Cloud-Init

Overview

Cloud-init is an industry-standard tool for automating the initial configuration of virtual machines on first boot. NVIDIA Air supports cloud-init through the NoCloud datasource, which allows you to inject user-data and meta-data into your simulation nodes.

With cloud-init, you can automate tasks such as:

• Setting hostnames
• Installing packages
• Writing configuration files
• Running custom scripts on first boot

Supported Images

Cloud-init works on any image that includes cloud-init with NoCloud datasource support, including custom images. The Air-provided generic/ubuntu images include cloud-init out of the box.

Configuration

Cloud-init configuration consists of two components:

• User-data: Defines the actions to perform on first boot, such as installing packages, running commands, or writing files. Supports all standard cloud-init user-data formats.
• Meta-data: Provides instance metadata such as the hostname. Uses a simple key: value format.

Workflow

Cloud-init is configured through the API. The general workflow is:

1. Create a simulation with your desired topology, but do not start it yet.
2. Create UserConfig resources containing your user-data and meta-data content. UserConfigs are reusable — for example, you can create one user-data config and share it across multiple nodes, while giving each node its own meta-data with a unique hostname.
3. Assign the UserConfig resources to simulation nodes using the bulk-assign endpoint. This endpoint lets you assign both user-data and meta-data to multiple nodes in a single request.
4. Start the simulation. Cloud-init runs automatically on each node during its first boot.

Example

The following cloud-config user-data installs packages and writes a configuration file on first boot:

#cloud-config

packages:
- curl
- jq

write_files:
- path: /etc/myapp/config.yaml
  content: |
    server:
      listen: 0.0.0.0:8080
      log_level: info

For information and additional examples of user-data and meta-data formats, refer to the cloud-init documentation.