Hetzner-Traffic-Manager

This script monitors the outgoing traffic of a Hetzner Cloud server. If the outgoing traffic exceeds a set limit, the server will be shut down. It uses the Hetzner Cloud API.

Prerequisites

1. Hetzner Cloud API Token: You need an API token from your Hetzner Cloud account. You can generate one from Hetzner Cloud Console (Guide).
2. jq: A command-line JSON processor used to parse API responses.

Installation

1. Install the necessary packages, if not already done:

   sudo apt update -y
   sudo apt-get install jq -y

2. Download the script:

   wget https://raw.githubusercontent.com/JanisPlayer/Hetzner-Traffic-Manager/refs/heads/main/hetzner_traffic_manager.sh
   sudo chmod 700 ./hetzner_traffic_manager.sh
   sudo chown -R root:root ./hetzner_traffic_manager.sh

3. Configure the script

• Open hetzner_traffic_manager.sh and add your Hetzner API token and server ID in the configuration section:

  API_TOKEN="your-api-token"        # Your Hetzner Cloud API token
  SERVER_ID="your-server-id"        # The ID of the server to monitor
  LIMIT_TB_OFFSET=-1                # Adjusts the included traffic down (-1) or up (+1) in TB
  LIMIT_GB_OFFSET=0                 # Fine-tune the traffic limit in GB (can adjust the value of LIMIT_TB_OFFSET)

  Note: Ensure there is a sufficient buffer from the traffic limit because the Hetzner API does not update the total outgoing traffic in real-time. This delay can lead to inaccuracies if the buffer is too small. The delay is as in the dashboard, about 1 hour.
  The values of LIMIT_TB_OFFSET and LIMIT_GB_OFFSET are used together to calculate the LIMIT_BYTES_OFFSET.
  Additionally, Bash natively does not support floating-point calculations without additional libraries or tools. Therefore, TB values derived from the calculated byte offset cannot be fully trusted for precise console output. Manually verify the conversion from bytes to TB when using the GB offset to ensure accuracy.

Usage

1. Run the script to test:

   After adjusting the configuration, you can run the script directly to test it:

   /root/hetzner_traffic_manager.sh

2. Automate with Cron:

   You can run the script regularly using Cron. Add it to your Crontab:

   sudo crontab -e

   Example: Run every minute:

   * * * * * /root/hetzner_traffic_manager.sh

   Alternative way to add via a temporary file:

   crontab -u root -l > /tmp/tmp_crontab && echo "* * * * * /root/hetzner_traffic_manager.sh" >> /tmp/tmp_crontab
   crontab -u root /tmp/tmp_crontab && rm /tmp/tmp_crontab
   

Possible Improvements:

• Manage multiple servers returned by the API query and match them based on their IDs.
• Apply the offset limit for each server individually, allowing for more flexible traffic monitoring across multiple servers.
• Better handling of API errors.

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⚠ Known Issue – Hetzner API Traffic Reporting at Start of Month

At the beginning of each month, the Hetzner Cloud API may temporarily return (usually a few hours to a couple of days):

server.included_traffic = 0

During this time, traffic values such as 0 / 0 TB may be reported. This can cause the script to incorrectly assume that the traffic limit has been reached and shut down the server.

Workaround

To prevent accidental shutdowns, the script now skips the shutdown check if server.included_traffic is: empty, null, 0.
This ensures the server will not be shut down due to invalid API responses.
During this period, traffic monitoring is effectively paused because the reported values cannot be trusted.
If strict enforcement is required, consider monitoring traffic directly on the server or implementing additional validation logic.
This issue was reported to Hetzner support (February 2026) by @matburnham: #1 (comment)