Guide for Soroban RPC server on Kubernetes with DigitalOcean

Prerequisites

• A fully registered domain name with an available A record
  • Example: rpc.your_domain.com
  • You can purchase a domain from Namecheap or any domain registrar
  • This domain will be used to create a custom endpoint for your RPC server
• An API testing client.
  • Recommended: https://httpie.io/
  • Alternative: Postman or curl
  • This will be used to verify the functionality of your RPC server

Introduction

This tutorial will guide you through the process of deploying your own Soroban RPC (Remote Procedure Call) server on DigitalOcean's Kubernetes platform. Soroban is Stellar's smart contract platform, and having your own RPC server allows you to interact with the Stellar network for smart contract operations without relying on public infrastructure.

Benefits of deploying your own Soroban RPC server:

• Increased reliability and uptime
• Control over server resources and configuration
• Potential for better performance compared to public endpoints

By the end of this tutorial, you'll have a fully functional Soroban RPC server accessible via your custom domain.

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Target audience

This tutorial is designed for developers with:

• Intermediate knowledge of Kubernetes
• Basic familiarity with DigitalOcean's cloud platform
• Interest in Stellar blockchain development

While prior experience with these technologies is helpful, we'll provide detailed explanations for each step.

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Step by Step Instructions

Step - Create Kubernetes Cluster in DigitalOcean

A Kubernetes cluster on DigitalOcean has one or more node pools. Each node pool consists of a group of identical worker nodes. Worker nodes are built on Droplets. For this tutorial, we can build a cluster with two worker nodes in one node pool.

Create Kubernetes cluster in DigitalOcean

‍https://docs.digitalocean.com/products/kubernetes/how-to/create-clusters/#create-a-cluster-using-the-control-panel

a. Log into your DigitalOcean account and navigate to the Kubernetes section.

b. Click "Create Cluster" and choose the following settings:

• Cluster capacity: 2 GB RAM / 1 vCPU per node
• Node count: 2 nodes (minimum for basic redundancy)
• Datacenter region: Choose the closest to your target users
• Cluster name: e.g., "soroban-rpc-cluster"

c. Click "Create Cluster" and wait for provisioning (this may take several minutes).

Rationale: This cluster configuration provides a balance between cost and reliability for a personal RPC server.

If you want to create a single node cluster, you will have to select a larger node size.

Step - Follow Getting Started with Kubernetes guide under the Overview Tab

While the cluster is being provisioned, we can follow along with the rest of the setup instructions that appear under the Overview tab by clicking on Get Started

Connecting to Kubernetes

The first step in connecting to Kubernetes requires additional applications:

Install doctl

https://docs.digitalocean.com/reference/doctl/how-to/install/

Install kubectl

https://kubernetes.io/docs/tasks/tools/

Install Helm

https://helm.sh/docs/intro/install/

Verify connectivity to Kubernetes

Rationale: These tools are essential for managing your Kubernetes cluster and deploying applications.

Connect to Your Newly Provisioned Cluster Using doctl

Verify Connectivity

kubectl cluster-info

Display addresses of the control plane and cluster services

doctl kubernetes cluster list

Displays a variety of commands that help manage your cluster via DigitalOcean's API

Step - Add SDF Helm Chart Repository

Stellar Development Foundation (SDF) provides Helm charts for easy deployment of Stellar applications.

Add SDF Helm Chart Repository to Your System:

We will first need to add the Helm Chart repository to our system using the following helm commands:

The helm repo add command adds the chart repository to your local Helm registry

helm repo add stellar https://helm.stellar.org/charts

The helm repo update command updates the information of available charts locally from the chart repositories you have added to your Helm registry.

helm repo update

Rationale: This step allows you to easily install and manage Stellar applications on your Kubernetes cluster.

Step - Deploy Soroban RPC Workload

Now that we have added the SDF chart repository to our local registry and updated the charts that are available to us, we can now deploy a workload using one of the charts available.

a. Create a local deployment configuration file:

• Start with the testnet configuration: https://github.com/stellar/helm-charts/blob/main/charts/soroban-rpc/testnet-values.yaml
• Save this as soroban-rpc-values.yaml on your local machine

Since we will be connecting our RPC server to testnet, we can uncomment update Soroban RPC image tag to the latest version

sorbanRpc:
 ....
    tag: latest

For the ingress section in the configuration file, add your fully registered domain name for the host value

• host: rpc.your_domain
  

We also want to uncomment and update the Ingress class name

• ingressClassName:nginx
  

After we have finished with our configuration file, we can use that to install Soroban RPC into our Kubernetes cluster

helm install my-soroban-rpc stellar/soroban-rpc --values=testnet-values.yaml

Rationale: This configuration sets up your RPC server to use the latest version and prepares it for public access via your domain.

Step - Verify the Service Is Up and Running

Check the status of your service

kubectl get service

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Check the status of your pods

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You should see pods related to Soroban RPC in a "Running" state.

Step - Installing the Kubernetes Nginx Ingress Controller

https://www.digitalocean.com/community/tutorials/how-to-set-up-an-nginx-ingress-on-digitalocean-kubernetes-using-helm

Even though we have verified that our service is running on our cluster in the previous step, we still cannot access the service from the outside. For that we will need to create an ingress, an ingress is a way for us to expose our service to the outside world. We will use the nginx ingress and we will first need to add the Nginx Helm Chart Repository to our system.

The Nginx Ingress Controller manages external access to your services.

Add Nginx Ingress Helm Chart Repository to Your System:

helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx
helm repo update

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We can now install the nginx ingress into our Kubernetes cluster

helm install nginx-ingress ingress-nginx/ingress-nginx --set controller.publishService.enabled=true

Run this command to watch the load balancer become available. This process creates a load balancer in the cluster resource group in DigitalOcean.

kubectl --namespace default get services -o wide -w nginx-ingress-ingress-nginx-controller

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Rationale: The Ingress Controller allows external traffic to reach your RPC server securely.

Step - Update DNS records to point to DigitalOcean loadbalancer

a. Go to your domain registrar's DNS management page.

b. Create an A record:

• Name: rpc (or your chosen subdomain)
• Value: The External-IP from the previous step

c. Save the changes and wait for DNS propagation (can take up to 48 hours, but often much faster).

Rationale: This step connects your domain name to the DigitalOcean load balancer, allowing access to your RPC server.

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Step - Verify You Can Connect to RPC Service Through Your Fully Qualified Domain

Once DNS has propagated, test your RPC server:

http POST https://rpc.your_domain jsonrpc="2.0"  id=867 method="getHealth"

Step - Cleanup

If you need to remove the deployment:

1. Delete Helm releases

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1. Delete the Kubernetes cluster in the DigitalOcean dashboard.
2. Remove the DNS A record from your domain registrar.

Maintenance Tips

• Regularly update your Soroban RPC server:

• Monitor cluster health using DigitalOcean's dashboard or kubectl commands.
• Set up log aggregation for easier troubleshooting.

Additional Resources:

1. ‍https://docs.digitalocean.com/products/kubernetes/how-to/create-clusters/#create-a-cluster-using-the-control-panel‍
2. https://www.digitalocean.com/community/tutorials/how-to-set-up-an-nginx-ingress-on-digitalocean-kubernetes-using-helm‍
3. https://docs.digitalocean.com/products/kubernetes/getting-started/operational-readiness/enable-https/‍
4. https://github.com/stellar/helm-charts/
5. https://soroban.stellar.org/docs

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