# Python REST API Test Application


![Python REST API application](/images/python-rest-api-test-application/Screenshot-2020-11-20-at-23.08.36.png)

When you work in platform engineering focused on infrastructure, you sometimes need to create prototypes specifically built for platform testing purposes. I needed a backend that could simulate real API behavior without coupling to any actual business logic — something I could abuse freely.

Two goals:
- Function as a REST API
- Run in Kubernetes

## Running Locally

Build the image and run it:

```
docker build --tag pytbak:0.1 .
docker run -t -p 5000:5000 pytbak:0.1
```

Access the application at `localhost:5000/api/`

## Kubernetes Deployment

From the main folder, apply the configurations:

```
kubectl apply -f kubernetes/
```

Verify it's running:

```
$ kubectl get pods -n pytbak
NAME                             READY   STATUS    RESTARTS   AGE
pytbak-stable-5dfb4fbfd4-n64kx   1/1     Running   0          40m
```

## Ingress Configuration

You need to change the host in the Ingress file to match your environment:

```yaml
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: pytbak-ingress
  namespace: pytbak
  annotations:
    ingress.kubernetes.io/proxy-connect-timeout: "10"
    ingress.kubernetes.io/proxy-read-timeout: "30"
    ingress.kubernetes.io/proxy-send-timeout: "30"
spec:
  rules:
  - host: pytbak.ing.h4x0r3d.lan
    http:
      paths:
      - path: /
        backend:
          serviceName: pytbak-svc
          servicePort: 5000
```

The example uses `pytbak.ing.h4x0r3d.lan` — that's my homelab ingress DNS.

## DNS Strategy

My home DNS is `h4x0r3d.lan` with `*.ing.h4x0r3d.lan` as a wildcard A record pointing to the Kubernetes ingress. This means I don't need to add DNS entries per service — whatever namespace I create automatically becomes accessible at `<namespace>.ing.h4x0r3d.lan`. Create a namespace called "pippo" and it's immediately at `pippo.ing.h4x0r3d.lan`.

Simple, and it eliminates the DNS management overhead entirely.

## API Endpoints

The application responds on `/api/` with an HTML interface documenting available methods:

| HTTP Method | URI | Action |
|-------------|-----|--------|
| GET | /api/get/context | Retrieve list of contexts |
| GET | /api/get/context/[context_id] | Retrieve a specific context |
| POST | /api/post/context | Create a new context |
| PUT | /api/put/context/[context_id] | Update an existing context |
| DELETE | /api/delete/context/[context_id] | Delete a context |

## Examples

**GET all contexts:**

```
$ curl -i http://pytbak.ing.h4x0r3d.lan/api/get/context
HTTP/1.1 200 OK
Server: openresty/1.15.8.1
Content-Type: application/json

{
  "context": [
    {
      "description": "RHEL 6 based",
      "done": false,
      "title": "Cento 6",
      "uri": "http://pytbak.ing.h4x0r3d.lan/api/get/context/1"
    },
    {
      "description": "RHEL 7 based",
      "done": false,
      "title": "Centos 7",
      "uri": "http://pytbak.ing.h4x0r3d.lan/api/get/context/2"
    },
    {
      "description": "RHEL 8 based",
      "done": false,
      "title": "Centos 8",
      "uri": "http://pytbak.ing.h4x0r3d.lan/api/get/context/3"
    },
    {
      "description": "Fedora + RHEL based",
      "done": false,
      "title": "Centos stream",
      "uri": "http://pytbak.ing.h4x0r3d.lan/api/get/context/4"
    }
  ]
}
```

**POST — create a new context:**

```
$ curl -i -H "Content-Type: application/json" -X POST -d '{"title":"Ubuntu 20.04 LTS", "description":"focal"}' http://pytbak.ing.h4x0r3d.lan/api/post/context
HTTP/1.1 201 CREATED
Content-Type: application/json

{
  "task": {
    "description": "focal",
    "done": false,
    "title": "Ubuntu 20.04 LTS",
    "uri": "http://pytbak.ing.h4x0r3d.lan/api/get/context/5"
  }
}
```

**PUT — update an existing context:**

```
$ curl -i -H "Content-Type: application/json" -X PUT -d '{"description":"Focal Fossa"}' http://pytbak.ing.h4x0r3d.lan/api/put/context/5
HTTP/1.1 200 OK
Content-Type: application/json

{
  "task": {
    "description": "Focal Fossa",
    "done": false,
    "title": "Ubuntu 20.04 LTS",
    "uri": "http://pytbak.ing.h4x0r3d.lan/api/get/context/5"
  }
}
```

**DELETE — remove a context:**

```
$ curl -i -H "Content-Type: application/json" -X DELETE http://pytbak.ing.h4x0r3d.lan/api/delete/context/5
HTTP/1.1 200 OK
Content-Type: application/json

{
  "result": true
}
```

Verify it's gone:

```
$ curl -i http://pytbak.ing.h4x0r3d.lan/api/get/context/5
HTTP/1.1 404 NOT FOUND
Content-Type: application/json

{
  "error": "Not found"
}
```

This application shows up throughout the blog — it's the backend behind the [API gateway post](/posts/kubernetes-apigw/), the [rate limiting tests](/posts/application-rate-limiting/), and various HPA experiments. Having a purpose-built test backend that you fully control makes platform testing much cleaner than hacking against real applications.