VMware vSphere PowerCLI Reference. Graf Brian

is the infrastructure required to perform a PXE-based installation. Though not extreme, it is still overkill for small/medium environments. We consider PXE a minimum requirement for any environment with more than 10 hosts.

      Gathering Required Software

      We’re going to make the assumption that, since you’re reading a PowerCLI book, your management station is a Windows PC. Therefore, the following requirements apply:

      CD/DVD For a CD/DVD installation, you will need an ISO Image editing tool such as ImgBurn, available for download from www.imgburn.com/.

      Thumb Drive/USB Key For a thumb drive/USB key installation, you’ll need UNetbootin, available from http://unetbootin.sourceforge.net/.

      PXE A multitude of PXE implementations are available, most of them based on Linux. That said, we recommend you use what you’re comfortable with, and if you have no comfort zone, we recommend Carl Thijssen’s Ultimate Deployment Appliance (UDA), available from www.ultimatedeployment.org/.

      Automate an Installation

      Automating a vSphere installation can mean many different things. At its core, it means you have a zero-touch installation. As you learned earlier, this can be accomplished regardless of the media you choose. You will, however, outgrow this minimal automation solution very quickly, as it doesn’t help solve the bigger problem of host configuration. To resolve that issue, you must first answer one simple, multiple-choice question.

      Are you more comfortable using:

      1. BusyBox/Python

      2. PowerCLI

      3. Host profiles

      4. All of the above

      If you chose option A, you will want to try to do as much as possible with the first boot and postinstall sections within Kickstart – but you will find you cannot do everything. The advantage of option A is that there are no external requirements. This is a great solution for small environments. If you have the time and skill set to configure a vSphere host via BusyBox/Python, it is possible to automate just about every aspect of vSphere.

      TIP Although this looks and feels very similar to a traditional Linux Kickstart, it’s not! Do not assume that because something works in Linux Kickstart that it will work with vSphere.

      If you chose option B, you will want to configure the bare minimum via Kickstart. Most likely, you’ll configure the management vmknic and partition assignment. That said, it is exponentially easier to perform some actions, like password and license assignment, from Kickstart.

      If you chose option C, you undoubtedly have Enterprise+ licensing and want to use this advanced feature. Unfortunately, there are some things that you cannot do using host profiles (see Chapter 5, “Using Advanced vSphere Features,” for more information). Host profiles do offer a compelling capability – compliance. Anything that can be done via host profiles should be done via host profiles, because they will ensure that your hosts continue to be configured correctly.

      If you haven’t figured it out already, option D is the best answer. You should use a combination of all three, assuming you have sufficient licensing to use host profiles. There are some aspects of vSphere configuration that are just easier to do while loading the host. Some matters are best left to host profiles. PowerCLI is the glue in all this that will bridge these two disparate worlds. If host profiles are off the table, take the path of least resistance and use both Kickstart and PowerCLI.

      Customizing an Installation with Kickstart

As of ESXi 4.1, VMware supports a scripted installation mode: Kickstart. Kickstart is a configuration file that the installer reads in and then uses to perform a silent installation. Exploring the full set of options and capabilities of the Kickstart configuration file is beyond the scope of this book, but we will go over the basics, starting with how to have a non-interactive installation from the CD/DVD and USB installation mediums (see Listing 2-7).

Listing 2-7: A Kickstart configuration for non-interactive installation

      TIP Refer to the VMware documentation and knowledge base for full information about all of the possible commands and options that can be used as a part of the Kickstart process.

Using a USB key for the installation media makes including Kickstart files incredibly easy. Simply create a directory in the root of the drive and place the file there. Figure 2-1 shows the file structure of the install media after it has been loaded. This USB device was created by taking a customized ISO and leveraging UNetbootin to copy the media to the drive.

      Notice in Figure 2-1 that a folder named kickstarts was created at the root of the device. Simply copy any Kickstart files to that folder location, but don’t forget their names! After booting to the USB device you will need to specify the Kickstart location at the boot loader prompt.

Figure 2-1: USB installation media file layout

Figure 2-2 shows the host after booting to the USB media. When the boot menu screen is displayed, press any key to interrupt the process. Press the Tab key to edit the boot options for your device and append ks=usb:/kickstarts/ks.cfg, where ks.cfg is the name of your Kickstart file. Once you provide the path to your Kickstart file (Figure 2-3), simply press Enter and go get a cup of coffee (but don’t bring it in the datacenter!).

Figure 2-2: Host boot screen

Figure 2-3: Boot configuration customization

If this is too much effort for you, you can edit the file ISOLINUX.CFG in the root of your USB media. Find the line under the “LABEL install” section that contains the APPEND descriptor and append the same text we used earlier. Listing 2-8 shows what the file should look like after editing.

Listing 2-8: A completely hands-off ISOLINUX.CFG

      Postinstallation Configuration

      As we indicated earlier, you have several options for postinstallation configuration. They all fall into one of two categories: online or stand-alone. An example of a stand-alone installation is the traditional monolithic Kickstart.

      A stand-alone installation should only be used in scenarios where the network connectivity cannot be assumed. In such an install, all the postconfiguration tasks must be handled via the Kickstart %post and %firstboot scripts. This is neither easy nor recommended, but under certain conditions, it is the only way to automate all parts of installation. For instance, when you port-channel all network connections to your host, it will not be able to connect to the network until the load-balance configuration has been done on the vSwitch. Because this is a prerequisite for network connectivity, it cannot be done remotely.

As shown in Listing 2-9, you can use a script as the %post section of a Kickstart configuration file. This two-line script adds a second NIC to the standard vSwitch and enables an IP hash load-balancing