Creating a template for a kickstart file
by Uday R. Sawant, William Leemans, Jonathan Hobson, Oliver Pelz
Linux: Powerful Server Administration
- Linux: Powerful Server Administration
- Table of Contents
- Linux: Powerful Server Administration
- Linux: Powerful Server Administration
- Credits
- Preface
- 1. Module 1
- 1. Managing Users and Groups
- 2. Networking
- Introduction
- Connecting to a network with a static IP
- Installing the DHCP server
- Installing the DNS server
- Hiding behind the proxy with squid
- Being on time with NTP
- Discussing load balancing with HAProxy
- Tuning the TCP stack
- Troubleshooting network connectivity
- Securing remote access with OpenVPN
- Securing a network with uncomplicated firewall
- Securing against brute force attacks
- Discussing Ubuntu security best practices
- 3. Working with Web Servers
- Introduction
- Installing and configuring the Apache web server
- Serving dynamic contents with PHP
- Hosting multiple websites with a virtual domain
- Securing web traffic with HTTPS
- Installing Nginx with PHP_FPM
- Setting Nginx as a reverse proxy
- Load balancing with Nginx
- Setting HTTPs on Nginx
- Benchmarking and performance tuning of Apache
- Securing the web server
- Troubleshooting the web server
- 4. Working with Mail Servers
- 5. Handling Databases
- Introduction
- Installing relational databases with MySQL
- Storing and retrieving data with MySQL
- Importing and exporting bulk data
- Adding users and assigning access rights
- Installing web access for MySQL
- Setting backups
- Optimizing MySQL performance – queries
- Optimizing MySQL performance – configuration
- Creating MySQL replicas for scaling and high availability
- Troubleshooting MySQL
- Installing MongoDB
- Storing and retrieving data with MongoDB
- 6. Network Storage
- 7. Cloud Computing
- 8. Working with Containers
- Introduction
- Installing LXD, the Linux container daemon
- Deploying your first container with LXD
- Managing LXD containers
- Managing LXD containers – advanced options
- Setting resource limits on LXD containers
- Networking with LXD
- Installing Docker
- Starting and managing Docker containers
- Creating images with a Dockerfile
- Understanding Docker volumes
- Deploying WordPress using a Docker network
- Monitoring Docker containers
- Securing Docker containers
- 9. Streaming with Ampache
- 10. Communication Server with XMPP
- 11. Git Hosting
- Introduction
- Installing Git
- Creating a local repository with Git CLI
- Storing file revisions with Git commit
- Synchronizing the repository with a remote server
- Receiving updates with Git pull
- Creating repository clones
- Installing GitLab, your own Git hosting
- Adding users to the GitLab server
- Creating a repository with GitLab
- Automating common tasks with Git hooks
- 12. Collaboration Tools
- 13. Performance Monitoring
- 14. Centralized Authentication Service
- 2. Module 2
- 1. Installing CentOS
- Introduction
- Downloading CentOS and confirming the checksum on Windows or OS X
- Creating USB installation media on Windows or OS X
- Performing an installation of CentOS using the graphical installer
- Running a netinstall over HTTP
- Installing CentOS 7 using a kickstart file
- Getting started and customising the boot loader
- Troubleshooting the system in rescue mode
- Updating the installation and enhancing the minimal install with additional administration and development tools
- 2. Configuring the System
- Introduction
- Navigating text files with less
- Introduction to Vim
- Speaking the right language
- Synchronizing the system clock with NTP and the chrony suite
- Setting your hostname and resolving the network
- Building a static network connection
- Becoming a superuser
- Customizing your system banners and messages
- Priming the kernel
- 3. Managing the System
- Introduction
- Knowing and managing your background services
- Troubleshooting background services
- Tracking system resources with journald
- Configuring journald to make it persistent
- Managing users and their groups
- Scheduling tasks with cron
- Synchronizing files and doing more with rsync
- Maintaining backups and taking snapshots
- Monitoring important server infrastructure
- Taking control with GIT and Subversion
- 4. Managing Packages with YUM
- 5. Administering the Filesystem
- 6. Providing Security
- 7. Building a Network
- 8. Working with FTP
- 9. Working with Domains
- 10. Working with Databases
- 11. Providing Mail Services
- 12. Providing Web Services
- 13. Operating System-Level Virtualization
- 14. Working with SELinux
- 15. Monitoring IT Infrastructure
- 1. Installing CentOS
- 3. Module 3
- 1. Working with KVM Guests
- 2. Deploying RHEL "En Masse"
- 3. Configuring Your Network
- 4. Configuring Your New System
- 5. Using SELinux
- 6. Orchestrating with Ansible
- 7. Puppet Configuration Management
- 8. Yum and Repositories
- 9. Securing RHEL 7
- 10. Monitoring and Performance Tuning
- Bibliography
- Index
A template is one of the core modules of Ansible. It is used to easily generate files (for example, configuration files) based on a common set of facts. It uses the Jinja2 template engine to interpret template files.
For this recipe, we'll use a simple kickstart script that is generic enough to deploy any host. Refer to Chapter 2, Deploying RHEL "En Masse", to find out about kickstart files.
The facts that we need for this host are repo_url, root_password_hash, ntp_servers, timezone, ipv4_address, ipv4_netmask, ipv4_gateway, and dns_servers.
Create the kickstart file in your playbook's template folder (~/playbooks/templates/kickstart/rhel7.ks) with the following content:
install
url --url={{ repo_url }}
skipx
text
reboot
lang en_US.UTF-8
keyboard us
selinux --enforcing
firewall --enabled --ssh
rootpw –iscrypted {{ root_password_hash }}
authconfig --enableshadow --passalgo=sha512
timezone --utc --ntpservers {{ ntp_servers|join(',') }} {{ timezone }}
zerombr
clearpart --all
bootloader --location=mbr --timeout=5
part /boot --asprimary --fstype="xfs" --size=1024 --ondisk=sda
part pv.1 --size=1 --grow --ondisk=sda
volgroup {{ hostname }}_system pv.1
logvol / --vgname={{ inventory_hostname }}_system --size=2048 --name=root --fstype=xfs
logvol /usr --vgname={{ inventory_hostname }}_system --size=2048 --name=usr --fstype=xfs
logvol /var --vgname={{ inventory_hostname }}_system --size=2048 --name=var --fstype=xfs
logvol /var/log --vgname={{ inventory_hostname }}_system --size=2048 --name=varlog --fstype=xfs
logvol swap --vgname={{ inventory_hostname }}_system --recommended --name=swap --fstype=swap
network --device=eth0 --bootproto=static --onboot=yes --activate --ip={{ ipv4_address }} --netmask={{ ipv4_netmask }} --gateway={{ ipv4_gateway }} --nameserver={{ dns_servers|join(',') }}
%packages --excludedocs
@Core
vim-enhanced
%endThe Jinja2 engine replaces all the variables enclosed by {{ }} with whichever facts are available for the specified host in the inventory, resulting in a correct kickstart file, assuming all variables have been correctly set.
Jinja2 can do more than just replace variables with whatever is in the inventory. It was originally developed as a rich templating language for web pages and supports major features such as conditions, loops, and so on.
Using Jinja, you can easily loop over a list or array within the inventory and use the resultant variable or even dictionaries and objects. For example, consider that your host has the following fact:
{ 'nics': [
{ 'device': 'eth0', 'ipv4': { 'address':'192.168.0.100', 'netmask':'255.255.255.0','gateway':'192.168.0.1'} },
{ 'device': 'eth1', 'ipv4': { 'address':'192.168.1.100', 'netmask':'255.255.255.0','gateway':'192.168.1.1'} } ] }This would allow you to replace the network portion of your kickstart script with the following:
{% for nic in nics %}
network –device={{ nic.device }} --bootproto=static --onboot=yes --activate --ip={{ nic.ipv4.address }} --netmask={{ nic.ipv4.netmask }} --gateway={{ nic.ipv4.gateway }}
{% endfor %}There is one consideration with provisioning new systems such as this and the inventory: you can only use the facts that you have introduced yourself, not those that Ansible gets from the system. This is because firstly, they don't exist yet, and secondly, the task is executed on a different host.
For more information about templating with Ansible, read the Jinja2 Template Designer documentation at http://jinja.pocoo.org/docs/dev/templates/.
For more information on the Ansible template module, go to http://docs.ansible.com/ansible/template_module.html.
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