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Configure Site-to-Site Connectivity for APIs

This guide provides step-by-step instructions for using ngrok for site-to-site connectivity. This example shows you how to run the ngrok agent at an external site to get access to locally running APIs.

The connection will be unencrypted. ngrok recommends configuring end-to-end encryption with mTLS. However, we understand there are times when you may wish to configure an unencrypted connection such as during testing or proof of concept. Therefore, we provide the steps in this guide, but we recommend configuring mTLS before going to production.

Install the ngrok agent​

Download the appropriate version and install it on the same subnet as the APIs you want to access.

Get an ngrok API Key​

Create an ngrok API key using the ngrok dashboard. Make sure you save the API key before you leave the screen because it won't be displayed again.

Configure a custom agent ingress address​

Configuring a custom agent ingress address allows you to provide your customers with a dedicated URL to connect to the ngrok platform. Since your customers will connect using your subdomain, they can safely block other ngrok domains to control the tunnels started in their network. You'll provide a subdomain you own, such as connect.{YOUR_DOMAIN}, and delegate DNS (Domain Name Service) control of that subdomain to ngrok.

Create the agent ingress address​

Use the ngrok API to create the custom agent address by running the command below, substituting your own values for the variables:

curl \
-X POST \
-H "Authorization: Bearer {API_KEY}" \
-H "Content-Type: application/json" \
-H "Ngrok-Version: 2" \
-d '{"description":"{DESCRIPTION}","domain": “connect.{YOUR_DOMAIN}”}' \
https://api.ngrok.com/agent_ingresses

You should receive a 201 response similar to the following:

{
	"id": "agin_2esRkfoq4frGvOVUmfhytlr2zS3",
	"uri": "/agent_ingresses/agin_2esRkfoq4frGvOVUmfhytlr2zS3",
	"description": "Custom ingress address for site-to-site connectivity",
	"domain": "connect.configurable-domain.com",
	"ns_targets": [
		"ns-1329.awsdns-38.org",
		"ns-737.awsdns-28.net",
		"ns-1940.awsdns-50.co.uk",
		"ns-427.awsdns-53.com"
	],
	"region_domains": [
		"tunnel.us.connect.configurable-domain.com",
		"tunnel.us-cal-1.connect.configurable-domain.com",
		"tunnel.eu.connect.configurable-domain.com",
		"tunnel.au.connect.configurable-domain.com",
		"tunnel.ap.connect.configurable-domain.com",
		"tunnel.jp.connect.configurable-domain.com",
		"tunnel.sa.connect.configurable-domain.com",
		"tunnel.in.connect.configurable-domain.com"
	],
	"created_at": "2024-04-09T19:37:23Z",
	"certificate_management_policy": null,
	"certificate_management_status": null
}

Save the values from the ns_targets property and the region_domains property as you'll use them later.

Update your DNS​

Create an NS record in your DNS provider's registry for each ns_targets value from the response above, using connect as the name for each entry. The screenshot is from AWS Route53, but you can use any DNS provider you choose.

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You should have four new records when you’re done.

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You can run the following command to get the values you need if you didn't save the response.

-X GET \
-H "Authorization: Bearer {API_KEY}" \
-H "Ngrok-Version: 2" \
https://api.ngrok.com/agent_ingresses

Create a custom wildcard domain​

Next, create a custom wildcard domain, which will allow you to create endpoints and receive traffic on any subdomain of your domain.

For example, you might create *.customer1.{YOUR_DOMAIN}. You would then be able to create endpoints on app.customer1.{YOUR_DOMAIN} and dev.customer1.{YOUR_DOMAIN}. It can be helpful to create a separate subdomain for each customer site you wish to connect to.

Run the following command, substituting your API key for {API_KEY} and your domain for {YOUR_DOMAIN}:

curl \
-X POST \
-H "Authorization: Bearer {API_KEY}" \
-H "Content-Type: application/json" \
-H "Ngrok-Version: 2" \
-d '{"domain":"*.customer1.{YOUR_DOMAIN}","region":"us"}' \
https://api.ngrok.com/reserved_domains

You should receive a 201 response similar to the following:

{
	"id": "rd_2euR3S7Mt07gRC6NlVGcXtghElK",
	"uri": "https://api.ngrok.com/reserved_domains/rd_2euR3S7Mt07gRC6NlVGcXtghElK",
	"created_at": "2024-04-10T12:31:16Z",
	"domain": "*.customer1.configurable-domain.com",
	"region": "",
	"cname_target": "hn9tzsiu5lnlbhcl.4wsgv9l5wfesschhy.ngrok-cname.com",
	"http_endpoint_configuration": null,
	"https_endpoint_configuration": null,
	"certificate": null,
	"certificate_management_policy": {
		"authority": "letsencrypt",
		"private_key_type": "ecdsa"
	},
	"certificate_management_status": {
		"renews_at": null,
		"provisioning_job": {
			"error_code": null,
			"msg": "Managed certificate provisioning in progress.",
			"started_at": "2024-04-10T12:31:16Z",
			"retries_at": null
		}
	},
	"acme_challenge_cname_target": "mpgy8nkj.acme-challenge.ngrok-dns.com"
}

You'll need values from the response in the next section.

Update DNS records​

Next, add two CNAME records to your DNS provider's registry, providing values from the previous response.

First add a CNAME record for the wildcard subdomain you just created.

alt-text

Then add another record for the ACME (Automated Certificate Management Environment) validation. For the record, enter acme_challenge_cname_target, and use the value of the
acme_challenge_cname_target property from from previous response for the value.

Verify DNS​

Use the ngrok dashboard to verify that you’ve configured DNS correctly.

  1. Login to the ngrok dashboard.
  2. Click Domains in the left-hand navigation menu.
  3. Click on your wildcard domain under Domain.
  4. Click 2 targets next to DNS Targets in the panel displayed on the right-hand side of the screen, as denoted by the arrow in the screenshot below.

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  1. Click Check Status, as denoted by the arrow in the screenshot below.

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  1. You should see a successful response similar to the screenshot below.

alt-text

Create a bot user​

Now, you’ll create a bot user so that in the next section, you can create an agent authtoken independent of any user account. Recall from Chapter 2 that a bot user does not belong to a particular user account. Run the following command to create a new bot user, providing your API key and a description:

curl \
-X POST \
-H "Authorization: Bearer {API_KEY}" \
-H "Content-Type: application/json" \
-H "Ngrok-Version: 2" \
-d '{DESCRIPTION}' \
https://api.ngrok.com/bot_users

You should receive a 201 response similar to the following:

{
	"id": "bot_2fmwUXhnImKswMgZKCsx7cnbt2l",
	"uri": "https://api.ngrok.com/bot_users/bot_2fmwUXhnImKswMgZKCsx7cnbt2l",
	"name": "new bot user from API",
	"active": true,
	"created_at": "2024-04-29T19:39:36Z"
}

Create the agent authtoken​

You should start each agent using a separate authtoken, and that token should belong to a bot user.

To create an authtoken, login to the ngrok dashboard and click Authtokens under Tunnels, then click Add a Tunnel Authtoken. For Owner, select the bot user you use created, and select bind:*.customer1.{YOUR_DOMAIN} for the ACL Rules. This ACL will allow an agent with the authtoken to create tunnels on any subdomain of customer1.{YOUR_DOMAIN}.

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Configure the ngrok agent API​

You can use the ngrok agent API to start and stop tunnels remotely, collect and replay captured requests, and collect stats and metrics.

The API runs on localhost:4040 wherever the agent runs, but you can start an ngrok tunnel to make the API available remotely.

Please note that tunnels started with the agent API do not persist in the event of an agent restart or network outage.

Update ngrok.yml​

Create a tunnel definition in the ngrok.yml config file. You can then run the ngrok agent and start and stop tunnels as needed using the ngrok agent API.

You'll need to modify the ngrok.yml config file before running the agent. You can modify the file that resides in the default location:

  • Linux: ~/.config/ngrok/ngrok.yml
  • MacOS (Darwin): ~/Library/Application Support/ngrok/ngrok.yml
  • Windows: %HOMEPATH%\AppData\Local\ngrok\ngrok.yml

Rather than edit the default ngrok.yml config file, you can provide your customer with a separate config file. This keeps your config separate from their existing ngrok.yml config file. You can then pass it as an argument when you run the ngrok agent. ngrok merges all config files, and you won't need to modify your customer's config file. This is useful when your customer already uses ngrok and you wish to use the existing agent to serve the ngrok agent API.

Refer to the region_domain values you saved when you created the custom agent ingress address. These are custom addresses for ngrok’s global Points of Presence (POPs). Support for Global Server Load Balancing (GSLB) is not yet available when using a custom agent ingress address, so you’ll need to specify the POP this agent should use to connect to the ngrok platform.

Add the following sections to the ngrok.yml config file, substituting the appropriate values for your environment, including a subdomain to connect to the agent api, such as agent.customer1.configurable-domain.com:

#config.yml

version: "2"
authtoken: { YOUR_AUTHTOKEN_WITH_ACL }
server_addr: { VALUE_FROM_REGION_DOMAINS }

tunnels:
  agent-api:
    proto: http
    domain: agent.customer1.{ YOUR_DOMAIN }
    addr: 4040
    inspect: false

Start the agent to access the agent API​

Now that you’ve updated the ngrok.yml config file, start the tunnel for the agent API by running the following command wherever you installed the agent:

ngrok start agent-api

Note that “agent-api” is the name given to the tunnel in the ngrok.yml example config file. You can use any descriptive name for this tunnel. In this case, you’re starting a tunnel to serve the ngrok agent API on https://agent.customer1.{YOUR_DOMAIN}.

If you wish to provide your customer with a custom ngrok.yml config file rather than modifying the one in the default location, as mentioned previously, you can pass the path to the file when you start the tunnel:

ngrok start agent-api –config /path/to/ngrok.yml

You can pass multiple paths to config files, and ngrok will merge them before starting.

Start tunnels in your customer’s network​

You now have the ngrok agent running in your customer's environment and can use the agent API to start and stop the tunnels necessary to access your customer’s APIs.

To start a tunnel to connect to your customer’s API, run the following command, substituting the appropriate values for your environment:

curl -H "Content-Type: application/json" \
-X POST https://agent.customer1.{YOUR_DOMAIN}/api/tunnels \
-d '{"name":"EXAMPLE","proto":"http", "addr":"{PORT}", "domain":"api.customer1.{YOUR_DOMAIN}"

The example below creates a tunnel on port 3000 and serves it at api.customer1.configurable-domain.com. Because a previous step created the wildcard domain on *.customer1.configurable-domain.com, a tunnel can be started on api.customer1.configurable-domain.com without reserving that subdomain.

curl -H "Content-Type: application/json" \
-X POST https://agent.customer1.configurable-domain.com/api/tunnels \
-d '{"name":"EXAMPLE","proto":"http", "addr":"3000", "domain":"api.customer1.configurable-domain.com",}'