The WebSocket protocol enables persistent, low-latency, bidirectional communication between clients and servers. When a WebSocket service runs inside a Kubernetes cluster, a Cloud-native API Gateway can serve as the entry point to receive external requests and forward them to the appropriate backend based on routing rules. This topic describes how to deploy a WebSocket workload to an Container Service for Kubernetes (ACK) cluster and route its traffic through a Cloud-native API Gateway.
Prerequisites
-
You have created an ACK cluster. For more information, see Create an ACK managed cluster.
-
You have created a Cloud-native API Gateway instance. For more information, see Create a gateway instance.
Step 1: Deploy a WebSocket workload
For more information about how to deploy a stateless workload, see Create a stateless workload Deployment.
This example uses a Kubernetes Service resource to register the backend with CoreDNS for service discovery. The sample backend exposes several WebSocket endpoints. Apply the following manifest to your ACK cluster:
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: sockbin
name: sockbin-app
namespace: default
spec:
progressDeadlineSeconds: 600
replicas: 2
revisionHistoryLimit: 10
selector:
matchLabels:
app: sockbin
strategy:
rollingUpdate:
maxSurge: 25%
maxUnavailable: 25%
type: RollingUpdate
template:
metadata:
labels:
app: sockbin
spec:
containers:
- image: therebelrobot/sockbin
imagePullPolicy: Always
name: sockbin
ports:
- containerPort: 4080
protocol: TCP
resources:
limits:
cpu: 500m
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 30
---
apiVersion: v1
kind: Service
metadata:
labels:
app: sockbin
name: sockbin-service
namespace: default
spec:
ports:
- name: http
port: 4080
protocol: TCP
targetPort: 4080
selector:
app: sockbin
sessionAffinity: None
type: NodePortStep 2: Route WebSocket traffic
Add the ACK cluster as a service source for the gateway, and then add the Sockbin service.
Add a service source
Log on to the API Gateway console.
In the left-side navigation pane, click . In the top navigation bar, select a region.
On the Instance page, click the target instance ID.
In the left-side navigation pane, click Service. Then, click the Source tab.
-
Click Create Source, set the parameters, and then click OK.
Parameter
Description
Source Type
Select ACK.
ACK/ACK Serverless cluster
Select the cluster where the backend service is deployed.
Listen to Kubernetes Ingress
When enabled, Cloud-native API Gateway automatically detects changes to Ingress resources and applies the domain name and route configurations they define.
When disabled, the gateway stops listening to Ingress resources and removes any configurations previously applied from them.
NoteDomain name and route configurations manually set in the console override configurations from Ingress resources.
Add a service
Log on to the API Gateway console.
In the left-side navigation pane, click . In the top navigation bar, select a region.
On the Instance page, click the target instance ID.
In the left-side navigation pane, click Service. Then, click the Services tab.
-
Click Create Service, set the parameters, and then click OK.
Parameter
Description
Service Source
Select ACK.
Namespace
Select the namespace of the target cluster.
Services
Select the service from the list.
Add a route to the Sockbin service
-
Create an HTTP API. For more information, see Create an HTTP API.
Click the target API and click Create Route in the upper-left corner.
-
In the Create Route panel, set the parameters and then click Save and Publish.
Parameter
Description
Route Name
Enter
sockbin-route.Domain Name
Select the default domain name, *.
Path
Set the match type to Prefix and the path to
/.Scenario
Select Single Service.
Backend Services
Select the target Service and Service Port.
Verify the results
You can use either of the following methods to verify the WebSocket service.
Method 1: Test with the Sockbin UI
Open the gateway's public address in a browser to access the Sockbin service UI.
Method 2: Test using a WebSocket client
For example, use the following Python client to test a 1-second delayed response. Replace ip_addr with the public IP address of your gateway.
#!/usr/bin/env python
import asyncio
import websockets
async def hello():
async with websockets.connect("ws://ip_addr/delay/1000") as websocket:
await websocket.send("Hello Test")
text = await websocket.recv()
print(text)
asyncio.run(hello())