VyOS cloud-init

Cloud instances of VyOS are initialized using the industry-standard cloud-init. Via cloud-init, the system performs tasks such as injecting SSH keys and configuring the network. In addition, the user can supply a custom configuration at the time of instance launch.

Config Sources

VyOS support three type of config sources.

  • Metadata - Metadata is sourced by the cloud platform or hypervisor. In some clouds, there is implemented as an HTTP endpoint at http://169.254.169.254.
  • Network configuration - Ths config source informs the system about the network.
  • User-data - User-data is specified by the user. This config source offers the most flexibility and will be the focus of this documentation.

User-data

Major cloud providers offer a means of providing user-data at the time of instance launch. Typically the user includes user-data as plain text and the cloud provider’s platform base64 encodes the user-data before injecting it into the instance.

VyOS implements a user-data format called cloud-config.

cloud-config file format

A cloud-config document is written in YAML. The file must begin with “#cloud-config”. The key used to designate a VyOS configuration is “vyos_config_commands”. What follows is VyOS configuration using the “set-style” syntax. Both “set” and “delete” commands are supported.

Commands requirements:

  • one command per line
  • if command ends in a value, it must be inside single quotes
  • a single-quote symbol is not allowed inside command or value

The commands list produced by the show configuration commands command on a VyOS router should comply with all the requirements, so it is easy to get a proper commands list by copying it from another router.

The configuration specified in the cloud-config document is merged with the default configuration and saved to /config/config.boot.

Here is an example cloud-config.

#cloud-config
vyos_config_commands:
  - set system host-name 'vyos-prod-ashburn'
  - set system ntp server 1.pool.ntp.org
  - set system ntp server 2.pool.ntp.org
  - delete interfaces ethernet eth1 address 'dhcp'
  - set interfaces ethernet eth1 address '172.31.7.247/20'
  - set protocols static route '172.31.0.0/16' next-hop '100.64.16.1'

System Defaults/Fallbacks

These are the VyOS defaults and fallbacks.

  • SSH is configured on port 22
  • vyos/vyos credentials if no others specified by data source
  • DHCP on first Ethernet interface if no network configuration is provided

All of these can be overridden using configuration in user-data.

Troubleshooting

If you encounter problems, verify that the cloud-config document contains valid YAML. Online resources such as https://yamlvalidator.com/ provide a simple tool for validating YAML.

cloud-init logs to /var/log/cloud-init.log. This file can be helpful in determining why the configuration varies from what you expect.