preseeder

preseeder

preseeder helps automate Ubuntu & Debian installations by templating preseed.cfg files and serving them (and other assets) to the Debian (or Ubuntu) installer over http.

There are three reasons you might find this useful:

1. It simplifies writing a preseed.cfg.

   The arguments in a preseed.cfg file are not always easy to test or understand. preseeder moves the important ones into their own config file and lets you render the rest, either using preseeder's "known good" template or your own.

2. It simplifies loading a post-installation script or other assets.

   To get a fully configured installation from boot, one typically needs to run a lot of stuff in the so-called late_command in preseed.cfg. Unfortunately, it's hardly ideal to cram it all into the config file. preseeder simplifies this by letting you serve an arbitrarily long late_command (and any other static assets). It will also take care of automatically adding any SSH keys to /root/.ssh/authorized_keys as part of late_command execution.

3. For installing a small number of servers, it's fewer dependencies and easier to set up than a large-scale solution.

   If you need to maintain hundreds of PXE-booted servers, something like Cobbler is the way to go. But, if you just want to automate bare-metal provisioning, this may be a good way to go. (Of course, for PXE, you'll still need to configure your DHCP server and set up a TFTP server.)

Setup

To install, just do:

go install github.com/hblanks/preseeder

Usage

See preseeder -h. The most important thing you'll need is a preseed.yaml file. See examples/ for two examples.

Two other really useful options are -i to specify RSA public keys (typically you'll just do -i ~/.ssh/id_rsa.pub) and -x to specify a shell script to execute after booting.

Finally, it's often helpful to serve static files from your preseeder. Yes, you can do that, too, with -s.

Quickstart

Step 1: Configure DHCP and TFTP for network booting.

See examples/tftpboot/README.md for suggestions on setting this up, if you're not already familiar. The key is to specify a preseed URL of http://{$YOUR_IP:8080}/preseed, or whatever port it is you're using.

If you really don't want to network boot, you could always boot off of some other media and type the preseed URL into the boot prompt of every server...but what's the fun in that?

Step 2: Install and start the preseeder

Assuming you're fine with the example, you can just do:

go install github.com/hblanks/preseeder
preseeder -i ~/.ssh/id_rsa.pub examples/preseed.yaml

Part 3: boot

Configuring PXE boot is BIOS-specific, but F8 usually does the trick.

You'll be able to view a JSON dump of events at http://{$YOUR_IP}:8080/.