Deploying Gate with Kubernetes as API Gateway

In this example, we will deploy Gate in K8s as API Gateway that routes requests to a defined service based on configured request URL.

info

This is just an example of deployment. You should adjust it to your infrastructure.

Prerequisites

This tutorial uses Gate's Docker image.

Architecture

Example configuration

gate-api-gateway.yaml

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: gate
spec:
  replicas: 3
  selector:
    matchLabels:
      app: gate
  template:
    metadata:
      labels:
        app: gate
    spec:
      containers:
        - name: gate
          image: slashid/gate
          command: [gate, --env]
          ports:
            - containerPort: 8080
          env:
            - name: GATE_PORT
              value: "8080"
            - name: GATE_DEFAULT_TARGET
              value: http://products.default.svc.cluster.local:80/
            - name: GATE_URLS_0_PATTERN
              value: "*/products"
            - name: GATE_URLS_0_TARGET
              value: http://products.default.svc.cluster.local:80/
            - name: GATE_URLS_1_PATTERN
              value: "*/orders"
            - name: GATE_URLS_1_TARGET
              value: http://orders.default.svc.cluster.local:80/
            - name: GATE_LOG_LEVEL
              value: debug
            - name: GATE_LOG_FORMAT
              value: text
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: products
spec:
  replicas: 3
  selector:
    matchLabels:
      app: products
  template:
    metadata:
      labels:
        app: products
    spec:
      containers:
        - name: products
          image: slashid/example-service
          env:
            - name: PORT
              value: "80"
            - name: SERVICE_NAME
              value: products
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: orders
spec:
  replicas: 3
  selector:
    matchLabels:
      app: orders
  template:
    metadata:
      labels:
        app: orders
    spec:
      containers:
        - name: orders
          image: slashid/example-service
          env:
            - name: PORT
              value: "80"
            - name: SERVICE_NAME
              value: orders
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: gate
  name: gate
spec:
  externalTrafficPolicy: Local
  ports:
    - port: 8080
      targetPort: 8080
  selector:
    app: gate
  sessionAffinity: None
  type: LoadBalancer
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: products
  name: products
spec:
  ports:
    - port: 80
      targetPort: 80
  selector:
    app: products
  sessionAffinity: None
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: orders
  name: orders
spec:
  ports:
    - port: 80
      targetPort: 80
  selector:
    app: orders
  sessionAffinity: None

Testing locally

You can test this setup locally (for example, with Docker Desktop Kubernetes).

kubectl apply -f gate-api-gateway.yaml

Once the deployment is running, you can check if requests go through Gate.

curl -v http://localhost:8080/
> GET / HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.79.1
> Accept: */*
>
< HTTP/1.1 200 OK
< Content-Length: 81
< Content-Type: application/json
< Servicehostname: products-57c5667b6c-kg6qh
< Servicename: products
< Via: gate
<
{
    "service_hostname": "products-57c5667b6c-kg6qh",
    "service_name": "products"
}

If the Via: 1.0 gate header is present, it means that everything works properly and gate is up and running.

curl -v http://localhost:80/products
> GET /products HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.79.1
> Accept: */*
>
< HTTP/1.1 200 OK
< Content-Length: 81
< Content-Type: application/json
< Servicehostname: products-57c5667b6c-kg6qh
< Servicename: products
< Via: 1.0 gate
<
{
    "service_hostname": "products-57c5667b6c-kg6qh",
    "service_name": "products"
}

curl -v http://localhost:80/orders

> GET /orders HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.79.1
> Accept: */*
>
< HTTP/1.1 200 OK
< Content-Length: 77
< Content-Type: application/json
< Servicehostname: orders-66cfb49594-mw6nf
< Servicename: orders
< Via: 1.0 gate
<
{
    "service_hostname": "orders-66cfb49594-mw6nf",
    "service_name": "orders"
}