:lastproofread: 2022-08-24

.. _cloud-init:

###############
VyOS cloud-init
###############

Cloud and virtualized 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.

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Config Sources
**************

VyOS support three types 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 - This config source informs the system about the
  network settings like IP addresses, routes, DNS. Available only in several
  cloud and virtualization platforms.
* User-data - User-data is specified by the user. This config source offers the
  ability to insert any CLI configuration commands into the configuration before
  the first boot.

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User-data
*********

Major cloud providers offer a means of providing user-data at the time of
instance launch. It can be provided as plain text or as base64-encoded text,
depending on cloud provider. Also, it can be compressed using gzip, which makes
sense with a long configuration commands list, because of the hard limit to
~16384 bytes for the whole user-data.

The easiest way to configure the system via user-data is the Cloud-config syntax
described below.

********************
Cloud-config modules
********************

In VyOS, by default, enabled only two modules:

* ``write_files`` - this module allows to insert any files into the filesystem
  before the first boot, for example, pre-generated encryption keys,
  certificates, or even a whole ``config.boot`` file.
* ``vyos_userdata`` - the module accepts a list of CLI configuration commands in
  a ``vyos_config_commands`` section, which gives an easy way to configure the
  system during deployment.

************************
cloud-config file format
************************

A cloud-config document is written in YAML. The file must begin
with ``#cloud-config`` line. 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 overwrites default
configuration values and values configured via Metadata.

Here is an example cloud-config.

.. code-block:: yaml

   #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 '192.0.2.247/24'
     - set protocols static route 198.51.100.0/24 next-hop '192.0.2.1'

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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 the configuration in user-data.

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Troubleshooting
***************

If you encounter problems, verify that the cloud-config document contains
valid YAML. Online resources such as https://www.yamllint.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. You can fetch the
most important data filtering output for ``vyos`` keyword:

.. code-block:: none

    sudo grep vyos /var/log/cloud-init.log