Migrating Kickstart from CentOS 6 to CentOS 7 + ESXi VMware Tools

In another post I described how to install CentOS 6 via a kickstart file (be sure to check out the “Kickstart Sample Configuration” section). CentOS 7 was recently released, and with that I needed to also use a kickstart configuration. However, simply using the previous kickstart configuration was not as easy as copy-and-paste (besides updating the release version in the repository configuration).

Summary of Kickstart Changes

There were a few changes that needed to be made for a base/core installation of CentOS 7:

  • Include  eula --agreed (read the documentation)
  • Include  services --enabled=NetworkManager,sshd (read the documentation)
  • Update the install packages list ( %packages  section)
  • CentOS 7 is also a bit more strict with the kickstart file, so I had to explicitly include %end  where applicable
  • CentOS 7’s default file system is now xfs, in CentOS 6 it was ext4, so consider updating the automatic partitioning to use xfs
  • Package groups @scalable-file-systems, @server-platform, @server-policy, and @system-admin-tools no longer exist – I haven’t located suitable replacements yet
  • Things like ifconfig are no longer included by default (they are now deprecated), so if you need them be sure to include net-tools. You should be using ip by now anyway.

Kickstart Sample Configuration

And now, an updated kickstart config for CentOS 7, with consideration of the previously mentioned updates (compare it with the previous Kickstart Sample Configuration mentioned in the other post). I also chose to include some extra packages that don’t exist by default with a @core  installation.

 

VMware Tools Change

If you’re like me and use ESXi, I’m currently on version 5.5 and 5.5u1, the installable tools for integrating with ESXi is a nice treat. However, the repository location has changed specifically for RHEL7, and so have the packages.

Add VMware Tools to YUM

Put the following repo configuration in /etc/yum.repos.d/vmware-tools.repo:

Then update yum and install the tools:

 

 

Install CentOS 6 with Anaconda/Kickstart (plus ESXi VMware Tools)

Synopsis

I’ve been getting my feet wet with ESXi, CentOS 6 VMs, and YUM/RPM. Well the last two I have been using for years, but not like recently.

The goal is to be able to blindly install a controlled distribution of CentOS 6.x quickly and without error (maybe even install multiple at the same time). What I needed:

  • Anaconda Kickstart file (ks.cfg)
  • Local mirrored repository for CentOS 6.x (6.3 in my example)
  • Custom 3rd party repo
  • HTTP/NFS/RSYNC access to these
  • Variable disk/cpu/ram size – the partitions need to be dynamic

Without writing a book about all of this, I really want to just highlight some problems I ran into and how I solved them.

An example of my kickstart file is below for reference.

Automated Partition Schema

Since I’m in the world of virtualized hardware, it is important for the disk to scale easily without lost data. The prerequisite to this is of course Logical Volume Management (LVM). Now you may not agree with my LVM layout, and honestly, this isn’t my expertise (optimization of disk partitions), but at the least there must be “boot,” “root,” and “swap” partitions.

The goal here is to make the root partition grow to its maximum size without negating the swap. Also, the boot partition won’t be on the LVM, it will be fixed in the MBR. The kickstart section is as follows:

I do want to note that the logvol’s are interpreted in a random order, so it is perfectly fine for the swap logvol to be declared after the root (/) logical volume.

Bypassing “Storage Device Warning”

The only problem I had in regards to a prompt-less install was the “Storage Device Warning” asking if I was sure I wanted to write to the disk and lose all of my data. No matter what I put in the partition specification of kickstart, it would always prompt. The answer is to use zerombr yes. See the option “zerombr” as defined within the CentOS kickstart guide. This can be placed anywhere in the kickstarter file (well except in %packages, %post or similar); just put it up near the top.

Auto Reboot

After the installation is complete, automatically reboot the machine. This works perfectly in ESXi since it automatically unmounts the virtual cdrom after the first boot of the guest! Simply put  reboot anywhere in your kickstart – near the top is probably best.

VMware Tools RPM

In order for the vSphere Client to monitor and execute certain tasks on the guest vm, VMware Tools is required. This will show you things like IP addresses, hostnames and guest state as well as integrated shutdown/reboot tools.

Add VMware Tools to YUM

Put the following repo configuration in /etc/yum.repos.d/vmware-tools.repo:

Then execute the following shell in %post of kickstart:

The important part to mention here is that the package is called vmware-tools-plugins-guestInfo. All the dependencies will come with it, so no worries there.

Mirroring a Repository for NFS Kickstart Installation

Create the Repo Mirror

Remember, my goal is to be able to quickly add a CentOS VM. With that, I don’t want to wait 30 minutes to pull down packages from a mirror in Iowa, New York or Cali. I want to pull it down once, keep it up-to-date and have my local install pull from my local mirror. For simplicities sake, I’ll put the mirror in /repo/centos.

I am choosing to exclude any local files/directories (“local*”) and also the huge DVD ISOs (“isos”). Also note that the mirror format is host::path and that the mirror host must support the rsync protocol.

Keep the Local Mirror Updated

To keep the local repo copy up-to-date, run this script via cron (by the way, I stole this from somewhere, I just don’t remember). Please don’t forget to swap out the mirror hostname and path with something that makes more geographical sense to you.

Configure NFS for Kickstart Network Installations

NFS server support is built into CentOS and running by default, so this is pretty easy. Add the following to /etc/exports:

This exports the directory “/repo/centos” for NFS. Only the subnet 172.16.0.0/16 is allowed access (no credentials required). It is mounted as read-only (ro), connection are synchronous as opposed to asynchronous (sync), and all connections are anonymous for security purposes (all_squash). Man exports(5) if you need more help.

Restart NFS via  service nfs restart.

I feel like I’m missing something with NFS, but I don’t recall; this was too easy. In my memory there was a struggle with rpc!

Update iptables for NFS

Edit /etc/sysconfig/iptables and throw these rules in there before -A INPUT -j REJECT --reject-with icmp-host-prohibited.

And restart iptables via  service iptables restart.

Configure Kickstart to Use Local Repo via NFS

This is an easy one-line if everything is set up correctly. Add the following after the “install” option within the kickstart configuration.

Use Local Repo Post Install

So you want to keep using your new local repo beyond the kickstart installation? No worries. Install apache, configure the vhost and update ks.cfg.

Inside vhosts.conf:

Add the following rule to iptables:

Restart iptables via service iptables restart;.

Start httpd via  service httpd start; chkconfig httpd on;.

Update the kickstart configuration:

Done!

Kickstart Sample Configuration

For the option “rootpw” use grub-crypt  with the specified hash algorithm under authconfig –passalgo=X (to replace DEFAULT_SALTED_ROOT_PASSWORD). In the sample ks.cfg file, I have sha512, so:

Using the Kickstart Configuration

The idea is to create a custom ISO with the kickstart configuration embedded, but I haven’t done this yet. So for now, I’m hosting the file as ks.cfg on an intranet HTTP server and booting a centos 6.3 netinstall (~200mb). At the bootloader prompt, specify extra parameters vmlinux initrd=initrd.img ks=http://some.host.local/ks.cfg. This installs all the packages, updates as needed, partitions the disk, runs a custom script, and reboots the machine.

Brain dump complete.