Scalable Streaming ASR with Amazon AWS

This repository contains all necessary files and instructions to deploy a streaming Automatic Speech Recognition (ASR) service with AWS Elastic Kubernetes Service (EKS).

📦 Pipeline overview

---

📦 Prerequisites

Make sure to install the following tools:

• AWS CLI
• kubectl
• eksctl
• helm

---

🔐 IAM Policy Setup

Ensure the following policies are attached to your IAM user:

• AmazonEBSCSIDriverPolicy
• AmazonEKS_CNI_Policy
• AmazonEKSBlockStoragePolicy
• AmazonEKSClusterPolicy
• AmazonEKSComputePolicy
• AmazonEKSFargatePodExecutionRolePolicy
• AmazonEKSLoadBalancingPolicy
• AmazonEKSLocalOutpostClusterPolicy
• AmazonEKSNetworkingPolicy
• AmazonEKSServicePolicy
• AmazonEKSVPCResourceController
• AmazonEKSWorkerNodeMinimalPolicy
• AmazonEKSWorkerNodePolicy
• AmazonSSMManagedInstanceCore
• AutoScalingFullAccess
• AWSFaultInjectionSimulatorEKSAccess

---

📁 Project Structure

File/Folder	Description
asr.py	ASR model class. Modify this file to use your own ASR model. Implement predict(self, messages) method.
asr_server.py	FastAPI application endpoint, manages request queue and client pool.
audios/	Sample audios for testing.
client_logs/	Logging for client call results.
client.py	Simple script for sending streaming audios and receiving ASR transcription.
client.sh	Bash script for simulating multiple client calls.
config.py	Configuration for the ASR server and clients.
cluster.yaml	Defines EKS cluster parameters.
pre-pull.yaml	Pull docker image immediately when a new node is provisioned
priority-classes.yaml	Set deployment pod higher priority than reversed node (for over provisioning)
cluster-overprovisioner.yaml	Config for over provisioning
deployment.yaml	ASR pod deployment configuration.
Dockerfile	For building the ASR Docker image.
requirements.txt	Python dependencies for Docker image.
ebs-csi-policy.json	EBS CSI driver policy.
gp2-immediate.yaml	Custom persistent volume configuration.
hpa.yaml	KEDA-based HPA configuration.
iam_policy.json	IAM policy for load balancing.
ingress.yaml	ALB Ingress configuration.
pvc.yaml	Persistent Volume Claim configuration.
service-monitor.yaml	Prometheus service monitor config.
service.yaml	ASR service definition.
time-slicing-config-all.yaml	NVIDIA GPU time-sharing config.

---

🛠 Cluster Setup

Define Environment Variables

CLUSTER_NAME="asr-cluster"
REGION="eu-west-1"
ACCOUNT_ID="YOUR_ACCOUNT_ID"
POLICY_NAME="AWSLoadBalancerControllerIAMPolicy"
SA_NAME="aws-load-balancer-controller"

🛠 Create the EKS Cluster

Edit and adjust parameters in cluster.yaml as needed.

eksctl create cluster -f cluster.yaml
aws eks --region $REGION update-kubeconfig --name $CLUSTER_NAME

🚀 Install AWS Load Balancer Controller

helm repo add eks https://aws.github.io/eks-charts
helm repo update

curl -o iam_policy.json https://github.com/raw/kubernetes-sigs/aws-load-balancer-controller/main/docs/install/iam_policy.json

aws iam create-policy \
  --policy-name $POLICY_NAME \
  --policy-document file://iam_policy.json

eksctl utils associate-iam-oidc-provider --region $REGION --cluster $CLUSTER_NAME --approve

eksctl create iamserviceaccount \
  --cluster $CLUSTER_NAME \
  --namespace kube-system \
  --name $SA_NAME \
  --attach-policy-arn arn:aws:iam::$ACCOUNT_ID:policy/$POLICY_NAME \
  --approve

helm install $SA_NAME eks/aws-load-balancer-controller \
  -n kube-system \
  --set clusterName=$CLUSTER_NAME \
  --set serviceAccount.create=false \
  --set serviceAccount.name=$SA_NAME \
  --set region=$REGION \
  --set vpcId=$VPC_ID

🔊 ASR Server Implementation

Already implemented, files to modify if needed:
 - asr_server.py
 - asr.py
 - config.py
 - client.py
 - client.sh

We use the FastConformer model from Nemo ASR hub as the serving ASR model. You can change the ASR model by modifying asr.py file.

In this project we use STT En FastConformer Hybrid Transducer-CTC Large Streaming Multi . Please download the model and put it in the current directory and name the model as stt_en_fastconformer_hybrid_large_streaming_multi.nemo (just to make sure the Docker build working prorperly).

🐳 Build & Push Docker Image

Change to your docker_repo if needed. If you want to use my already built Docker image, you can skip this step

DOCKER_REPO="mailong25/asr-server"
docker build -t $DOCKER_REPO .
docker push $DOCKER_REPO

🐳 Init setup

kubectl apply -f pre-pull.yaml
kubectl apply -f priority-classes.yaml

📦 Deploy ASR Application

Edit deployment.yaml, service.yaml, and ingress.yaml if needed.

kubectl apply -f deployment.yaml
kubectl apply -f service.yaml
kubectl apply -f ingress.yaml
kubectl get pods -A

🧪 Test ASR Service

• Locate Load Balancer DNS from your AWS Console.
• Update SERVER_URI = Load Balancer DNS in config.py.
• Run a test:

python client.py

Set up for the autoscaling part

📈 Set Up Prometheus for Monitoring

eksctl utils associate-iam-oidc-provider --region=$REGION --cluster=$CLUSTER_NAME --approve

eksctl create iamserviceaccount \
  --region $REGION \
  --name ebs-csi-controller-sa \
  --namespace kube-system \
  --cluster $CLUSTER_NAME \
  --attach-policy-arn arn:aws:iam::aws:policy/service-role/AmazonEBSCSIDriverPolicy \
  --approve \
  --role-only \
  --role-name AmazonEKS_EBS_CSI_DriverRole

eksctl create addon --name aws-ebs-csi-driver --cluster $CLUSTER_NAME \
  --service-account-role-arn arn:aws:iam::$(aws sts get-caller-identity --query Account --output text):role/AmazonEKS_EBS_CSI_DriverRole --force

kubectl apply -f gp2-immediate.yaml
kubectl apply -f pvc.yaml

helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm repo update
helm install prometheus prometheus-community/kube-prometheus-stack

Create a ServiceMonitor:

kubectl apply -f service-monitor.yaml
kubectl port-forward svc/prometheus-kube-prometheus-prometheus 9090:9090

For monitoring, in browser (http://localhost:9090), run this to check average response latency

avg(rate(response_latency_seconds_sum[2m]) / clamp_min(rate(response_latency_seconds_count[2m]), 1e-9))

📊 Horizontal Pod Autoscaling with KEDA using prometheus metric

helm repo add kedacore https://kedacore.github.io/charts
helm repo update
helm install keda kedacore/keda
kubectl apply -f hpa.yaml

Now spawn multiple clients to test if the HPA work

sh client.sh 5 5

📈 Setup Cluster Autoscaler

aws iam create-policy \
  --policy-name AmazonEKSClusterAutoscalerPolicy \
  --policy-document file://<(cat <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "autoscaling:DescribeAutoScalingGroups",
        "autoscaling:DescribeAutoScalingInstances",
        "autoscaling:DescribeLaunchConfigurations",
        "autoscaling:DescribeTags",
        "autoscaling:SetDesiredCapacity",
        "autoscaling:TerminateInstanceInAutoScalingGroup",
        "ec2:DescribeLaunchTemplateVersions"
      ],
      "Resource": "*"
    }
  ]
}
EOF
)

eksctl utils associate-iam-oidc-provider --region=$REGION --cluster=$CLUSTER_NAME --approve

eksctl create iamserviceaccount \
  --cluster $CLUSTER_NAME \
  --namespace kube-system \
  --name cluster-autoscaler \
  --attach-policy-arn arn:aws:iam::$ACCOUNT_ID:policy/AmazonEKSClusterAutoscalerPolicy \
  --approve \
  --override-existing-serviceaccounts

helm repo add autoscaler https://kubernetes.github.io/autoscaler
helm repo update

helm upgrade --install cluster-autoscaler autoscaler/cluster-autoscaler \
  --namespace kube-system \
  --set autoDiscovery.clusterName=$CLUSTER_NAME \
  --set awsRegion=$REGION \
  --set rbac.serviceAccount.name=cluster-autoscaler \
  --set rbac.serviceAccount.create=false \
  --set fullnameOverride=cluster-autoscaler \
  --set extraArgs.balance-similar-node-groups=true \
  --set extraArgs.skip-nodes-with-system-pods=false \
  --set extraArgs.scale-down-enabled=true \
  --set extraArgs.scale-down-unneeded-time=2m \
  --set extraArgs.scale-down-delay-after-delete=2m \
  --set extraArgs.scale-down-delay-after-add=2m \
  --set extraArgs.max-node-provision-time=15m \
  --set extraArgs.scan-interval=1m

[Optional] 📈 Setup Cluster Overprovisioning

• Keep a buffer of running reserved pods to handle sudden spikes in demand during peak periods. This helps avoid increased latency caused by delays in provisioning new nodes.

kubectl apply -f cluster-overprovisioner.yaml

🔁 Now Run Load Test

This will gradually spawn 40 clients to call the ASR server.

sh client.sh 40 30

The Cluster should automatically scale up the number of pods/nodes during peak traffic periods. Then gradually scale down pods/nodes as the number of requests decreasing. You can use Prometheus for monitoring the number of requests/latency from each pod:

• Total Requests per Minute:

sum(rate(response_latency_seconds_count[1m]))

• Average Response Latency:

avg(rate(response_latency_seconds_sum[1m]) / clamp_min(rate(response_latency_seconds_count[1m]), 1e-9))