#Tunnel Setup & Use

#Setting up Tunnels

A tunnel is a way to expose your internal services to the Zuplo gateway without exposing it to the public internet. Your Zuplo Gateway accesses those services through the service:// protocol.

The easiest way to deploy your tunnel is using a Docker container. The three basic requirements for deploying a secure tunnel with Docker are:

1. A tunnel secret that is provided to the Docker container as an environment variable named TUNNEL_TOKEN (the secret is provided by the Zuplo CLI when you create the tunnel. See creating a tunnel)
2. The ability for the tunnel service to make an outbound connection to the public internet to establish the secure tunnel.
3. The ability for the tunnel service to make a request to your internal API by a DNS address. (i.e. https://my-service.local/api).

The tunnel can run anywhere you can deploy a Docker container. Where you deploy depends on your specific setup. To run the Docker container on your own infrastructure, refer to instructions from your cloud provider or contact Zuplo support for assistance.

Below are a few option for deploying the tunnel.

• Deploying Docker containers on Azure
• Deploying Docker containers on AWS ECS
• Deploying container images to GCP

The docker container is zuplo/tunnel and is available on Docker Hub.

Your running container needs a single environment variable named TUNNEL_TOKEN. You should store the value as a secret using the recommended means of secret storage and environment variable injection for your platform.

#Configuring Services using Tunnels

Now that you have your tunnel set up, refer to configuring services through the CLI for how to expose your services.

#Using Services Exposed through Tunnels in Code

Once set up, the services in the tunnels can be treated like any API host that you call from your Zuplo gateway. Each service exposed through tunnels is called with the URL schema service://, so if your service is named my-awesome-service you will call it using the URL service://my-awesome-service.

This URL can be used in code as shown below.

import { ZuploContext, ZuploRequest } from "@zuplo/runtime";

export default async function (request: ZuploRequest, context: ZuploContext) {
  const response = await fetch("service://my-awesome-service/hello-world");
  if (response.status > 399) {
    return "It didn't work. :(";
  } else {
    return response;
  }
}

It is common to have multiple services for each of your internal environments. Each service can be restricted so that it is only accessible by specific Zuplo environments. For example, you might have two services one for production and one for staging.

• service://my-awesome-service-prod (Production)
• service://my-awesome-service-staging (Staging)

#Using Services Exposed through Tunnels in Config

Services can also be used in routes.oas.json file such as with the URL Rewrite handler. To call a tunnel service simply use it as part of the rewrite url as shown in the image below.

#Service Environment Variables

When using these services in your code or configuration, it is often useful to store the values as an environment variable. This way you can change which environment calls which tunnel without changing code or configuration.

For the production environment you would set the BASE_SERVICE_URL to the production service name. See this document for more about Environment Variables

BASE_SERVICE_URL=service://my-awesome-service-prod

And for staging, you would use the staging service name.

BASE_SERVICE_URL=service://my-awesome-service-staging

In your handler code or other configuration, the service can be accessed using the environment variable.

import { ZuploContext, ZuploRequest, environment } from "@zuplo/runtime";

export default async function (request: ZuploRequest, context: ZuploContext) {
  const response = await fetch(`${environment.BASE_SERVICE_URL}/hello-world`);
  if (response.status > 399) {
    return "It didn't work. :(";
  } else {
    return response;
  }
}

Environment variables can also be used in configuration, such as the URL Rewrite handler as shown below.

#Tunnel Upgrades

Zuplo publishes a new release of the tunnel Docker image about once per month or whenever Cloudflare ships a release to their underlying tunnel tools. The most recent version of the Docker Image is always tagged with the latest tag. We recommend periodically checking and upgrading the tunnel to the latest release to ensure you have the latest security and performance updates.

We recommend testing each release of the tunning in a staging environment before rolling out to production.

#Troubleshooting

For troubleshooting see this document.