• Setting a default locale
  • Setting an instance hostname
  • Generating instance SSH private keys
  • Adding SSH keys to a user’s .ssh/authorized_keys so they can log in
  • Setting up ephemeral mount points
  • Configuring network devices

User configurability

Cloud-init ‘s behavior can be configured via user-data.

User-data can be given by the user at instance launch time.

This is done via the --user-data or --user-data-file argument to ec2-run-instances for example.

  • Check your local clients documentation for how to provide a user-data string or user-data file for usage by cloud-init on instance creation.

Feature detection

Newer versions of cloud-init may have a list of additional features that they support. This allows other applications to detect what features the installed cloud-init supports without having to parse its version number. If present, this list of features will be located at cloudinit.version.FEATURES.

Currently defined feature names include:

CLI Interface

The command line documentation is accessible on any cloud-init installed system:

% cloud-init --help
usage: cloud-init [-h] [--version] [--file FILES]

                  [--debug] [--force]

optional arguments:
  -h, --help            show this help message and exit
  --version, -v         show program's version number and exit
  --file FILES, -f FILES
                        additional yaml configuration files to use
  --debug, -d           show additional pre-action logging (default: False)
  --force               force running even if no datasource is found (use at
                        your own risk)

    init                initializes cloud-init and performs initial modules
    modules             activates modules using a given configuration key
    single              run a single module
    dhclient-hook       run the dhclient hookto record network info
    features            list defined features
    analyze             Devel tool: Analyze cloud-init logs and data
    devel               Run development tools
    collect-logs        Collect and tar all cloud-init debug info
    clean               Remove logs and artifacts so cloud-init can re-run.
    status              Report cloud-init status or wait on completion.

CLI Subcommand details

cloud-init features

Print out each feature supported. If cloud-init does not have the features subcommand, it also does not support any features described in this document.

% cloud-init features

cloud-init status

Report whether cloud-init is running, done, disabled or errored. Exits non-zero if an error is detected in cloud-init.

  • –long: Detailed status information.
  • –wait: Block until cloud-init completes.
% cloud-init status --long
status: done
time: Wed, 17 Jan 2018 20:41:59 +0000
DataSourceNoCloud [seed=/var/lib/cloud/seed/nocloud-net][dsmode=net]

# Cloud-init running still short versus long options
% cloud-init status
status: running
% cloud-init status --long
status: running
time: Fri, 26 Jan 2018 21:39:43 +0000
Running in stage: init-local

cloud-init collect-logs

Collect and tar cloud-init generated logs, data files and system information for triage. This subcommand is integrated with apport.

Note: Ubuntu users can file bugs with ubuntu-bug cloud-init to automaticaly attach these logs to a bug report.

Logs collected are:

  • /var/log/cloud-init*log
  • /run/cloud-init
  • cloud-init package version
  • dmesg output
  • journalctl output
  • /var/lib/cloud/instance/user-data.txt

cloud-init analyze

Get detailed reports of where cloud-init spends most of its time. See Boot Time Analysis - cloud-init analyze for more info.

  • blame Report ordered by most costly operations.
  • dump Machine-readable JSON dump of all cloud-init tracked events.
  • show show time-ordered report of the cost of operations during each boot stage.

cloud-init devel

Collection of development tools under active development. These tools will likely be promoted to top-level subcommands when stable.

  • cloud-init devel schema: A #cloud-config format and schema validator. It accepts a cloud-config yaml file and annotates potential schema errors locally without the need for deployment. Schema validation is work in progress and supports a subset of cloud-config modules.

cloud-init clean

Remove cloud-init artifacts from /var/lib/cloud and optionally reboot the machine to so cloud-init re-runs all stages as it did on first boot.

  • –logs: Optionally remove /var/log/cloud-init*log files.
  • –reboot: Reboot the system after removing artifacts.

cloud-init init

Generally run by OS init systems to execute cloud-init’s stages init and init-local. See Boot Stages for more info. Can be run on the commandline, but is generally gated to run only once due to semaphores in /var/lib/cloud/instance/sem/ and /var/lib/cloud/sem.

  • –local: Run init-local stage instead of init.

cloud-init modules

Generally run by OS init systems to execute modules:config and modules:final boot stages. This executes cloud config Modules configured to run in the init, config and final stages. The modules are declared to run in various boot stages in the file /etc/cloud/cloud.cfg under keys cloud_init_modules, cloud_init_modules and cloud_init_modules. Can be run on the commandline, but each module is gated to run only once due to semaphores in /var/lib/cloud/.

  • –mode (init|config|final): Run modules:init, modules:config or modules:final cloud-init stages. See Boot Stages for more info.

cloud-init single

Attempt to run a single named cloud config module. The following example re-runs the cc_set_hostname module ignoring the module default frequency of once-per-instance:

  • –name: The cloud-config module name to run
  • –frequency: Optionally override the declared module frequency with one of (always|once-per-instance|once)
% cloud-init single --name set_hostname --frequency always

Note: Mileage may vary trying to re-run each cloud-config module, as some are not idempotent.