Step 3: Modifying cloud-init configuration files

After installing cloud-init, you need to update the configuration files as follows:

Procedure

1. Open the cloud-init configuration file /etc/cloud/cloud.cfg and update the following configuration items:

   • Enable the root account and set it as the default user for cloud-init:

     default_user:
       name: root
       lock_passwd: false

     disable_root: false
     ssh_pwauth:  true
     chpasswd:
       expire: false

   • Set the cloud-init data source to config drive:

     datasource_list: [ConfigDrive, None]
     datasource:
       ConfigDrive:
         dsmode: local

   • Comment out growpart and resizefs to disable the cloud-init auto extension partition modules:

     # - growpart
     # - resizefs

   Below is the example of the configuration of cloud-init-18.5-3.el7.centos.x86_64 on CentOS 7.4:

   users:
     - default
   
   #Modify disable_root, ssh_pwauth, chpasswd, datasource_list, datasource ==>
   disable_root: false
   ssh_pwauth:  true
   chpasswd:
     expire: false
   
   datasource_list: [ConfigDrive, None]
   datasource:
     ConfigDrive:
       dsmode: local
   #<==The modification ends here
   
   mount_default_fields: [~, ~, 'auto', 'defaults,nofail,x-systemd.requires=Cloud-init.service', '0', '2']
   resize_rootfs_tmp: /dev
   ssh_deletekeys:   0
   ssh_genkeytypes:  ~
   syslog_fix_perms: ~
   disable_vmware_customization: false
   
   cloud_init_modules:
     - disk_setup
     - migrator
     - bootcmd
     - write-files
   #Comment out the following two items
   # - growpart
   # - resizefs
     - set_hostname
     - update_hostname
     - update_etc_hosts
     - rsyslog
     - users-groups
     - ssh
   
   cloud_config_modules:
     - 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:
     - 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:
     #Modify default_user ==>
     default_user:
       name: root
       lock_passwd: false
     #<==The modification ends here
     distro: rhel
     paths:
       cloud_dir: /var/lib/cloud
       templates_dir: /etc/cloud/templates
     ssh_svcname: sshd
   
   # vim:syntax=yaml

2. When a virtual machine boots too fast, especially when the cluster where it resides has Boost mode enabled, cloud-init might be unexpectedly booted before the config drive is mounted, which makes DataSource undetectable. To prevent this issue, you will need to open the configuration file at /usr/lib/systemd/system/cloud-init-local.service and add ExecStartPre=/bin/sleep 2 to its content.