Customize VM Instance with Cloud-init

This Platform9 OpenStack tutorial describes tips on using various options to customize a virtual machine using cloud-init.

Customize Virtual Machine Hostname

Virtual machines deployed using cloud-init enabled images will by default be configured with hostname created using the name given to the virtual machine, and a randomization suffix.

Set Default Password and Inject Custom Script Using User Data

Create a text file with following information.

Paste the configuration above to the cloud-init config text area:

where:

The first line is NOT a comment and should not be skipped or modified. It is a directive indicating that the content that follows should be merged with cloud.cfg that the virtual machine instance already has.

This is a YAML file. Be careful with the YAML syntax around spacing. Failing to include appropriate spacing where required will result in silent failures (For example, inability to logon to the instance).

Verify the YAML syntax by writing small sample python code such as this:

Python
    
 
import yamlfile = open("/tmp/pf9-user-data.txt")obj = yaml.load(file)print obj
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The output should be a Python dict string representation of the above YAML file.

Output
    
{'password': 'winterwonderland', 'chpasswd': {'expire': False}, 'ssh_pwauth': True, 'runcmd': [['sh', '-c', 'echo "Hello World from PF9" > /tmp/pf9.txt']]}
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'winterwonderland' is the desired default password you wish to set for this virtual machine
'runcmd' is a list of commands you would like to inject into this virtual machine. Each element can be a string or another list (like execev). Following article offers comprehensive details: Cloud-Init: Run commands on first boot.

Finally, invoke Nova command via CLI or REST API to create a new instance, passing the extra parameters for customization.

CLI
    
# format# nova boot --config-drive=true --image <name of the image> --flavor <flavor-id> --nic net-id=<network id to connect> --user-data<path to user-data file> <name of the instance># examplenova boot --config-drive=true --image ubuntu-16.04-cloudimg.img --flavor 2 --nic net-id=c3454717-f813-4419-9203-ceb78b0aa3f9 --user-data /tmp/pf9-user-data.txt pf9-ubuntu-test-1
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Inject SSH Key-Pair into Virtual Machine

First, generate a new ssh key pair to be used for the new virtual machine:

Bash
    
 
ssh-keygen -t rsa -C <your email address>
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Now add the key pair to Nova:

Nova
    
 
# format# nova keypair-add -p<path to the public key> <name of the key># examplenova keypair-add -p ~/.ssh/id_rsa.pub rparikh-ssh
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List key pairs registered with Nova:

Nova
    
 
nova keypair-list
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Now with nova boot command you can optionally pass the key-name as the argument:

Nova
    
nova boot --config-drive=true --image ubuntu-16.04-server-cloudimg-amd64-disk1.img --flavor 2 --nic net-id=c3454717-f813-4419-9203-ceb78b0aa3f9 --key-name pf9-ssh --user-data /tmp/pf9-user-data.txt pf9-ubuntu-test-2
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That's it. Once the virtual machine instance is active, you can ssh into the instance using the private key.

Example cloud-config File with Comments

Some features only work with cloudinit >= v0.7.5 (Ubuntu 14 or newer, and CentOS 7.x)

YAML
    
#cloud-config# 1. Create a new groupgroups:  - pf9testgroup# 2. Change default user add to new group and add sudo accesssystem_info:  default_user:    name: default-user    lock_passwd: true    groups: pf9testgroup    sudo: ["ALL=(ALL) NOPASSWD:ALL"]# 3. Change password of default userpassword: groovychpasswd: { expire: False }ssh_pwauth: True# 4. Create new user and also create the default user# 5. Add ssh-key# 6. Add password ("groovy")# 7. Add to group# 8. Add sudo accessusers:  - default  - name: new-user    ssh-authorized-keys:      - ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAGEArdM+gvsEq8BBvtTRHPa23mRsGSWDlWi9gvRSjhvcgYhsnssEy/QvSokqQgfJ7O8uEf3JEvDhGbX/G65YzLeyO4hS+R86vGAyyJuLXPuAyrWwccWdeOJeno26P5CutRVp test_key@platform9    lock_passwd: false    groups: pf9testgroup    passwd: $6$whatwhat1$mkCxCGXIEgF.6CjvGsdcoseQNFy/IvKS3dxz64uHxH7Y75KvJVMc96oEjhgd2ixrMpTwNjiWVG967009HqAyT1    sudo: ["ALL=(ALL) NOPASSWD:ALL"]# 9. File creationwrite_files:  - content: |      # This will go inside the file      OK Platform9, this is working.    path: /tmp/pf9_write_file.txt    permissions: '0777'# 10. Run arbitrary commandsruncmd:  - [ 'sh', '-c', 'echo "Hello World from PF9" > /tmp/pf9_hello.txt']  - [ 'sh', '-c', 'date > /tmp/pf9_date.txt']# 11. Set hostnamehostname: pf9-hostname# 12. Set timezonetimezone: US/Eastern# 13. Install packagespackages:  - git  - gdb# 14. Restart network service for Redhat guests (this will fail gracefully on Debian guests)bootcmd:  - [ 'sh', '-c', 'service network restart' ]
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