Container Service for Kubernetes:Deploy a Stable Diffusion Service in a production environment based on Knative

Prerequisites

• An ACK cluster that runs Kubernetes 1.24 or later is created, and the cluster contains GPU-accelerated nodes. For more information, see Create an ACK managed cluster.

  We recommend that you select ecs.gn5-c4g1.xlarge, ecs.gn5i-c8g1.2xlarge, or ecs.gn5-c8g1.2xlarge.

• Knative is deployed in the cluster. For more information, see Deploy Knative.

• Knative is connected to Managed Service for Prometheus and you can .

Procedure

With the development of generative AI technologies, an increasing number of developers attempt to improve R&D efficiency by using AI models. As a well-known AI-generated content (AIGC) project, Stable Diffusion can help users quickly and accurately generate desired scenes and pictures. However, you may face the following challenges when you use Stable Diffusion:

• The maximum throughput of a pod is limited. If an excessive number of requests are forwarded to the same pod, the pod becomes overloaded. To resolve this issue, you must limit the maximum number of concurrent requests that a pod can process.

• GPU resources are pricy and you want to use GPUs on demand and release GPUs during off-peak hours.

To resolve the preceding issues, ACK is integrated with Knative to support accurate concurrent request processing and auto scaling. This allows you to deploy a Stable Diffusion Service in a production environment based on Knative. The following figure shows how to deploy a Stable Diffusion Service in a production environment based on Knative.

Step 1: Deploy a Stable Diffusion Service

1. Log on to the ACK console. In the left-side navigation pane, click Clusters.

2. On the Clusters page, find the cluster that you want to manage and click its name. In the left-side navigation pane, choose Applications > Knative.

3. Deploy a Stable Diffusion Service.

   ACK Knative provides commonly used application templates. You can quickly deploy the Stable Diffusion Service by using an application template or a YAML file.

   Application template

   Click the Popular Apps tab and click Quick Deployment on the stable-diffusion card.

   After the deployment, you can click Services to view the deployment status in the Service list.

   The following figure shows that the Stable Diffusion Service is deployed.

   

   YAML

   On the Services tab, select default from the Namespace drop-down list and click Create from Template. Copy the following YAML template to the code editor and click Create to create a Service named knative-sd-demo.

   apiVersion: serving.knative.dev/v1
   kind: Service
   metadata:
     name: knative-sd-demo
     annotations:
       serving.knative.dev.alibabacloud/affinity: "cookie"
       serving.knative.dev.alibabacloud/cookie-name: "sd"
       serving.knative.dev.alibabacloud/cookie-timeout: "1800"
   spec:
     template:
       metadata:
         annotations:
           autoscaling.knative.dev/class: kpa.autoscaling.knative.dev
           autoscaling.knative.dev/maxScale: '10'
           autoscaling.knative.dev/targetUtilizationPercentage: "100"
           k8s.aliyun.com/eci-use-specs: ecs.gn5-c4g1.xlarge,ecs.gn5i-c8g1.2xlarge,ecs.gn5-c8g1.2xlarge  
       spec:
         containerConcurrency: 1
         containers:
         - args:
           - --listen
           - --skip-torch-cuda-test
           - --api
           command:
           - python3
           - launch.py
           image: yunqi-registry.cn-shanghai.cr.aliyuncs.com/lab/stable-diffusion@sha256:62b3228f4b02d9e89e221abe6f1731498a894b042925ab8d4326a571b3e992bc
           imagePullPolicy: IfNotPresent
           ports:
           - containerPort: 7860
             name: http1
             protocol: TCP
           name: stable-diffusion
           readinessProbe:
             tcpSocket:
               port: 7860
             initialDelaySeconds: 5
             periodSeconds: 1
             failureThreshold: 3

   If the Service is in the following state, the knative-sd-demo Service is created.

   

Step 2: Access the Stable Diffusion Service

1. On the Services tab, record the gateway IP address and default domain name of the Service.

2. Add the following information to the hosts file to map the domain name of the Service to the IP address of the gateway for the knative-sd-demo Service. The following sample code shows the content that is to be added to the hosts file.

   47.xx.xxx.xx knative-sd-demo.default.example.com # Replace the IP address and domain name with the actual values.

3. After you modify the hosts file, go to the Services tab, and click the default domain name of the knative-sd-demo Stable Diffusion Service to access the Service.

   If the following page appears, the access is successful.

   

Step 3: Enable auto scaling based on requests

1. Use the load testing tool hey to perform stress tests.

   Note

   For more information about the hey tool that is used for stress testing, see hey.

   hey -n 50 -c 5 -t 180 -m POST -H "Content-Type: application/json" -d '{"prompt": "pretty dog"}' http://knative-sd-demo.default.example.com/sdapi/v1/txt2img

   Send 50 requests with 5 concurrent requests in each batch and set the timeout period to 180 seconds.

   Expected output:

   Summary:
     Total:	252.1749 secs
     Slowest:	62.4155 secs
     Fastest:	9.9399 secs
     Average:	23.9748 secs
     Requests/sec:	0.1983
   
   
   Response time histogram:
     9.940 [1]	|■■
     15.187 [17]	|■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
     20.435 [9]	|■■■■■■■■■■■■■■■■■■■■■
     25.683 [11]	|■■■■■■■■■■■■■■■■■■■■■■■■■■
     30.930 [1]	|■■
     36.178 [1]	|■■
     41.425 [3]	|■■■■■■■
     46.673 [1]	|■■
     51.920 [2]	|■■■■■
     57.168 [1]	|■■
     62.415 [3]	|■■■■■■■
   
   
   Latency distribution:
     10% in 10.4695 secs
     25% in 14.8245 secs
     50% in 20.0772 secs
     75% in 30.5207 secs
     90% in 50.7006 secs
     95% in 61.5010 secs
     0% in 0.0000 secs
   
   Details (average, fastest, slowest):
     DNS+dialup:	0.0424 secs, 9.9399 secs, 62.4155 secs
     DNS-lookup:	0.0385 secs, 0.0000 secs, 0.3855 secs
     req write:	0.0000 secs, 0.0000 secs, 0.0004 secs
     resp wait:	23.8850 secs, 9.9089 secs, 62.3562 secs
     resp read:	0.0471 secs, 0.0166 secs, 0.1834 secs
   
   Status code distribution:
     [200]	50 responses

   The output shows that all 50 requests are successfully processed.

2. Run the following command to query the pods:

   watch -n 1 'kubectl get po'

   

   The output shows that five pods are created for the Stable Diffusion Service. This is because containerConcurrency: 1 is configured for the Service, which indicates that a pod can concurrently process at most 1 request.

Step 4: View the monitoring data of the Stable Diffusion Service

Knative provides out-of-the-box observability features. You can view the monitoring data of the Stable Diffusion Service on the Monitoring Dashboards of the Knative page. For more information about how to enable Knative dashboards, see View the Knative monitoring dashboard.

• In the Overview (average over the selected time range) section, you can view the number of Knative requests (Request Volume), request success rate (Success Rate), client errors (4xx), server errors (5xx), and pod scaling trend.

  

• In the Response Time section, you can view the response latency data of Knative, including the P50, P90, P95, and P99 response latency.

  

References

For more information about how to deploy AI inference services in Knative, see Best practices for deploying AI inference services in Knative.