keg-recipes

This repository contains recipes that can be used to generate various kiwi image descriptions using keg.

The "released" branch reflects the image descriptions as they are used to build images maintained and published by SUSE. Details about how changes are applied are provided in CONTRIBUTING.md

Basics

Keg recipes contain three types of input data, the image recipe in the images sub directory, the image data in the data sub directory, and the schema definition in the schemas sub directory. The recipe and data configuration is in YAML format, the schemas are Jinja2 templates.

The schema defines the structure of the output, namely the kiwi configuration file and setup script. The configuration data used by the schema is collected by keg from the image recipe and the data bits referenced by the recipe.

Keg merges the input data in a way that allows to mix and match configuration bits to create a specific image description. This can be used to create a large number of different image descriptions based on the input configuration without the need to edit them directly.

Structure

Image recipes

A recipe defines the image's base parameters and one or more build profiles. Any leaf directory under image acts as the input parameter for keg. Keg will read any YAML file in that directory and merge it with all YAML files of its parent directories. This allows to e.g. define global defaults in the top level directory, product specific defaults in a directory below that, and all bits unique to the image in the leaf directories.

Image data

The data sub directory contains sets of parameters that form logical blocks of configuration data. The base sub directory contains blocks for building the OS base of the image. The csp sub directory contains blocks for adding support for a specific cloud framework. The products sub directory contains blocks for building a product on top of the OS base, e.g. SUSE Manager.

The data files get merged in a similar way as the image recipe files, but keg may scan additional sub directories based on the include-suffix parameter of the image recipe, and this applies to all parent directories as well. This can be used to add OS version specific changes to the generic configuration.

To visualize how this works in practice, let's look at the configuration sets for EC2 support. A recipe for a SLES 15 SP2 EC2 image may contain the following configuration parameters:

include-prefix: sle15/sp2
profile:
  EC2-HVM:
    include:
      - csp/ec2/ondemand

This will result in keg scanning the following directories for input files:

data/csp/ec2/ondemand/sle15/sp2
data/csp/ec2/ondemand/sle15
data/csp/ec2/ondemand
data/csp/ec2/sle15/sp2
data/csp/ec2/sle15
data/csp/ec2
data/csp/sle15/sp2
data/csp/sle15
data/csp
data/sle15/sp2
data/sle15
data

This may pick up the following files:

data/csp/profile_defaults.yaml
data/csp/ec2/profile.yaml
data/csp/ec2/sle15/packages.yaml
data/csp/ec2/ondemand/sle15/packages.yaml

And thus use the global profile defaults for all CSPs, the EC2 specific default profile, the SLES 15 set of EC2 specific packages, and the additional SLES 15 packages required for on-demand functionality.