userspace

CSL7510-VCC-Project

Implementation of RAP ( Resource Adaptive Proxy)

What is Resource Adaptive Proxy

Resource Adaptive Proxy (RAP) enhances load balancing by periodically monitoring the resource and network status of each pod and worker node in a K8s cluster. It prioritizes local handling of requests and, if the local node is overloaded, intelligently forwards requests to the best-performing node in the cluster, considering resource availability. Experimental results demonstrate that RAP significantly improves throughput and reduces request latency compared to K8s' default load-balancing mechanism.

For knowing more about RAP, refer to https://www.mdpi.com/1424-8220/22/8/2869.

Adding RAP to K8s cluster

There are some prerequisites for adding RAP to your cluster. For RAP to work, you need to enable the userspace mode. Now, the userspace mode is deprecated in Kubernetes v1.23, therefore, we are using Kubernetes 1.21.10. Also, install Golang in your workstation.

• Create 3 nodes with 1 master node and 2 worker nodes
  • We have used GCP for creating the instances at different locations and used the provided terraform code for launching the instances. To use the terraform commands:

    cd infra/
    cp tfvars.example terraform.tfvars
    

  • You need to download a service account key from GCP and set its path in the gcp_svc_key variable in the terraform.tfvars file. Also, you need to set the the gcp_project and gcp_svc_email variables in the terraform.tfvars file. Then run the following commands:

    terraform init
    terraform plan
    terraform apply
    

  • Launch the K8s cluster with kubeadm.
• Now build the kube-proxy with the RAP code
  • Go ahead and clone the release-1.21 being checked out.

    git clone --branch release-1.21 https://github.com/kubernetes/kubernetes.git
    

  • change the code at pkg/proxy/userspace/roundrobin.go with the code provided at rap.go
  • Now build the kube-proxy with the command at the root of the repository

    make kube-proxy
    

  • Now build the docker image with the new kube-proxy.
    • Now let's go ahead and build the new docker image with the command using the provided Dockerfile

      docker build -t <your-docker-hub-username>/kube-proxy-rap:v1.21.10 .
      

      You need to run this command at the location where both Dockerfile and built kube-proxy are present. Take a look at the Dockerfile for better understanding.

    • push the new docker image to the hub so that later it can be pulled by our k8s cluster

      docker push  <your-docker-hub-username>/kube-proxy-rap:v1.21.10
      

  • Now replace the image of kube-proxy that is being used by the daemon sets created by kubeadm

    kubectl edit daemonset kube-proxy -n kube-system
    kubectl rollout restart daemonset kube-proxy -n kube-system
    

  • Now this will spin up our new kube-proxy with rap enabled, and make sure that userspace mode is enabled. Refer to this to know how to change it.