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Generating an iso file

In the last chapter we built some raptor layers that serve as the file content for the bootable iso we want to build.

These layers are very similar to layers in a docker file1.

After building ssh (which implies the base target), their respective contents can be found in layers/....

Once built like this, it’s possible to “run” the container, like so:

$ sudo raptor run ssh id
[*] Completed [675DE2C3A4D8CD82] index.docker.io-library-debian-trixie
[*] Completed [AB1DD71BFD07718B] base
[*] Completed [80E4F4E5B0E2F6BA] ssh
uid=0(root) gid=0(root) groups=0(root)

Instead of id, an interactive command like sh or bash could be specified. This is very similar to how docker run works, except raptor containers are ephemeral by default. If no further options are specified, any changes made to the container will only be saved while the container is running.

This is all well and good, but we are interested in building a bootable iso from the layers, not just running them as a container.

It turns out that having a stack of layers available, is quite a powerful primitive. With the right commands, we could build all kinds of output from them; a .tar.gz file with a release archive, a bootable iso, or even a disk image for a machine.

In other words, the same input layers can be post-processed into a wide variety of output layers, depending on what you need.

To help get started with this, Raptor provides a standard set of build containers, in the companion project raptor-builders:

  • [deblive] Builds Debian liveboot isos from Raptor layers.
  • [disk-image] Builds disk images (for virtual or physical machines) from Raptor layers.

Build containers

Raptor build containers are just regular Raptor containers, that are configured to expect an input, and produce an output.

The containers from the raptor-builders project are available to anyone, but are not “built in” to Raptor - they don’t use any special features or private APIs. Anyone can make build containers that are similar (or even identical to) raptor-builders.

Since this walkthrough is focused on making a liveboot iso, we’ll use the deblive builder to convert layers to an iso file.

First, we need to clone (or otherwise download) the raptor-builders project:

git clone https://github.com/chrivers/raptor-builders

This builder uses mounts to access input, output and cache from outside the container (see MOUNT).

To build the layers from the last step into a debian liveboot iso, use the following command (assuming raptor-builders is checked out next to the directory containing ssh.rapt):

sudo raptor run                \
  -L book   book/example       \
  -L rbuild ../raptor-builders \
  -C liveboot-cache            \
  -I '$book.ssh'               \
  -O custom-liveboot.iso       \
  '$rbuild.deblive'

Tip

The command above uses the short-form command line options typically used interactively. Long-form options are also available, if greater clarity is desired (e.g. for scripting purposes).

sudo raptor run                    \
  --link book   book/example       \
  --link rbuild ../raptor-builders \
  --cache liveboot-cache           \
  --input '$book.ssh'              \
  --output custom-liveboot.iso     \
  '$rbuild.deblive'

(See the section on module names to learn more about --link and the $rbuild notation.)

This build process works, but the required command is fairly long and complicated.

In the next chapter, we’ll take a look at raptor-make, and how it can simplify the process.

  1. There’s a key difference between how Raptor and Docker handles layers. In Docker, each command (RUN, COPY, etc) creates a new layer. In Raptor, each .rapt file forms a new layer. ↩