Lars Karlitski 64713449ce Introduce runners

We've been using a generic `osbuild-run`, which sets up the build
environment (and works around bugs) for all build roots. It is already
getting unwieldy, because it tries to detect the OS for some things it
configures. It's also about to cause problems for RHEL, which doesn't
currently support a python3 shebang without having /etc around.

This patch changes the `build` key in a pipeline to not be a pipeline
itself, but an object with `runner` and `pipeline` keys. `pipeline` is
the build pipeline, as before. `runner` is the name of the runner to
use. Runners are programs in the `runners` subdirectory.

Three runners are included in this patch. They're copies of osbuild-run
for now (except some additions for rhel82). The idea is that each of
them only contains the minimal setup code necessary for an OS, and that
we can review what's needed when updating a build root.

Also modify the `--build-pipeline` command line switch to accept such a
build object (instead of a pipeline) and rename it accordingly, to
`--build-env`.

Correspondingly, `OSBUILD_TEST_BUILD_PIPELINE` → `OSBUILD_TEST_BUILD_ENV`.

2019-11-25 13:05:22 +01:00

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osbuild

A build system for operating system images, working towards an image build pipeline that's more comprehensible, reproducible, and extendable.

Pipelines

The build process for an image is described by a pipeline. Each stage in a pipeline is a program that, given some configuration, modifies a file system tree. Finally, an assembler takes a filesystem tree, and assembles it into an image. Pipelines are defined as JSON files like this one:

{
  "name": "Example Image",
  "stages": [
    {
      "name": "org.osbuild.dnf",
      "options": {
        "releasever": "30",
        "basearch": "x86_64",
        "repos": [
          {
            "metalink": "https://mirrors.fedoraproject.org/metalink?repo=fedora-$releasever&arch=$basearch",
            "checksum": "sha256:9f596e18f585bee30ac41c11fb11a83ed6b11d5b341c1cb56ca4015d7717cb97",
            "gpgkey": "-----BEGIN PGP PUBLIC KEY BLOCK-----\n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\n=BfZ/\n-----END PGP PUBLIC KEY BLOCK-----\n"
          }
        ],
        "packages": [ "@Core", "grub2-pc", "httpd" ]
        }
    },
    {
      "name": "org.osbuild.systemd",
      "options": {
        "enabled_services": [ "httpd" ]
      }
    },
    {
      "name": "org.osbuild.grub2",
      "options": {
        "root_fs_uuid": "76a22bf4-f153-4541-b6c7-0332c0dfaeac"
      }
    }
  ],
  "assembler": {
    "name": "org.osbuild.qemu",
    "options": {
      "format": "qcow2",
      "filename": "example.qcow2",
      "ptuuid": "0x7e83a7ba",
      "root_fs_uuid": "76a22bf4-f153-4541-b6c7-0332c0dfaeac",
      "size": 3221225472
    }
  }
}

osbuild runs each of the stages in turn, isolating them from the host and from each other, with the exception that they all operate on the same filesystem-tree. The assembler is similarly isolated, and given the same tree, in read-only mode and assembles it into an image without altering its contents.

The filesystem tree produced by the final stage of a pipeline, is named and optionally saved to be reused as the base for future pipelines.

Each stage is passed the (appended) options object as JSON over stdin.

The above pipeline has no base and produces a qcow2 image.

Running

usage: __main__.py [-h] [--build-env ENV] [--store DIRECTORY] [-l DIRECTORY]
                   [--json]
                   PIPELINE

Build operating system images

positional arguments:
  PIPELINE              json file containing the pipeline that should be
                        built, or a '-' to read from stdin

optional arguments:
  -h, --help            show this help message and exit
  --build-env ENV       json file containing a description of the build
                        environment
  --store DIRECTORY     the directory where intermediary os trees are stored
  -l DIRECTORY, --libdir DIRECTORY
                        the directory containing stages, assemblers, and the
                        osbuild library
  --json                output results in JSON format

Running example

You can build basic qcow2 image of Fedora 30 by running a following command:

sudo python3 -m osbuild --libdir . samples/base-qcow2.json

Root rights are required because osbuild heavily relies on creating systemd containers and bind mounting.

It shouldn't interfere with host OS but please be careful! It's still under development!
--libdir argument is required because osbuild expects itself to be installed in directories under /usr. Using this argument you can change the expected path.
You don't need to use any kind of virtual environment, modern version of Python 3 is enough. osbuild uses only standard library and linux commands.

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osbuild

Pipelines

Running

Running example

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