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Version: 3.8

Guidelines for creating an EKS cluster for ScalarDL Ledger

This document explains the requirements and recommendations for creating an Amazon Elastic Kubernetes Service (EKS) cluster for ScalarDL Ledger deployment. For details on how to deploy ScalarDL Ledger on an EKS cluster, see Deploy ScalarDL Ledger on Amazon EKS.

Before you begin​

You must create an EKS cluster based on the following requirements, recommendations, and your project's requirements. For specific details about how to create an EKS cluster, see the official Amazon documentation at Creating an Amazon EKS cluster.

Requirements​

When deploying ScalarDL Ledger, you must:

  • Create the EKS cluster by using Kubernetes version 1.21 or higher.
  • Configure the EKS cluster based on the version of Kubernetes and your project's requirements.
warning

For Byzantine fault detection in ScalarDL to work properly, do not deploy your application pods on the same EKS cluster as the ScalarDL Ledger deployment.

Recommendations (optional)​

The following are some recommendations for deploying ScalarDL Ledger. These recommendations are not required, so you can choose whether or not to apply these recommendations based on your needs.

Create at least three worker nodes and three pods​

To ensure that the EKS cluster has high availability, you should use at least three worker nodes and deploy at least three pods spread across the worker nodes. You can see the sample configurations of podAntiAffinity for making three pods spread across the worker nodes.

note

If you place the worker nodes in different availability zones (AZs), you can withstand an AZ failure.

Use 4vCPU / 8GB memory nodes for the worker node in the ScalarDL Ledger node group​

From the perspective of commercial licenses, resources for one pod running ScalarDL Ledger are limited to 2vCPU / 4GB memory. In addition to the ScalarDL Ledger pod, Kubernetes could deploy some of the following components to each worker node:

  • ScalarDL Ledger pod (2vCPU / 4GB)
  • Envoy proxy
  • Monitoring components (if you deploy monitoring components such as kube-prometheus-stack)
  • Kubernetes components

With this in mind, you should use a worker node that has at least 4vCPU / 8GB memory resources and use at least three worker nodes for availability, as mentioned in Create at least three worker nodes and three pods.

However, three nodes with at least 4vCPU / 8GB memory resources per node is the minimum environment for production. You should also consider the resources of the EKS cluster (for example, the number of worker nodes, vCPUs per node, memory per node, and ScalarDL Ledger pods), which depend on your system's workload. In addition, if you plan to scale the pods automatically by using some features like Horizontal Pod Autoscaling (HPA), you should consider the maximum number of pods on the worker node when deciding the worker node resources.

Configure Cluster Autoscaler in EKS​

If you want to scale ScalarDL Ledger pods automatically by using Horizontal Pod Autoscaler, you should configure Cluster Autoscaler in EKS too. For details, see the official Amazon documentation at Autoscaling.

In addition, if you configure Cluster Autoscaler, you should create a subnet in an Amazon Virtual Private Cloud (VPC) for EKS with the prefix (e.g., /24) to ensure a sufficient number of IPs exist so that EKS can work without network issues after scaling.

Create the EKS cluster on a private network​

You should create the EKS cluster on a private network (private subnet in a VPC) since ScalarDL Ledger does not provide any services to users directly via internet access. We recommend accessing ScalarDL Ledger via a private network from your applications.

Restrict connections by using some security features based on your requirements​

You should restrict unused connections in ScalarDL Ledger. To restrict unused connections, you can use some security features in AWS, like security groups and network access control lists.

The connections (ports) that ScalarDL Ledger uses by default are as follows:

  • ScalarDL Ledger
    • 50051/TCP (Accept the requests from a client)
    • 50052/TCP (accepts privileged requests from a client)
    • 50053/TCP (accepts pause and unpause requests from a scalar-admin client tool)
    • 8080/TCP (accepts monitoring requests)
  • Scalar Envoy (used with ScalarDL Ledger)
    • 50051/TCP (load balancing for ScalarDL Ledger)
    • 50052/TCP (load balancing for ScalarDL Ledger)
    • 9001/TCP (accepts monitoring requests for Scalar Envoy itself)
note
  • If you change the default listening port for ScalarDL Ledger in the configuration file (ledger.properties), you must allow connections by using the port that you configured.
  • You must also allow the connections that EKS uses itself. For more details about Amazon EKS security group requirements, refer to Amazon EKS security group requirements and considerations.