Framework for all services
Ocelot API Gateway / Reverse Proxy
MMLib.SwaggerForOcelot Aggregates Swagger from downstream services
Swashbuckle.AspNetCore Swagger UI for microservices
JWT Bearer Auth Token-based authentication (AuthService)
┌─────────────────────────────┐
│ API Gateway │
│ (Ocelot + SwaggerForOcelot) │
│ Port: 5123 │
└───────┬───────────┬─────────┘
│ │
▼ ▼
┌─────────────────────────────┐ ┌─────────────────────────────┐
│ AuthService │ │ DataService │
│ Issues JWT tokens │ │ Returns product data │
│ Port: 5138 │ │ Port: 5146 │
└─────────────────────────────┘ └─────────────────────────────┘
MicroservicesOcelotDemo/
│
├── ApiGateway/
│ ├── Program.cs
│ ├── ocelot.json
│
├── AuthService/
│ ├── Program.cs
│
├── DataService/
│ ├── Program.cs
│
└── TestClient/
└── Program.cs
git clone https://github.com/YOUR_USERNAME/MicroservicesOcelotDemo.git
cd MicroservicesOcelotDemo 3️⃣ Run Each Service in Separate Terminals # Auth Service (port 5138)cd AuthService
dotnet run --urls http://localhost:5138# Data Service (port 5146)cd DataService
dotnet run --urls http://localhost:5146# API Gateway (port 5123)cd ApiGateway
dotnet run --urls http://localhost:5123🧭 Gateway Routing Summary
Gateway Path
Forwards To
Description
/auth/*http://localhost:5138/*Auth endpoints
/data/*http://localhost:5146/*Data endpoints
/swaggerAggregated docs
SwaggerForOcelot UI
curl -X POST http://localhost:5123/auth/token \
-H " Content-Type: application/json" ' { "username": "demo", "password": "demo" }' curl http://localhost:5123/data/products \
-H " Authorization: Bearer YOUR_JWT_TOKEN" 🧩 Key Configuration Files {
"Routes" : [
{
"UpstreamPathTemplate" : " /auth/{everything}" "UpstreamHttpMethod" : [ " Get" " Post" " Put" " Delete" " Options" "DownstreamPathTemplate" : " /{everything}" "DownstreamScheme" : " http" "DownstreamHostAndPorts" : [ { "Host" : " localhost" "Port" : 5138 } ]
},
{
"UpstreamPathTemplate" : " /data/{everything}" "UpstreamHttpMethod" : [ " Get" " Post" " Put" " Delete" " Options" "DownstreamPathTemplate" : " /{everything}" "DownstreamScheme" : " http" "DownstreamHostAndPorts" : [ { "Host" : " localhost" "Port" : 5146 } ]
}
],
"SwaggerEndPoints" : [
{
"Key" : " auth" "TransformByOcelotConfig" : true ,
"Config" : [
{ "Name" : " Auth Service" "Version" : " v1" "Url" : " http://localhost:5138/swagger/v1/swagger.json" "Key" : " data" "TransformByOcelotConfig" : true ,
"Config" : [
{ "Name" : " Data Service" "Version" : " v1" "Url" : " http://localhost:5146/swagger/v1/swagger.json" "GlobalConfiguration" : { "BaseUrl" : " http://localhost:5123"
The gateway is configured purely as a reverse proxy — no authentication required.
Both microservices have independent Swagger UIs.
The gateway’s Swagger aggregates both under /swagger.
You can later enable JWT validation or rate limiting if needed.
Project
Package
Purpose
ApiGateway
OcelotReverse proxy / API Gateway
ApiGateway
MMLib.SwaggerForOcelot.AspNetCoreAggregates Swagger docs
AuthService
Swashbuckle.AspNetCoreSwagger UI
DataService
Swashbuckle.AspNetCoreSwagger UI
AuthService / DataService
Microsoft.AspNetCore.Authentication.JwtBearerJWT auth
This project is licensed under the MIT License .
Feel free to use, modify, and share.