cloudinit

Documentation

Overview

Package cloudinit is a simple approach to generate a cloud-config file for cloud-init. To avoid bringing in a YAML library, it exploits the fact that YAML is a superset of JSON, so any JSON object is valid YAML.

Index

• type CloudConfig
  • func (cfg CloudConfig) Render() ([]byte, error)
• type WriteFile

Types

type CloudConfig

type CloudConfig struct {
	// Run arbitrary commands at a rc.local-like time-frame with output to the
	// console. The items will be executed as if passed to execve(3) (with the
	// first argument as the command). The 'runcmd' module only writes the
	// script to be run later. The module that actually runs the script is
	// 'scripts_user' in the Final boot stage.
	// https://cloudinit.readthedocs.io/en/latest/reference/modules.html#runcmd
	RunCmd []string `json:"runcmd,omitzero"`

	//
	// SSH
	// https://cloudinit.readthedocs.io/en/latest/reference/modules.html#ssh
	//
	// Remove host SSH keys. This prevents re-use of a private host key from an
	// image with default host SSH keys. Default: true.
	SshDeleteKeys bool `json:"ssh_deletekeys,omitzero"`
	// The SSH key types to generate. Default: [rsa, ecdsa, ed25519].
	SshGenKeyTypes []string `json:"ssh_genkeytypes,omitzero"`

	// Write arbitrary files.
	// https://cloudinit.readthedocs.io/en/latest/reference/modules.html#write-files
	WriteFiles []WriteFile `json:"write_files,omitzero"`
}

CloudConfig represents the cloud-config file. Fill the fields that you need and call CloudConfig.Render.

The field names and descriptions are from the cloud-config documentation 1. Note that all the unfilled fields will have the default value specified by the cloud-config documentation 1, not their Go zero value (for example, it is possible that a boolean field gets true as default value. Read the field documentation in case of doubt).

Only the subset of fields that I need are available. Additional fields from upstream could be added.

To aid in debugging, cloud-init logs everything to /var/log/cloud-init-output.log, including the output of [CloudConfig.RunCmd].

func (CloudConfig) Render

func (cfg CloudConfig) Render() ([]byte, error)

Render returns the cloud-config object as JSON (which is valid YAML).

NOTE The output of Render can still be an invalid cloud-config file, exactly as you could write by hand a syntactically valid YAML file that is an invalid cloud-config file.

type WriteFile

type WriteFile struct {
	// Path of the file to which Content is decoded and written.
	Path string `json:"path"`
	// Optional content to write to the provided Path. When content is present
	// and encoding is not ‘text/plain’, decode the content prior to writing.
	Content string `json:"content,omitzero"`
	//  Optional owner:group to chown on the file and new directories. Default:
	//  root:root.
	Owner string `json:"owner,omitzero"`
	// Optional file permissions to set on Path represented as an octal string
	// ‘0###’. Default: 0o644.
	Permissions string `json:"permissions,omitzero"`
	// Optional encoding type of the content. Default: text/plain. Supported
	// encoding types are: gz, gzip, gz+base64, gzip+base64, gz+b64, gzip+b64,
	// b64, base64.
	Encoding string `json:"encoding,omitzero"`
}

Write a file. https://cloudinit.readthedocs.io/en/latest/reference/modules.html#write-files