Testing with FastAPI Endpoints
Lab Environment
This lab tests a Kong API Gateway deployment using a FastAPI endpoint. To simplify, both the containerized Kong API Gateway and the FastAPI endpoint are installed locally on a Windows 10 machine. A Docker Compose file is used to deploy Kong, along with other applications like Prometheus, Zipkin, the ELK Stack, and more.
To setup a containerized Kong, please see Containerized Kong and Other Applications.
Make sure that you have installed Docker Desktop.
Simply installing Docker in WSL2 without Docker Desktop may introduce some issue when configuring the communication between the containerized Kong API Gateway and the FastAPI application that is installed on the local host.
Pre-requisites
Setup the API Endpoint
The source code for the FastAPI application can be found here: test-fastapi-simple-app
git clone https://github.com/joseeden/test-fastapi-simple-app.git
cd test-fastapi-simple-app.
pip install -r requirements.txt
python main.py
Output:
INFO: Uvicorn running on http://localhost:5000 (Press CTRL+C to quit)
INFO: Started reloader process [5367] using StatReload
INFO: Started server process [5370]
INFO: Waiting for application startup.
INFO: Application startup complete
Open a web browser and navigate to the endpoint:
http://localhost:5000/healthy
It should return:
Checking the docs:
http://localhost:5000/docs
Back in the terminal, you should see the logs:
INFO: 127.0.0.1:57982 - "GET /healthy HTTP/1.1" 200 OK
INFO: 127.0.0.1:45662 - "GET /docs HTTP/1.1" 200 OK
INFO: 127.0.0.1:39750 - "GET /openapi.json HTTP/1.1" 200 OK
Testing with Postman
Open Postman and create a new workspace by clicking the My Workspaces and select New. Enter "Api Testing" as the name of the workspace and click Create Workspace.
Click + New Collection and add "Kong" as collection name. Click Create.
Click Add requests and then enter:
In the request field, enter the endpoint URL and hit Send. It should return "healthy" in the output body.
http://localhost:5000/healthy
Configure Gateway Service
Go to Kong Manager > Gateway Services > New Gateway Service.
Enter the Name and then choose Protocol, Host, Port and Path. Enter the details below:
| Field | Value |
|---|---|
| Name | fastapi-service |
| Protocol | http |
| Host | host.docker.internal |
| Path | /healthy |
| Port | 5000 |
The new service should now appear in the Gateway Services list.
Configure Route
Go to Kong Manager > Routes > New Route
| Field | Value |
|---|---|
| Name | fastapi-route |
| Service | Select fastapi-service from dropdown |
For HTTP/HTTPs Routing Rules, enter the following paths:
/kong/healthy/kong-test/healthy
For Methods, toggle:
GET
Click Save.
Test New Service via Postman
Open Postman and add a new request. Click Send. It should return a healthy status.
Similarly, it should return healthy for the second path.
To save the request, click the Save button and enter the name "Testing FastAPI via Kong".
Troubleshooting
If the request is timing out:
{
"message": "The upstream server is timing out",
"request_id": "f787c81401190c7d156fea21e3c9ef5b"
}
Check the service from the CLI:
curl http://localhost:8001/services | jq
Output:
{
"data": [
{
"read_timeout": 60000,
"tls_verify": null,
"tls_verify_depth": null,
"id": "5f8cb8d1-18ca-49cf-8c79-b23593e648d9",
"protocol": "http",
"tags": null,
"retries": 5,
"path": "/healthy",
"port": 5000,
"enabled": true,
"client_certificate": null,
"ca_certificates": null,
"name": "fastapi-service",
"host": "host.docker.internal",
"created_at": 1733107301,
"updated_at": 1733109379,
"connect_timeout": 60000,
"write_timeout": 60000
}
],
"next": null
}
Similarly, check the routes:
curl http://localhost:8001/routes | jq
Output:
{
"data": [
{
"paths": [
"/kong/healthy",
"/kong-test/healthy"
],
"request_buffering": true,
"sources": null,
"snis": null,
"protocols": [
"http",
"https"
],
"destinations": null,
"hosts": null,
"methods": [
"GET"
],
"regex_priority": 0,
"response_buffering": true,
"created_at": 1733107937,
"path_handling": "v0",
"headers": null,
"strip_path": true,
"name": "fastapi-route",
"https_redirect_status_code": 426,
"preserve_host": false,
"updated_at": 1733107937,
"service": {
"id": "5f8cb8d1-18ca-49cf-8c79-b23593e648d9"
},
"id": "08baf234-06fb-4f32-9e8a-0f30fd0f0ef1",
"tags": []
}
],
"next": null
}
Test if Kong can reach the FastAPI service:
curl http://host.docker.internal:5000/healthy
If this fails, Kong cannot access your FastAPI app. Consider using localhost with port binding or checking your Docker network settings.
curl: (28) Failed to connect to host.docker.internal port 5000: Connection timed out
Check the container logs for Kong. Find the container first:
docker ps -a --format "table {{.ID}}\t{{.Image}}\t{{.Status}}\t{{.Names}}"
In my case, the container name is kong-1. Check the logs:
docker logs kong-1
Output:
2024/12/02 03:22:47 [error] 1370#0: *6954 upstream timed out (110: Connection timed out) while connecting to upstream, client: 172.1.1.1, server: kong, request: "GET /kong/healthy HTTP/1.1", upstream: "http://192.168.255.22:5000/healthy", host: "127.0.0.1:8000", request_id: "f787c81401190c7d156fea21e3c9ef5b"
2024/12/02 03:23:47 [error] 1370#0: *6954 upstream timed out (110: Connection timed out) while connecting to upstream, client: 172.1.1.1, server: kong, request: "GET /kong/healthy HTTP/1.1", upstream: "http://192.168.255.22:5000/healthy", host: "127.0.0.1:8000", request_id: "f787c81401190c7d156fea21e3c9ef5b"
2024/12/02 03:24:47 [error] 1370#0: *6954 upstream timed out (110: Connection timed out) while connecting to upstream, client: 172.1.1.1, server: kong, request: "GET /kong/healthy HTTP/1.1", upstream: "http://192.168.255.22:5000/healthy", host: "127.0.0.1:8000", request_id: "f787c81401190c7d156fea21e3c9ef5b"
172.1.1.1 - - [02/Dec/2024:03:24:47 +0000] "GET /kong/healthy HTTP/1.1" 504 102
"-" "PostmanRuntime/7.43.0" kong_request_id: "f787c81401190c7d156fea21e3c9ef5b"
172.1.1.1 - - [02/Dec/2024:03:25:37 +0000] "GET /services HTTP/1.1" 200 416 "-"
"curl/7.68.0"
172.1.1.1 - - [02/Dec/2024:03:25:57 +0000] "GET /routes HTTP/1.1" 200 538 "-" "curl/7.68.0"
The log messages indicate that Kong is unable to connect to the upstream FastAPI application, resulting in a 504 Gateway Timeout.
upstream timed out (110: Connection timed out) while connecting to upstream, upstream: "http://192.168.255.22:5000/healthy"