Receiving webhooks in a private service by using Nebius Tunnels

Webhook providers such as GitHub, Stripe and Telegram send requests to publicly reachable HTTPS endpoints. A webhook handler running on a virtual machine (VM) without a public IP address cannot receive these requests directly. Nebius Tunnels provides a public HTTPS endpoint for the webhook handler. A tunnel agent running on the VM establishes an outbound connection to Nebius Tunnels. When a webhook provider sends a request to the public endpoint, Nebius Tunnels forwards it through this connection to the handler on the VM. The VM does not need an open inbound firewall port. The tunnel URL remains stable for the lifetime of the tunnel. You can configure this URL as the webhook endpoint in the external service and continue using the same URL for subsequent requests. When the VM starts, the tunnel agent starts automatically and connects to the tunnel. Requests sent to the public tunnel URL are forwarded through this connection to the service running on the VM.

Limitations

Before creating the infrastructure, consider the following:

Connect only one VM to each tunnel. Connecting multiple VMs to the same tunnel is not supported.
Nebius Tunnels forwards incoming requests but does not authenticate their senders. Configure your webhook handler to verify the signature provided by the webhook provider.

Costs

Nebius AI Cloud charges you for the following billing items:

Compute virtual machine
Boot disk attached to the VM

Nebius Tunnels is in preview and provided free of charge.

Steps

Create a tunnel

Web console
CLI

In the web console, select the project where you want to create the infrastructure. All resources must be located in the same project.
Go to Networking → Tunnels.
Click Create tunnel.
On the page that opens, set the tunnel name to my-tunnel.
Click Create tunnel.

Install and configure the Nebius AI Cloud CLI. When configuring the CLI profile, set the project where you want to create the infrastructure. All resources must be located in the same project. All nebius commands by default use the project ID from your CLI profile configuration.

Create a tunnel:

nebius tunnel create --title my-tunnel

Configure access for the tunnel agent

To authorize the VM in the tunnel, prepare a service account with the applicationtunnel.agent role. Later, you attach this service account to the VM.

Create the service account:
- Web console
- CLI
1. In the sidebar, go to Administration → IAM.
2. Click Create resource → Service account.
3. In the window that opens, set the name to tunnel-agent-sa and select the project.
4. Click Create and continue.
nebius iam service-account create --name tunnel-agent-sa
Create a custom group in Identity and Access Management to assign the role to the service account:
- Web console
- CLI
1. In the sidebar, go to Administration → IAM.
2. Click Create resource → Group.
3. In the window that opens, set the group name to tunnel-agents. In the Scope field, select the project where you create all the resources.
4. Click Create.
nebius iam group create --name tunnel-agents
Attach the tunnel and grant the applicationtunnel.agent role to this group. You can only grant this role by using the CLI.
- CLI
1. Get the group ID:
  nebius iam group list
  The ID is specified in the items.metadata.id parameter in the output.
2. Get the tunnel ID:
  nebius tunnel list
3. Create an access permit in the custom group:
  nebius iam access-permit create \ --parent-id <group_ID> \ --resource-id <tunnel_ID> \ --role applicationtunnel.agent
Add the service account to the group:
- Web console
- CLI
1. Go to Administration → IAM.
2. On the Groups tab, find and open the tunnel-agents group.
3. Click Add members.
4. In the window that opens, add the tunnel-agent-sa service account.
5. Once the account is added, close the window.
Check the group page in general. Make sure that:
- The tunnel-agent-sa service account is specified on the Members tab.
- The tunnel and the applicationtunnel.agent role are specified on the Access permits tab.
nebius iam group-membership create \ --parent-id <group_ID> \ --member-id <service_account_ID>
To get the service account ID, run:
nebius iam service-account list

Create a virtual machine

Create a VM without a public IP address and use a cloud-init configuration to install and start the tunnel agent and a sample webhook handler. Attach the service account you configured earlier so that the tunnel agent can connect to the tunnel.

If you need to change the VM configuration later, update webhook.yaml, delete the VM and create a new one. A tunnel should be associated with only one VM, and you can’t change the cloud-init configuration of an existing VM.

Generate an SSH key pair.

Prepare the cloud-init configuration file. You’ll attach it to the VM. In this file, specify two parameters:

users.ssh_authorized_keys: Public SSH key.
write_files.content.tunnel_id: ID of the tunnel.

webhook.yaml

#cloud-config
users:
  - name: ubuntu
    sudo: "ALL=(ALL) NOPASSWD:ALL"
    shell: /bin/bash
    ssh_authorized_keys:
      - <public_SSH_key>

# Driverless images don't include Docker, so install it during VM initialization.
package_update: true
packages:
  - docker.io

write_files:
  - path: /etc/nebius-tunnel-agent/config.yaml
    permissions: "0640"
    content: |
      tunnel_id: <tunnel_ID>

      iam:
        metadata:
          enabled: true

      logging:
        level: info
        format: json

      services:
        - name: hook
          type: http
          target: 127.0.0.1:8080
        - name: ssh
          type: tcp
          target: 127.0.0.1:22

  - path: /etc/systemd/system/nebius-tunnel-agent.service
    permissions: "0644"
    content: |
      [Unit]
      Description=Nebius tunnel agent
      Documentation=https://docs.nebius.com/tunnels
      After=network-online.target
      Wants=network-online.target

      [Service]
      Type=simple
      User=tunna
      Group=tunna
      ExecStart=/usr/local/bin/nebius-tunnel-agent --config /etc/nebius-tunnel-agent/config.yaml
      Restart=always
      RestartSec=5
      NoNewPrivileges=true
      ProtectSystem=strict
      ProtectHome=true
      PrivateTmp=true
      ReadOnlyPaths=/etc/nebius-tunnel-agent

      [Install]
      WantedBy=multi-user.target

  - path: /usr/local/sbin/install-nebius-tunnel-agent
    permissions: "0755"
    content: |
      #!/bin/bash
      set -euo pipefail

      VERSION="${AGENT_VERSION:-latest}"
      BASE="https://storage.eu-north1.nebius.cloud/products/releases/nebius-tunnel-agent"
      CONF_DIR=/etc/nebius-tunnel-agent

      case "$(uname -m)" in
        x86_64)        PLATFORM=linux-x86_64 ;;
        aarch64|arm64) PLATFORM=linux-aarch64 ;;
        *) echo "unsupported architecture: $(uname -m)" >&2; exit 1 ;;
      esac
      ASSET="nebius-tunnel-agent-${PLATFORM}.tar.gz"

      TMP="$(mktemp -d)"
      trap 'rm -rf "$TMP"' EXIT

      fetch() {
        curl -fsSL --retry 5 --retry-delay 3 --retry-connrefused -o "$2" "$1"
      }
      fetch "$BASE/$VERSION/$ASSET" "$TMP/$ASSET"
      fetch "$BASE/$VERSION/checksums-sha256.txt" "$TMP/checksums-sha256.txt"

      (cd "$TMP" && sha256sum --ignore-missing -c checksums-sha256.txt)

      tar -xzf "$TMP/$ASSET" -C "$TMP"
      install -m0755 "$TMP/nebius-tunnel-agent" /usr/local/bin/nebius-tunnel-agent

      getent group tunna >/dev/null || groupadd --system tunna
      id -u tunna >/dev/null 2>&1 || useradd --system --gid tunna \
        --no-create-home --shell /usr/sbin/nologin tunna
      chown -R tunna:tunna "$CONF_DIR"
      chmod 0750 "$CONF_DIR"
      chmod 0640 "$CONF_DIR/config.yaml"

      systemctl daemon-reload
      systemctl enable nebius-tunnel-agent.service
      systemctl restart nebius-tunnel-agent.service

  - path: /etc/systemd/system/webhook-sink.service
    permissions: "0644"
    content: |
      [Unit]
      Description=go-httpbin webhook sink (behind a Nebius tunnel)
      After=network-online.target docker.service
      Wants=network-online.target
      Requires=docker.service

      [Service]
      ExecStartPre=-/usr/bin/docker rm -f webhook-sink
      ExecStartPre=/usr/bin/docker pull ghcr.io/mccutchen/go-httpbin:2.22
      ExecStart=/usr/bin/docker run --rm --name webhook-sink \
        -p 127.0.0.1:8080:8080 \
        ghcr.io/mccutchen/go-httpbin:2.22
      ExecStop=/usr/bin/docker stop webhook-sink
      Restart=on-failure
      RestartSec=10
      TimeoutStartSec=0

      [Install]
      WantedBy=multi-user.target

runcmd:
  # Agent first: the tunnel is up while the backend is still pulling images.
  - [/usr/local/sbin/install-nebius-tunnel-agent]
  - systemctl enable --now webhook-sink.service

This configuration enables the following actions:

Add a username and a public SSH key to the VM.
Install Docker on the VM.
Authenticate by using the service account attached to the VM.
Create two Nebius Tunnels services:
- hook: To receive incoming webhook requests on port 8080.
- ssh: To connect to the VM by using SSH.
Deploy the tunnel agent on the VM.
Deploy go-httpbin as a placeholder webhook receiver. Replace it with your own service and point target at its port.

Create the VM:
- Web console
- CLI
1. In the sidebar, go to Compute → Virtual machines.
2. Click Create resource → Virtual machine. The creation flow is a step-by-step wizard. The sidebar shows your progress through the configuration sections. To move between sections, click Back and Next.
3. On the Compute step, configure computing resources:
  
  In the Platform section, select:
  
  Without GPUs
  
  Regular
  
  Non-GPU AMD Epyc Genoa
  
  In the Settings section, set:
  
  Preset: 2 CPUs - 8 GiB RAM.
  
  Project: The project where you create all resources for the tunnel.
  
  VM name: tunnel-hook.
4. On the Storage step, preserve the Ubuntu 24.04 LTS disk image and the SSD disk type, but change the disk size to 20 GiB.
5. On the Network step, check the network and subnet. Keep None in the Public IP address field.
6. On the Configuration step, configure the access, identity and VM startup settings:
  
  In the Service account field, select the tunnel-agent-sa service account.
  
  Enable a custom cloud-init configuration file.
  
  In the field that appears, paste the contents of the webhook.yaml file prepared earlier.
7. On the Review step, check the full VM configuration. To change a section quickly, click next to the corresponding block. The wizard opens the relevant step with your current settings.
8. Click Create VM.
nebius compute instance create \ --name tunnel-hook \ --resources-platform cpu-e2 \ --resources-preset 2vcpu-8gb \ --boot-disk-attach-mode READ_WRITE \ --boot-disk-managed-disk-name tunnel-hook-boot \ --boot-disk-managed-disk-type network_ssd \ --boot-disk-managed-disk-size-gibibytes 20 \ --boot-disk-managed-disk-source-image-family-image-family ubuntu24.04-driverless \ --network-interfaces "[{\"name\": \"eth0\", \"ip_address\": {}, \"subnet_id\": \"<subnet_ID>\"}]" \ --service-account-id <service_account_ID> \ --cloud-init-user-data "$(cat webhook.yaml)"
In the command, specify the subnet ID and the ID of the tunnel-agent-sa service account.

Wait for the VM to start running.

Check the result

The tunnel agent starts as soon as the VM boots. The webhook-sink service starts shortly after Docker pulls the go-httpbin image. To check that the webhook endpoint is working, send a test request from your local machine:

curl -X POST \
  https://hook-<tunnel_masked_ID>.tunnel.applications.<region>.nebius.cloud/anything \
  -H "Content-Type: application/json" \
  -d '{"ping": 1}'

In the URL, specify:

tunnel_masked_ID: Mask of the tunnel ID without the applicationtunnel- prefix and regional routing code. Contains the last 15 characters of the tunnel ID. For example, for applicationtunnel-e00abcdef123456789, the masked ID of the tunnel is abcdef123456789.
region: Region of the project where you created the resources.

For more information about the tunnel URL, see Supported traffic. The expected response is a JSON object that echoes back the request details:

{
  "method": "POST",
  "url": "https://hook-<tunnel_masked_ID>.tunnel.applications.<region>.nebius.cloud/anything",
  "data": "{\"ping\": 1}",
  ...
}

If the response is failed to connect to local service, the webhook-sink service hasn’t started yet. Wait a few moments and try again. If it still fails, see Troubleshooting. Once the endpoint is working, paste the tunnel URL — https://hook-<tunnel_masked_ID>.tunnel.applications.<region>.nebius.cloud — into the webhook settings of your provider (GitHub, Stripe, Telegram, etc.). The tunnel URL is stable for the tunnel’s lifetime, so you only need to do this once. To replace go-httpbin with your own webhook handler, update webhook.yaml, delete the VM and create it again. Configure your handler to listen on port 8080, or change the tunnel agent’s target to match your handler’s port.

Troubleshooting

If the test request fails, or the tunnel returns failed to connect to local service, connect to the VM and check the tunnel agent and the webhook handler. The VM has no public IP address. Connect through the ssh service of the tunnel.

Connect to the VM

Connect to the VM as described in Connecting to a virtual machine without a public IP address. If you still can’t open the session, use the serial console and run the checks below from there.

Check the tunnel agent

On the VM, check the agent service and its logs:

sudo systemctl status nebius-tunnel-agent.service
sudo journalctl -u nebius-tunnel-agent.service

Add -f to follow new log lines, for example sudo journalctl -u nebius-tunnel-agent.service -f. When the agent has registered with the tunnel, the logs include the public endpoint of each service. If the agent doesn’t register, check for these common causes:

The VM has no service account attached. systemctl status still shows active (running), but the agent retries indefinitely, showing IMDS token request failed: 404 Not Found followed by connection closed before registering. You can’t attach a service account to an existing VM. Delete the VM and create a new one with the tunnel-agent-sa service account attached.
The tunnel agent isn’t authorized to connect to the tunnel. Verify that the tunnel-agent-sa service account belongs to the tunnel-agents group and that the group includes the applicationtunnel.agent role for this tunnel. Check the steps in Configure access for the tunnel agent.

Check that tunnel_id in the agent configuration is the ID of the tunnel you created:

sudo grep tunnel_id /etc/nebius-tunnel-agent/config.yaml

The value looks like applicationtunnel-e00abcdef123456789. If it is still the <tunnel_ID> placeholder, or it points at a different tunnel, delete the VM and create it again with the correct tunnel ID in webhook.yaml.

Check the webhook handler

The hook service forwards requests to webhook-sink on port 8080. Check that service and its logs:

sudo systemctl status webhook-sink.service
sudo journalctl -u webhook-sink.service

webhook-sink runs go-httpbin in Docker. If the unit is active and requests still fail, check the container:

sudo docker ps -a --filter name=webhook-sink
sudo docker logs webhook-sink

The first command should return a container named webhook-sink. Its status should begin with Up, and the port mapping should be 127.0.0.1:8080->8080/tcp. This means that the container is running and its port 8080 is available through the VM’s loopback interface. The output of the second command should contain the following message:

go-httpbin listening on http://0.0.0.0:8080

Check cloud-init

Use this check if either systemctl status command reports that the nebius-tunnel-agent.service or webhook-sink.service unit could not be found. This means that cloud-init might not have completed successfully. Check the cloud-init output:

sudo tail -n 200 /var/log/cloud-init-output.log

The log records the installation of the tunnel agent and the startup of webhook-sink.service. Check it for errors related to downloading or installing the tunnel agent, installing Docker or starting the webhook handler. After resolving the error, delete the VM and create it again with the corrected webhook.yaml file because cloud-init runs only when the VM is created.

How to delete the created resources

The created VM and its boot disk are chargeable. If you don’t need them, delete the VM, so Nebius AI Cloud doesn’t charge for the resources. The boot disk is deleted automatically when you delete the VM. You can also delete free resources:

​Limitations

​Costs

​Steps

​Create a tunnel

​Configure access for the tunnel agent

​Create a virtual machine

​Check the result

​Troubleshooting

​Connect to the VM

​Check the tunnel agent

​Check the webhook handler

​Check cloud-init

​How to delete the created resources

Limitations

Costs

Steps

Create a tunnel

Configure access for the tunnel agent

Create a virtual machine

Check the result

Troubleshooting

Connect to the VM

Check the tunnel agent

Check the webhook handler

Check cloud-init

How to delete the created resources