Configuring and Managing cloud-init for RHEL 8

Red Hat Enterprise Linux 8

Using cloud-init to automate the initialization of cloud instances

Red Hat Customer Content Services

Abstract

You can use cloud-init to automate the initialization of cloud instances.
You can install the cloud-init package on your virtual machine, or you can choose a Red Hat Enterprise Linux image that includes cloud-init already installed.
You can use cloud-init with a number of Red Hat products.

Making open source more inclusive

Red Hat is committed to replacing problematic language in our code, documentation, and web properties. We are beginning with these four terms: master, slave, blacklist, and whitelist. Because of the enormity of this endeavor, these changes will be implemented gradually over several upcoming releases. For more details, see our CTO Chris Wright’s message.

Providing feedback on Red Hat documentation

We appreciate your input on our documentation. Please let us know how we could make it better. To do so:

  • For simple comments on specific passages:

    1. Make sure you are viewing the documentation in the Multi-page HTML format. In addition, ensure you see the Feedback button in the upper right corner of the document.
    2. Use your mouse cursor to highlight the part of text that you want to comment on.
    3. Click the Add Feedback pop-up that appears below the highlighted text.
    4. Follow the displayed instructions.
  • For submitting more complex feedback, create a Bugzilla ticket:

    1. Go to the Bugzilla website.
    2. As the Component, use Documentation.
    3. Fill in the Description field with your suggestion for improvement. Include a link to the relevant part(s) of documentation.
    4. Click Submit Bug.

Chapter 1. Introduction to cloud-init

cloud-init is a software package that automates the initialization of cloud instances during system boot. You can configure cloud-init to perform a variety of tasks. Some sample tasks that cloud-init can perform include:

  • Configuring a host name
  • Installing packages on an instance
  • Running scripts
  • Suppressing default virtual machine behavior

Where you obtain your image for configuring cloud-init depends on how you intend to use it.

  • The cloud-init package is installed on KVM Guest Images that you download from the Red Hat Customer Portal. When you launch an instance, cloud-init is enabled. KVM Guest Images that you download from the Red Hat Customer Portal are intended for used with Red Hat Virtualization (RHV) and the Red Hat OpenStack Platform (RHOSP). You can also create an image from scratch for RHV and RHOSP.
  • Another option is to download an ISO image from the Red Hat Customer Portal or create one. In this case, you need to install cloud-init on your ISO image.
  • If you plan to use an image with a cloud provider (for example, AWS or Azure), use Red Hat Image Builder to create the image. Image Builder images are customized for use for specific cloud providers. The image types AMI, VHD, and qcow2 include cloud-init already installed. Refer to Composing a Customized RHEL System Image for information on Image Builder.

Most cloud platforms support cloud-init, though configuration procedures and supported options vary. Alternatively, you can configure cloud-init for a NoCloud environment.

You can configure cloud-init on one virtual machine (VM) and then use that VM as a template for additional VMs or clusters of VMs.

Specific Red Hat products (for example, Red Hat Virtualization) have documented procedures for configuring cloud-init for use with those products.

This document refers to the cloud-init documentation in a number of places. Refer to the referenced cloud-init documentation for complete information on cloud-init.

Prerequisites

Additional resources

1.1. cloud-init configuration

cloud-init uses YAML-formatted file instructions to perform tasks. You decide the initial configuration you want cloud-init to perform by providing instructions within the YAML files. When an instance boots, the cloud-init service starts and searches for and executes the instructions. Tasks complete during the first boot or on subsequent boots of your VM, based on your cloud-init configuration.

You define the tasks by configuring the /etc/cloud/cloud.cfg file and adding directives under the /etc/cloud/cloud.cfg.d/ directory.

  • The cloud.cfg file includes directives, such as those for user access and authentication and system information.

    The file also includes default and optional modules for cloud-init. The modules are executed in order within three phases that include the cloud-init initialization phase, the configuration phase, and the final phase. Within the cloud.cfg file, modules for the three phases are listed under cloud_init_modules, cloud_config_modules, and cloud_final_modules, respectively.

  • The cloud.cfg.d directory is where you can add additional directives for cloud-init. When you add directives to the cloud.cfg.d directory, you typically add them to a file named *.cfg, and you always include #cloud-config at the top of the file.

1.2. cloud-init operates in stages

cloud-init operates in five stages during a system boot. Those stages determine whether cloud-init runs and where it finds its datasources, among other tasks. A brief summary of the stages follows.

  1. The cloud-init generator stage, through the systemd service, determines whether to run cloud-init upon the boot.
  2. During the local stage, cloud-init finds local datasources and applies network configuration.
  3. During the network stage, cloud-init processes user data and runs the modules listed under cloud_init_modules in your cloud.cfg file. You can enable, disable, or add modules to the cloud_init_modules section.
  4. During the config stage, cloud-init runs the modules listed under cloud_config_modules in your cloud.cfg file. You can enable, disable, or add modules to the cloud_config_modules section.
  5. During the final stage, cloud-init can run what you have included under cloud_final_modules in your cloud.cfg file. You can include package installations that you would typically run after a system boots and can also include configuration management plug-ins and user scripts. You can enable, disable, or add modules to the cloud_final_modules section.

The five boot stages are described in the cloud-init Documentation section Boot Stages.

1.3. cloud-init modules execute in phases

When cloud-init runs, it executes the modules within cloud.cfg in order within three phases that include the network phase (cloud_init_modules), the configuration phase (cloud_config_modules), and the final phase (cloud_final_modules). When cloud-init runs for the first time on a VM, all the modules you have configured run in their respective phases. On a subsequent running of cloud-init, whether a module runs within a phase depends on the module frequency of the individual module. Some modules run every time cloud-init runs; some modules only run the first time cloud-init runs, even if the instance ID changes.

Note

An instance ID uniquely identifies an instance. When an instance ID changes, cloud-init treats the instance as a new instance.

A brief description of the module frequency values follows.

  • Per instance means that the module runs on first boot of an instance. For example, if you clone an instance or create a new instance from a saved image, the modules designated as per instance run again.
  • Per once means that the module runs only once. For example, if you clone an instance or create a new instance from a saved image, the modules designated per once do not run again on those instances.
  • Per always means the module runs on every boot.
Note

You can override a module’s frequency when you configure the module or by using the command line.

1.4. cloud-init acts upon user data, metadata, and vendor data

cloud-init consumes and acts upon user data, metadata, and vendor data.

  • User data includes directives you specify in the cloud.cfg file and in the cloud.cfg.d directory, for example, user data can include files to run, packages to install, and shell scripts. Refer to the cloud-init Documentation section User-Data Formats for information on the types of user data that cloud-init allows.
  • Metadata includes data associated with a specific datasource, for example, metadata can include a server name and instance ID. If you are using a specific cloud platform, the platform determines where your instances find user data and metadata. Your platform may require that you add metadata and user data to an HTTP service; in this case, when cloud-init runs it consumes metadata and user data from the HTTP service.
  • Vendor data is optionally provided by the organization (for example, a cloud provider) and includes information that can customize the image to better fit the environment where the image runs. cloud-init acts upon optional vendor data and user data after it reads any metadata and initializes the system. By default, vendor data runs on the first boot. You can disable vendor data execution.

    Refer to the cloud-init Documentation section Instance Metadata for a description of metadata; Datasources for a list of datasources; and Vendor Data for more information on vendor data.

1.5. cloud-init identifies the cloud platform

cloud-init attempts to identify the cloud platform using the script ds-identify. The script runs on the first boot of an instance.

Adding a datasource directive can save time when cloud-init runs. You would add the directive in the /etc/cloud/cloud.cfg file or in the /etc/cloud/cloud.cfg.d directory. A sample follows.

datasource_list:[Ec2]

Beyond adding the directive for your cloud platform, you can further configure cloud-init by adding additional configuration details, such as metadata URLs.

datasource_list: [Ec2]
datasource:
  Ec2:
    metadata_urls: ['http://169.254.169.254']

After cloud-init runs, you can view a log file (run/cloud-init/ds-identify.log) that provides detailed information about the platform.

Chapter 2. Red Hat support for cloud-init

This chapter covers Red Hat support for cloud-init. It includes information on Red Hat products that use cloud-init, cloud-init modules that Red Hat supports, and default directories and files.

2.1. cloud-init significant directories and files

The following table includes important directories and files. Review these directories and files; they allow you to perform tasks like:

  • Configuring cloud-init
  • Finding information on your configuration after cloud-init has run
  • Examining log files
  • Finding templates

Depending on your scenario and datasource, there can be additional files and directories important to your configuration.

Table 2.1. cloud-init directories and files

Directory or FileDescription

/etc/cloud/cloud.cfg

The cloud.cfg file includes the basic cloud-init configuration and lets you know in what phase each module runs.

/etc/cloud/cloud.cfg.d

The cloud.cfg.d directory is where you can add additional directives for cloud-init.

/var/lib/cloud

When cloud-init runs, it creates a directory layout under /var/lib/cloud. The layout includes directories and files that give specifics on your instance configuration.

/usr/share/doc/cloud-init/examples

The examples directory includes multiple examples. You can use them to help model your own directives.

/etc/cloud/templates

This directory includes templates that you can enable in cloud-init for certain scenarios. The templates provide direction for enabling.

/var/log/cloud-init.log

The cloud-init.log file provides log information helpful for debugging.

/run/cloud-init

The /run/cloud-init directory includes logged information on your datasource and the ds-identify script.

2.2. Red Hat products that use cloud-init

You can use cloud-init with the following Red Hat products.

2.3. Red Hat supports these cloud-init modules

Red Hat supports most cloud-init modules. Individual modules can contain multiple configuration options. The following table lists all of the cloud-init modules that Red Hat currently supports and provides a brief description and the default module frequency. Refer to Modules in the cloud-init Documentation section for complete descriptions and options for these modules.

Table 2.2. Supported cloud-init modules

cloud-init ModuleDescriptionDefault Module Frequency

bootcmd

Runs commands early in the boot process

per always

ca_certs

Adds CA certificates

per instance

debug

Enables or disables output of internal information to assist with debugging

per instance

disable_ec2_metadata

Enables or disables the AWS EC2 metadata

per always

disk_setup

Configures simple partition tables and file systems

per instance

final_message

Specifies the output message once cloud-init completes

per always

foo

Example shows module structure (Module does nothing)

per instance

growpart

Resizes partitions to fill the available disk space

per always

keys_to_console

Allows controls of fingerprints and keys that can be written to the console

per instance

landscape

Installs and configures a landscape client

per instance

locale

Configures the system locale and applies it system-wide

per instance

mcollective

Installs, configures, and starts mcollective

per instance

migrator

Moves old versions of cloud-init to newer versions

per always

mounts

Configures mount points and swap files

per instance

phone_home

Posts data to a remote host after boot completes

per instance

power_state_change

Completes shutdown and reboot after all configuration modules have run

per instance

puppet

Installs and configures puppet

per instance

resizefs

Resizes a file system to use all available space on a partition

per always

resolve_conf

Configures resolv.conf

per instance

rh_subscription

Registers a Red Hat Enterprise Linux system

per instance

rightscale_userdata

Adds support for RightScale configuration hooks to cloud-init

per instance

rsyslog

Configures remote system logging using rsyslog

per instance

runcmd

Runs arbitrary commands

per instance

salt_minion

Installs, configures, and starts salt minion

per instance

scripts_per_boot

Runs per boot scripts

per always

scripts_per_instance

Runs per instance scripts

per instance

scripts_per_once

Runs scripts once

per once

scripts_user

Runs user scripts

per instance

scripts_vendor

Runs vendor scripts

per instance

seed_random

Provides random seed data

per instance

set_hostname

Sets host name and fully qualified domain name (FQDN)

per always

set_passwords

Sets user passwords and enables or disables SSH password authentication

per instance

ssh_authkey_fingerprints

Logs fingerprints of user SSH keys

per instance

ssh_import_id

Imports SSH keys

per instance

ssh

Configures SSH, and host and authorized SSH keys

per instance

timezone

Sets the system time zone

per instance

update_etc_hosts

Updates /etc/hosts

per always

update_hostname

Updates host name and FQDN

per always

users_groups

Configures users and groups

per instance

write_files

Writes arbitrary files

per instance

yum_add_repo

Adds yum repository configuration to the system

per always

The following table lists modules that Red Hat does not currently support.

Table 2.3. Modules not supported

Module

apt_configure

apt_pipeline

byobu

chef

emit_upstart

grub_dpkg

ubuntu_init_switch

2.4. The default cloud.cfg file

The /etc/cloud/cloud.cfg file lists the modules comprising the basic configuration for cloud-init.

The modules in the file are the default modules for cloud-init. You can configure the modules for your environment or remove modules you do not need. Modules that are included in cloud.cfg do not necessarily do anything by being listed in the file. You need to configure them individually if you want them to perform actions during one of the cloud-init phases.

The cloud.cfg file provides the chronology for running individual modules. You can add additional modules to cloud.cfg as long as Red Hat supports the modules you want to add.

What follows are the default contents of the file for Red Hat Enterprise Linux (RHEL).

Note
  • Modules run in the order given in cloud.cfg. You typically do not change this order.
  • The cloud.cfg directives can be overridden by user data.
  • When running cloud-init manually, you can override cloud.cfg with command line options.
  • Each module includes its own configuration options, where you can add specific information.
users: 1
 - default

disable_root: 1 2
ssh_pwauth:   0 3

mount_default_fields: [~, ~, 'auto', 'defaults,nofail,x-systemd.requires=cloud-init.service', '0', '2'] 4
ssh_deletekeys:   1 5
ssh_genkeytypes:  ~ 6
syslog_fix_perms: ~ 7
disable_vmware_customization: false 8

cloud_init_modules: 9
 - disk_setup
 - migrator
 - bootcmd
 - write-files
 - growpart
 - resizefs
 - set_hostname
 - update_hostname
 - update_etc_hosts
 - rsyslog
 - users-groups
 - ssh

cloud_config_modules: 10
 - mounts
 - locale
 - set-passwords
 - rh_subscription
 - yum-add-repo
 - package-update-upgrade-install
 - timezone
 - puppet
 - chef
 - salt-minion
 - mcollective
 - disable-ec2-metadata
 - runcmd

cloud_final_modules: 11
 - rightscale_userdata
 - scripts-per-once
 - scripts-per-boot
 - scripts-per-instance
 - scripts-user
 - ssh-authkey-fingerprints
 - keys-to-console
 - phone-home
 - final-message
 - power-state-change

system_info:
  default_user: 12
    name: cloud-user
    lock_passwd: true
    gecos: Cloud User
    groups: [adm, systemd-journal]
    sudo: ["ALL=(ALL) NOPASSWD:ALL"]
    shell: /bin/bash
  distro: rhel 13
  paths:
    cloud_dir: /var/lib/cloud 14
    templates_dir: /etc/cloud/templates 15
  ssh_svcname: sshd 16

# vim:syntax=yaml
1
Specifies the default user for the system. Refer to Users and Groups for more information.
2
Enables or disables root login. Refer to Authorized Keys for more information.
3
Specifies whether ssh is configured to accept password authentication. Refer to Set Passwords for more information.
4
Configures mount points; must be a list containing six values. Refer to Mounts for more information.
5
Specifies whether to remove default host SSH keys. Refer to Host Keys for more information.
6
Specifies key types to generate. Refer to Host Keys for more information.
7
cloud-init runs at multiple stages of boot. Set this option so that cloud-init can log all stages to its log file. Find more information on this option in the cloud-config.txt file in the usr/share/doc/cloud-init/examples directory.
8
Enables or disables VMware vSphere customization
9
The modules in this section are services that run when the cloud-init service starts, early in the boot process.
10
These modules run during cloud-init configuration, after initial boot.
11
These modules run in the final phase of cloud-init, after the configuration finishes.
12
Specifies details about the default user. Refer to Users and Groups for more information.
13
Specifies the distribution
14
Specifies the main directory that contains cloud-init-specific subdirectories. Refer to Directory layout for more information.
15
Specifies where templates reside
16
The name of the SSH service

2.5. The cloud.cfg.d directory

cloud-init acts upon directives that you provide and configure. Typically, those directives are included in the cloud.cfg.d directory.

Note

While you can configure modules by adding user data directives within the cloud.cfg file, as a best practice consider leaving cloud.cfg unmodified. Add your directives to the /etc/cloud/cloud.cfg.d directory. Adding directives to this directory can make future modifications and upgrades easier.

There are multiple ways to add directives. You can include directives in a file named *.cfg, which includes the heading #cloud-config. Typically, the directory would contain multiple *cfg files. There are other options for adding directives, for example, you can add a user data script. Refer to User-Data Formats for more information.

2.6. The default 05_logging.cfg file

The 05_logging.cfg file sets logging information for cloud-init. The /etc/cloud/cloud.cfg.d directory includes this file, along with other cloud-init directives that you add.

cloud-init uses the logging configuration in 05_logging.cfg by default. What follows are the default contents of the file for Red Hat Enterprise Linux (RHEL).

## This yaml formatted config file handles setting
## logger information.  The values that are necessary to be set
## are seen at the bottom.  The top '_log' are only used to remove
## redundancy in a syslog and fallback-to-file case.
##
## The 'log_cfgs' entry defines a list of logger configs
## Each entry in the list is tried, and the first one that
## works is used.  If a log_cfg list entry is an array, it will
## be joined with '\n'.
_log:
 - &log_base |
   [loggers]
   keys=root,cloudinit

   [handlers]
   keys=consoleHandler,cloudLogHandler

   [formatters]
   keys=simpleFormatter,arg0Formatter

   [logger_root]
   level=DEBUG
   handlers=consoleHandler,cloudLogHandler

   [logger_cloudinit]
   level=DEBUG
   qualname=cloudinit
   handlers=
   propagate=1

   [handler_consoleHandler]
   class=StreamHandler
   level=WARNING
   formatter=arg0Formatter
   args=(sys.stderr,)

   [formatter_arg0Formatter]
   format=%(asctime)s - %(filename)s[%(levelname)s]: %(message)s

   [formatter_simpleFormatter]
   format=[CLOUDINIT] %(filename)s[%(levelname)s]: %(message)s
 - &log_file |
   [handler_cloudLogHandler]
   class=FileHandler
   level=DEBUG
   formatter=arg0Formatter
   args=('/var/log/cloud-init.log',)
 - &log_syslog |
   [handler_cloudLogHandler]
   class=handlers.SysLogHandler
   level=DEBUG
   formatter=simpleFormatter
   args=("/dev/log", handlers.SysLogHandler.LOG_USER)

log_cfgs:
# Array entries in this list will be joined into a string
# that defines the configuration.
#
# If you want logs to go to syslog, uncomment the following line.
# - [ *log_base, *log_syslog ]
#
# The default behavior is to just log to a file.
# This mechanism that does not depend on a system service to operate.
 - [ *log_base, *log_file ]
# A file path can also be used.
# - /etc/log.conf

# This tells cloud-init to redirect its stdout and stderr to
# 'tee -a /var/log/cloud-init-output.log' so the user can see output
# there without needing to look on the console.
output: {all: '| tee -a /var/log/cloud-init-output.log'}

Additional resources

2.7. The cloud-init /var/lib/cloud directory layout

When cloud-init first runs, it creates a directory layout that includes information about your instance and cloud-init configuration.

What follows is the sample directory layout for cloud-init.

The directory can include optional directories, such as /scripts/vendor.

/var/lib/cloud/
    - data/
       - instance-id
       - previous-instance-id
       - previous-datasource
       - previous-hostname
       - result.json
       - set-hostname
       - status.json
    - handlers/
    - instance
       - boot-finished
       - cloud-config.txt
       - datasource
       - handlers/
       - obj.pkl
       - scripts/
       - sem/
       - user-data.txt
       - user-data.txt.i
       - vendor-data.txt
       - vendor-data.txt.i
    - instances/
        f111ee00-0a4a-4eea-9c17-3fa164739c55/
          - boot-finished
          - cloud-config.txt
          - datasource
          - handlers/
          - obj.pkl
          - scripts/
          - sem/
          - user-data.txt
          - user-data.txt.i
          - vendor-data.txt
          - vendor-data.txt.i
    - scripts/
       - per-boot/
       - per-instance/
       - per-once/
       - vendor/
    - seed/
    - sem/
       - config_scripts_per_once.once

Additional resources

Chapter 3. Configuring cloud-init

This chapter includes examples of the most common configuration tasks for cloud-init.

Your cloud-init configuration can require that you add directives to the cloud.cfg file and the cloud.cfg.d directory. Alternatively, your specific data source might require that you add directives to files, such as a user data file and a metadata file. A data source might require that you upload your directives to an HTTP server. Check the requirements of your data source and add directives accordingly.

3.1. Creating a virtual machine that includes cloud-init for a NoCloud datasource

What follows is a sample procedure for creating a new VM that includes cloud-init. In this procedure, you create a meta-data and user-data file. Your meta-data file includes instance details. Your user-data file includes information to create a user and grant access. You then include those files in a new ISO image, and you attach the ISO file to a new VM you create from a KVM Guest Image. In this scenario, the datasource is NoCloud.

Procedure

  1. Create a directory named cloudinitiso and move into it.

    $ mkdir cloudinitiso
    $ cd cloudinitiso
  2. Create a file named meta-data. Add the following information to the file.

    instance-id: citest
    local-hostname: citest-1
  3. Create a file named user-data. Include the following information in the file.

    #cloud-config
    password: cilogon
    chpasswd: {expire: False}
    ssh_pwauth: True
    ssh_authorized_keys:
      - ssh-rsa AAA...fhHQ== sample@redhat.com
    Note

    The final line of the user-data file references an SSH public key. Find your SSH public keys in ~/.ssh/id_rsa.pub. When trying this sample procedure, modify the line to include one of your public keys.

  4. Use the genisoimage command to create an ISO image that includes user-data and meta-data.

    # genisoimage -output ciiso.iso -volid cidata -joliet -rock user-data meta-data
    
    I: -input-charset not specified, using utf-8 (detected in locale settings)
    Total translation table size: 0
    Total rockridge attributes bytes: 331
    Total directory bytes: 0
    Path table size(bytes): 10
    Max brk space used 0
    183 extents written (0 MB)
  5. Download a KVM Guest Image from the Red Hat Customer Portal to the /var/lib/libvirt/images directory.
  6. Create a new VM from the KVM Guest Image using the virt-install command. Include the ISO image you created as an attachment to the image.

    virt-install \
        --memory 4096 \
        --vcpus 4 \
        --name mytestcivm \
        --disk /var/lib/libvirt/images/rhel-8.1-x86_64-kvm.qcow2,device=disk,bus=virtio,format=qcow2 \
        --disk /home/sample/cloudinitiso/ciiso.iso,device=cdrom \
        --os-type Linux \
        --os-variant rhel8.0 \
        --virt-type kvm \
        --graphics none \
        --import
  7. Log on to your image as cloud-user. Your password is cilogon.

    citest-1 login: cloud-user
    Password:
    [cloud-user@citest-1 ~]$

Verification Steps

  • Check the cloud-init status to see that it has completed its tasks.

    [cloud-user@citest-1 instance]$ cloud-init status
    status: done
  • cloud-init creates the cloud-init directory layout under /var/lib/cloud when it runs, and it updates or changes certain directory contents based upon the directives you have specified.

    For example, you can confirm that the datasource is NoCloud by checking the datasource file.

    $ cd /var/lib/cloud/instance
    $ cat datasource
    DataSourceNoCloud: DataSourceNoCloud [seed=/dev/sr0][dsmode=net]

    cloud-init copies user-data into /var/lib/cloud/instance/user-data.txt.

    $cat user-data.txt
    #cloud-config
    password: cilogon
    chpasswd: {expire: False}
    ssh_pwauth: True
    ssh_authorized_keys:
      - ssh-rsa AAA...fhHQ== sample@redhat.com

    These are samples. The cloud-init directory layout includes much more information.

Note

For OpenStack, the Instances and Images Guide includes information for configuring an instance using cloud-init. See Creating a customized instance for specific procedures.

Additional resources

3.2. Expiring a cloud user password with cloud-init

You can force cloud-user to change the cloud-user password at the first login. Perform the following procedure to expire a password.

Procedure

  1. Depending upon the requirements of your datasource, open your user-data file for editing, or otherwise add the following directive to the cloud.cfg.d directory.

    Note

    All user directives include #cloud-config at the top of the file so that cloud-init recognizes the file as containing user directives. When you include directives in the cloud.cfg.d directory, name the file *.cfg, and always include #cloud-config at the top of the file.

  2. Change the line chpasswd: {expire: False} to chpasswd: {expire: True}.

    #cloud-config
    password: mypassword
    chpasswd: {expire: True}
    ssh_pwauth: True
    ssh_authorized_keys:
      - ssh-rsa AAA...SDvz user1@yourdomain.com
      - ssh-rsa AAB...QTuo user2@yourdomain.com

    This works to expire the password because password and chpasswd operate on the default user unless you indicate otherwise.

    Note

    This is a global setting. When you set chpasswd to True, all users you create need to change their passwords when they log in.

3.3. Changing a default user name with cloud-init

You can change the default user name to something other than cloud-user.

Procedure

  1. Depending upon the requirements of your datasource, open your user-data file for editing, or otherwise add the following directive to the cloud.cfg.d directory.

    Note

    All user directives include #cloud-config at the top of the file so that cloud-init recognizes the file as containing user directives. When you include directives in the cloud.cfg.d directory, name the file *.cfg, and always include #cloud-config at the top of the file.

  2. Add the line user: <username>, replacing <username> with the new default user name.

    #cloud-config
    user: username
    password: mypassword
    chpasswd: {expire: False}
    ssh_pwauth: True
    ssh_authorized_keys:
      - ssh-rsa AAA...SDvz user1@yourdomain.com
      - ssh-rsa AAB...QTuo user2@yourdomain.com

3.4. Setting a root password with cloud-init

To set the root password, create a user list.

Procedure

  1. Depending upon the requirements of your datasource, open your user-data file for editing, or otherwise add the following directive to the cloud.cfg.d directory.

    Note

    All user directives include #cloud-config at the top of the file so that cloud-init recognizes the file as containing user directives. When you include directives in the cloud.cfg.d directory, name the file *.cfg, and always include #cloud-config at the top of the file.

  2. Create a user list in the chpasswd section of the file. The format is shown in the following sample.

    Note

    White space is significant. Do not include white space before or after the colon in your user list. If you include white space, the password is set with a space in it.

    #cloud-config
    ssh_pwauth: True
    ssh_authorized_keys:
      - ssh-rsa AAA...SDvz user1@yourdomain.com
      - ssh-rsa AAB...QTuo user2@yourdomain.com
    chpasswd:
      list: |
         root:myrootpassword
         cloud-user:mypassword
      expire: False
    Note

    If you use this method to set the user password, you must set all passwords in this section.

3.5. Managing Red Hat subscriptions with cloud-init

You can use the rh_subscription directive to register your system. Samples follow. For each subscription, you would edit your user data.

Procedure

The following example uses the auto-attach and service-level options.

  • Under rh_subscription, add your username and password, set auto-attach to True, and set service-level to self-support.

    rh_subscription:
      username: sample@redhat.com
      password: 'mypassword'
      auto-attach: True
      service-level: self-support
    Note

    The service-level option requires that you use the auto-attach option.

The following example uses the activation-key and org options.

  • Under rh_subscription, add your activation key and org number and set auto-attach to True.

    rh_subscription:
      activation-key: example_key
      org: 12345
      auto-attach: True

The following example adds a subscription pool.

  • Under rh_subscription, add your username, password, and pool number.

    rh_subscription:
      username: sample@redhat.com
      password: 'password'
      add-pool: XYZ01234567
    Note

    This sample is the equivalent of the subscription-manager attach --pool=XYZ01234567 command.

The following example sets a server host name in the /etc/rhsm/rhsm.conf file.

  • Under rh_subscription, add your username, password, server-hostname, and set auto-attach to True.

    rh_subscription:
      username: sample@redhat.com
      password: 'password'
      server-hostname: test.example.com
      auto-attach: True

3.6. Adding users and user options with cloud-init

You create and describe users in a users section. You can modify the section to add more users to your initial system configuration, and you can set additional user options.

If you add the users section, you must also set the default user options in this section.

Procedure

  1. Depending upon the requirements of your datasource, open your user-data file for editing, or otherwise add the following directive to the cloud.cfg.d directory.

    Note

    All user directives include #cloud-config at the top of the file so that cloud-init recognizes the file as containing user directives. When you include directives in the cloud.cfg.d directory, name the file *.cfg, and always include #cloud-config at the top of the file.

  2. Add or modify the users section to add users.

    • If you want cloud-user to be the default user created along with the other users you specify, ensure that you add default as the first entry in the section. If it is not the first entry, cloud-user is not created.
    • By default, users are labeled as unconfined_u if there is not an selinux-user value.

      #cloud-config
      users:
        - default
        - name: user2
          gecos: User N. Ame
          selinux-user: staff_u
          groups: users,wheel
          ssh_pwauth: True
          ssh_authorized_keys:
            - ssh-rsa AA..vz user@domain.com
      chpasswd:
        list: |
          root:password
          cloud-user:mypassword
          user2:mypassword2
        expire: False
      Note
      • The example places the user user2 into two groups, users and wheel.
      • As of cloud-init 0.7.5, the group list does not support white space. Refer to BZ 1126365 for more information.

3.7. Running first boot commands with cloud-init

You can use the runcmd and bootcmd sections to execute commands during startup and initialization.

The bootcmd section executes early in the initialization process and by default runs on every boot. The runcmd section executes near the end of the process and is only executed during the first boot and initialization.

Procedure

  1. Depending upon the requirements of your datasource, open your user-data file for editing, or otherwise add the following directive to the cloud.cfg.d directory.

    Note

    All user directives include #cloud-config at the top of the file so that cloud-init recognizes the file as containing user directives. When you include directives in the cloud.cfg.d directory, name the file *.cfg, and always include #cloud-config at the top of the file.

  2. Add the sections for bootcmd and runcmd; include commands you want cloud-init to execute.

    #cloud-config
    users:
      - default
      - name: user2
        gecos: User N. Ame
        groups: users
    chpasswd:
      list: |
        root:password
        fedora:myfedpassword
        user2:mypassword2
      expire: False
    bootcmd:
     - echo New MOTD >> /etc/motd
    runcmd:
     - echo New MOTD2 >> /etc/motd

3.8. Adding additional sudoers with cloud-init

You can configure a user as a sudoer by adding a sudo and groups entry to the users section.

Procedure

  1. Depending upon the requirements of your datasource, open your user-data file for editing, or otherwise add the following directive to the cloud.cfg.d directory.

    Note

    All user directives include #cloud-config at the top of the file so that cloud-init recognizes the file as containing user directives. When you include directives in the cloud.cfg.d directory, name the file *.cfg, and always include #cloud-config at the top of the file.

  2. Add a sudo entry and specify the user access. For example, sudo: ALL=(ALL) NOPASSWD:ALL allows a user unrestricted user access.
  3. Add a groups entry and specify the groups that include the user.

    #cloud-config
    users:
      - default
      - name: user2
        gecos: User D. Two
        sudo: ["ALL=(ALL) NOPASSWD:ALL"]
        groups: wheel,adm,systemd-journal
        ssh_pwauth: True
        ssh_authorized_keys:
          - ssh-rsa AA...vz user@domain.com
    chpasswd:
      list: |
        root:password
        cloud-user:mypassword
        user2:mypassword2
      expire: False

3.9. Setting up a static networking configuration with cloud-init

You can set up your network configuration with cloud-init by adding a network-interfaces section to your metadata.

Red Hat Enterprise Linux provides its default networking service through NetworkManager, which is a dynamic network control and configuration daemon that keeps network devices and connections up and active when they are available. Refer to Getting Started with NetworkManager for more information on NetworkManager.

Your datasource might provide a network configuration. Refer to the cloud-init documentation section Network Configuration Sources for more information.

If you specify no network configuration for cloud-init and have not disabled network configuration, cloud-init tries to determine if any attached devices have a connection. If it finds a connected device, it generates a network configuration that issues a DHCP request on the interface. Refer to the cloud-init documentation section Fallback Network Configuration for more information.

Procedure

The following example adds a static networking configuration.

  1. Depending upon the requirements of your datasource, open your meta-data file for editing, or otherwise add the following directive to the cloud.cfg file or the cloud.cfg.d directory.
  2. Add a network-interfaces section.

    network-interfaces: |
      iface eth0 inet static
      address 192.168.1.10
      network 192.168.1.0
      netmask 255.255.255.0
      broadcast 192.168.1.255
      gateway 192.168.1.254
    bootcmd:
      - ifdown eth0
      - ifup eth0
Note

You can disable a network configuration by adding the following information to your metadata.

network
  config: disabled

Additional resources

3.10. Configuring only a root user with cloud-init

You can configure your user data so that you have a root user and no other users.

Procedure

  1. Depending upon the requirements of your datasource, open your user-data file for editing, or otherwise add the following directive to the cloud.cfg.d directory.

    Note

    All user directives include #cloud-config at the top of the file so that cloud-init recognizes the file as containing user directives. When you include directives in the cloud.cfg.d directory, name the file *.cfg, and always include #cloud-config at the top of the file.

  2. Create an entry for the user root in the users section.

    The simple example that follows includes a users section with only the name option.

    users:
      - name: root
    chpasswd:
      list: |
        root:password
      expire: False
  3. Optionally, set up SSH keys for the root user.

    users:
      - name: root
        ssh_pwauth: True
        ssh_authorized_keys:
          - ssh-rsa AA..vz user@domain.com

3.11. Setting up storage with container-storage-setup in cloud-init

You can set up storage by referencing the container-storage-setup utility within the write_files module.

Procedure

  1. Depending upon the requirements of your datasource, open your user-data file for editing, or otherwise add the following directive to the cloud.cfg.d directory.

    Note

    All user directives include #cloud-config at the top of the file so that cloud-init recognizes the file as containing user directives. When you include directives in the cloud.cfg.d directory, name the file *.cfg, and always include #cloud-config at the top of the file.

  2. Add or modify the write_files module to include the path to the container-storage-setup utility.

    The following example sets the size of the root logical volume to 6GB rather than the default 3GB.

    write_files:
      - path: /etc/sysconfig/docker-storage-setup
        permissions: 0644
        owner: root
        content: |
        ROOT_SIZE=6G
    Note

    Prior to RHEL 7.4, container-storage-setup was called docker-storage-setup. If you are using OverlayFS for storage, as of RHEL 7.4 you can now use that type of file system with SELinux in enforcing mode.

3.12. Changing the system locale with cloud-init

You can configure the system location with the locale module.

Procedure

  1. Depending upon the requirements of your datasource, open your meta-data file for editing, or otherwise add the following directive to the cloud.cfg file or the cloud.cfg.d directory.
  2. Add the locale directive, specifying the location. The following sample sets the locale to ja_JP (Japan) with UTF-8 encoding.
#cloud-config
locale: ja_JP.UTF-8

Additional resources

3.13. cloud-init and shell scripts

You can add list values or string values to bootcmd or runcmd. You can also provide a shell script within your userdata.

  • If you use a list value for bootcmd or runcmd, each list item is run in turn using execve.
  • If you use a string value, then the entire string is run as a shell script.
  • If you want to use cloud-init to run a shell script, you can provide a shell script (complete with shebang (#!) ) instead of providing cloud-init with a .yaml file.

Refer to Run commands on first boot for examples of how to put shell scripts in bootcmd and runcmd.

3.14. Preventing cloud-init from updating config files

When you create or restore an instance from a backup image, the instance ID changes. The change in instance ID can cause cloud-init to update configuration files.

Perform the following procedure to ensure that cloud-init does not update certain configuration files when you create or restore from backup.

Procedure

  1. Open the /etc/cloud/cloud.cfg file for editing.
  2. Comment out or remove the configuration that you do not want cloud-init to update when you restore your instance.

    For example, to avoid updating the SSH key file, remove -ssh from the cloud_init_modules section.

    cloud_init_modules:
     - disk_setup
     - migrator
     - bootcmd
     - write-files
     - growpart
     - resizefs
     - set_hostname
     - update_hostname
     - update_etc_hosts
     - rsyslog
     - users-groups
     # - ssh

Verification steps

You can check to see which configuration files cloud-init has updated. To do so, examine the /var/log/cloud/cloud-init.log file. Updated files are logged during instance startup with messages beginning with Writing to. An example follows.

2019-09-03 00:16:07,XXX - util.py[DEBUG]: Writing to /root/.ssh/authorized_keys - wb: [XXX] 554 bytes
2019-09-03 00:16:08,XXX - util.py[DEBUG]: Writing to /etc/ssh/sshd_config - wb: [XXX] 3905 bytes

3.15. Modifying a VM created from a KVM Guest Image after cloud-init has run

This section provides a sample procedure for when you want to modify your cloud-init configuration before rerunning cloud-init. When you launch a VM that includes the cloud-init package installed and enabled, cloud-init runs in its default state on that initial boot of your VM.

Procedure

  1. Log in to your VM.
  2. Add or change directives, for example, modify the cloud.cfg file in the /etc/cloud directory or add directives to the /etc/cloud/cloud.cfg.d directory.
  3. Run the cloud-init clean command to clean directories so that cloud-init can rerun. You can also run the following commands as root to clean the VM.

    `rm -Rf /var/lib/cloud/instances/*`
    `rm -Rf /var/lib/cloud/instance`
    `rm -Rf /var/lib/cloud/data/*`
    Note

    You can save the cleaned image as a new image and use that image for multiple VMs. The new VMs run cloud-init using your updated cloud-init configuration.

  4. Rerun cloud-init or reboot the VM.

    cloud-init reruns, implementing the configuration changes you made.

3.16. Modifying a VM for a specific datasource after cloud-init has run

This section provides a sample procedure for when you want to modify your cloud-init configuration before rerunning cloud-init. The following procedure uses OpenStack as an example. Note that the procedure varies based upon your datasource.

Procedure

  1. Create and launch an instance for the OpenStack Platform. Refer to Virtual Machine Instances for information on creating instances for OpenStack. In this example, our virtual machine includes cloud-init, which runs upon boot of the virtual machine.
  2. Add or change directives. For example, modify the user-data.file file that is stored on the OpenStack HTTP server.
  3. Clean the virtual machine. Run the following commands as root.

    `rm -rf /etc/resolv.conf /run/cloud-init`
    `userdel -rf cloud-user`
    `hostnamectl set-hostname localhost.localdomain`
    `rm /etc/NetworkManager/conf.d/99-cloud-init.conf`
    Note

    You can save the cleaned image as a new image and use that image for multiple virtual machines. The new virtual machines run cloud-init using your updated cloud-init configuration.

  4. Rerun cloud-init or reboot the virtual machine.

    Cloud-init reruns, implementing the configuration changes you made.

3.17. Troubleshooting cloud-init

You can troubleshoot your instance after cloud-init has run by examining your configuration and log files. Once you have identified the issue, you can rerun cloud-init on your instance.

You can run cloud-init from the command line using the cloud-init command. To view the command syntax, along with a description of the optional arguments and subcommands, run the cloud-init --help command. The basic syntax follows.

cloud-init [-h] [--version] [--file FILES] [--debug] [--force]
{init,modules,single,query,dhclient-hook,features,analyze,devel,collect-logs,clean,status}

The procedure that follows offers ideas for identifying issues with cloud-init and samples for rerunning the program.

Procedure

  1. Review the cloud-init configuration files.

    1. Examine the /etc/cloud/cloud.cfg configuration file. Check which modules are included under cloud_init_modules, cloud_config_modules, and cloud_final_modules.
    2. Check directives (*.cfg files) in the /etc/cloud/cloud.cfg.d directory.
  2. Review the /var/log/cloud-init.log and /var/log/cloud-init-output.log files for details on a specific issue. For example, if the issue was that the root partition was not automatically extended, check log messages for growpart. If the file system was not extended, check log messages for resizefs. A sample grep command for resizefs follows.

    # grep resizefs /var/log/cloud-init.log
    Note

    growpart does not support LVM. If your root partition is based in LVM, the root partition is not automatically extended upon first boot.

  3. Rerun cloud-init. Sample scenarios follow. Run commands as root.

    • Rerun cloud-init with only the init modules.

      /usr/bin/cloud-init -d init
    • Rerun cloud-init with all modules in your configuration.

      /usr/bin/cloud-init -d modules
    • Delete the cloud-init cache and force cloud-init to run after boot.

      rm -rf /var/lib/cloud/* && /usr/bin/cloud-init -d init
    • Run the following commands to clean directories and simulate a clean instance.

      rm -Rf /var/lib/cloud/instances/*
      rm -Rf /var/lib/cloud/instance
      rm -Rf /var/lib/cloud/data/*
      reboot
    • Run the following commands to rerun cloud-init.

      cloud-init init --local
      cloud-init init

Additional resources

Legal Notice

Copyright © 2020 Red Hat, Inc.
The text of and illustrations in this document are licensed by Red Hat under a Creative Commons Attribution–Share Alike 3.0 Unported license ("CC-BY-SA"). An explanation of CC-BY-SA is available at http://creativecommons.org/licenses/by-sa/3.0/. In accordance with CC-BY-SA, if you distribute this document or an adaptation of it, you must provide the URL for the original version.
Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law.
Red Hat, Red Hat Enterprise Linux, the Shadowman logo, the Red Hat logo, JBoss, OpenShift, Fedora, the Infinity logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries.
Linux® is the registered trademark of Linus Torvalds in the United States and other countries.
Java® is a registered trademark of Oracle and/or its affiliates.
XFS® is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/or other countries.
MySQL® is a registered trademark of MySQL AB in the United States, the European Union and other countries.
Node.js® is an official trademark of Joyent. Red Hat is not formally related to or endorsed by the official Joyent Node.js open source or commercial project.
The OpenStack® Word Mark and OpenStack logo are either registered trademarks/service marks or trademarks/service marks of the OpenStack Foundation, in the United States and other countries and are used with the OpenStack Foundation's permission. We are not affiliated with, endorsed or sponsored by the OpenStack Foundation, or the OpenStack community.
All other trademarks are the property of their respective owners.