xcp-ng / create-install-image

Scripts and files used to generate an XCP-ng installer image

Generation of XCP-ng installation images

The scripts in this repository can be used to generate installation images for XCP-ng. The resulting .iso images can be burnt on a CD/DVD or on a USB-storage device.

Two kind of images are currently supported:

• full image, including all necessary packages, allowing installation without network access
• "netinstall" image, much smaller, which will only allow packages to be fetched from a repository through the network

General notes

Those scripts should be run in the xcp-ng-build-env docker container for reproducibility. Since the base environment is currently based on CentOS 7, many constraints prevent to make it work properly on more recent Linux distros. This base distro is expected to evolve with new XCP-ng versions.

They require to install some additional packages first:

sudo yum install -y genisoimage syslinux grub-tools createrepo_c libfaketime
sudo yum install -y --enablerepo=epel gnupg1

Overview of the generation process

The sequence of steps is:

• mirror: (optionally) create a (partial) local mirror from source repos, using mirror-repos.sh
• installimg: create installer root filesystem from the local mirror or from source repos, using ./scripts/create-installimg.sh
• iso: create XCP-ng installation ISO, from installer root filesystem, from local mirror or source repos, and (optionally) from a signing script, using ./scripts/create-iso.sh

Individual scripts

All script have a --help documenting all their options.

./scripts/create-iso.sh

Creates .iso from:

• install.img (see below)
• yum repository for the product (or a local mirror) for boot files and local repository
• additional files from ./iso/$RELEASE/
• optional signing script

When generating a full image (as opposed to a netinstall one), the yum repository included in the ISO can optionally be signed. Since the signing key is precious and secret material, it is advised not to be stored on a development machine. To perform the signing operation, you have to provide an executable script which will take as parameter the path to the directory with which contents the ISO will be built.

The script must:

• sign the repomd.xml yum repository metadata index using a gpg1 detached ascii/armor signature
• export the public key usable for signature verification to a RPM-GPG-KEY-* file at the root of the ISO directory
• set the [keys]key1 field in .treeinfo at the root of the ISO directory to name the file created at previous step containing the public key

Note

The scripts/sample-sign-script.sh example script is only suitable for playing with a test key. A safer solution would for example request signature from a signature server, prompting you for an OTP token to make sure you're entitled to use the service.

./scripts/create-installimg.sh

Creates install-$RELEASE.img for input to create-iso, from:

• yum repository for the product (or a local mirror)
• a packages.lst file listing RPMs to be installed
• additional files from ./installimg/$RELEASE/

./scripts/mirror-repos.sh

Note this script requires the lftp tool to do its job:

sudo yum install -y --enablerepo=epel lftp

Creates a local mirror of a subset of an official set of repositories for a given XCP-ng version, suitable for building an installation ISO. This scripts excludes from the mirror:

• source RPMs
• development RPMs
• debugging-symbols RPMs
• a few large RPMs only useful as build dependencies: ocaml, golang, java

Repositories to mirror can be specified in 2 ways:

• a XCP-ng version identifier: the relevant subdirectory of https://updates.xcp-ng.org/ will be mirrored under a subdirectory of the target directory named after the version. Eg. this will synchronize the official XCP-ng distribution site to ~/mirrors/xcpng/8.3/:

  ./scripts/mirror-repos.sh 8.3 ~/mirrors/xcpng/
  

• a URL to a browsable directory: the whole tree behind this directory will be mirrored under a subdirectory of the target directory named after the version. Eg. the above is equivalent to:

  ./scripts/mirror-repos.sh https://updates.xcp-ng.org/8/8.3 ~/mirrors/xcpng/
  

Note

this includes much more packages (order of a few gigabytes) than needed for producing the install ISO, notably build-dependencies that are not needed by the installer, and not get installed themselves on the XCP-ng host either. But a local mirror which you control will provide image reproducibility, through the ability to work offline (including reproducibility when the source repo changes between 2 runs, and consistency when it changes between the installimg and iso steps).

Note

this is not a general-purpose mirroring tool. It will notably not mirror a number of development packages, which you would need to build extra software or rebuild packages for XCP-ng. If you need more, use other tools like yum's reposync (which sadly we could not build on, due to its complete lack of filtering features).

Warning

If the script fails with the error message "Cannot assign requested address", you need to configure lftp DNS resolution order to first look for IPv4 addresses by adding this line to ~/.lftprc:

set dns:order "inet inet6"

Configuration layers and package repositories

Configuration layers are defined as a subdirectory of the configs/ directory. Commands are given a layer search path as <base-config>[:<config-overlay>]* .

Standard layers are organized such as two of the standard layers must be used:

• The "version" layer (e.g. 8.2) provides required files:

  • packages.lst and yum.conf.tmpl used to create the install.img filesystem
  • yumdl.conf.tmpl used to download files for the RPM repository included in the ISO

• The "repo" layers (e.g. updates) each provide a yum repo configuration file, and optionally an INCLUDE file to pull additional base repo layers. The base layer will always be in the include chain.

Other recognized config files:

• All layers may provide installer-bootargs.lst, whose contents will be added as installer's dom0 boot parameters. This is notably useful for downstream users to pass no-gpgcheck using their own layer when building a 8.3 ISO, so they can sign their repo metadata with their own key without getting gpgcheck refuse to install RPMs signed by XCP-ng key. repo-gpgcheck is already effective to verify the repo metadata so gpgcheck does no provide any real value here. In 8.2 however this option does not exist (only the answerfile allows to disable gpg checking, and does not separate checking RPMs from repodata).

XCP-ng official repositories are located at https://updates.xcp-ng.org/ and most of them are available through standard "repo" layers; e.g. the testing repository for 8.2 LTS can be used as 8.2:testing.

Custom repositories can be added with --define-repo flag (can be used multiple times to define more than one custom repo). They will be used by yum using the first CUSTOMREPO.tmpl template found in the layer search path (one is provided in base).

Examples

8.3 updates and testing

./scripts/mirror-repos.sh 8.3 ~/mirrors/xcpng

sudo ./scripts/create-installimg.sh \
    --srcurl file://$HOME/mirrors/xcpng/8.3 \
    --output install-8.3.testing.img \
    8.3:testing

./scripts/create-iso.sh \
    --srcurl file://$HOME/mirrors/xcpng/8.3 \
    --output xcp-ng-8.3.testing.iso \
    -V "XCP-NG_830_TEST" \
    8.3:testing install-8.3.testing.img

tip of 8.2 (8.2 + updates)

./scripts/mirror-repos.sh 8.2 ~/mirrors/xcpng

sudo ./scripts/create-installimg.sh \
    --srcurl file://$HOME/mirrors/xcpng/8.2 \
    --output install-8.2.updates.img \
    8.2:updates

./scripts/create-iso.sh \
    --srcurl file://$HOME/mirrors/xcpng/8.2 \
    --output xcp-ng-8.2.updates.iso \
    -V "XCP-NG_82_TEST" \
    8.2:updates install-8.2.updates.img

testing boot modes in qemu

Base command will use PC BIOS:

qemu-system-x86_64 -serial stdio -m 2G

Note that -m 1G is enough to check that the bootloader is properly loaded and runs, but not to boot to the installer TUI.

For UEFI find the OVMF firmware (on Debian: in /usr/share/OVMF/), and add:

 --bios /usr/share/edk2/ovmf/OVMF_CODE.fd

(-net none was found to be sometimes necessary in UEFI mode, for a reason still to be determined)

• boot media selection:

  • CD/DVD:

   -cdrom xcp-ng-install.iso
  

  • USB storage:

   -drive if=none,id=stick,format=raw,file=xcp-ng-install.iso \
   -device nec-usb-xhci,id=xhci \
   -device usb-storage,bus=xhci.0,drive=stick
  

Testing that scripts run correctly

Minimal tests to generate install ISO for a few important configurations are available in tests/. They require one-time initialization of the tests/sharness/ submodule:

git submodule update --init tests/sharness/

They require setting a variable pointing to the repositories to be used; it is recommended you use a local mirror for this.

Two common ways of running the tests are:

• just using make, which produce human-readable TAP output:

  make -C tests/ XCPTEST_REPOROOT=file:///data/mirrors/xcpng
  

• through prove (in package perl-Test-Harness in CentOS/Fedora/RHEL, in perl for the rest of the world), which provides both options for e.g. parallel running, and global summary:

  XCPTEST_REPOROOT=file:///data/mirrors/xcpng prove tests/
  

The tests for producing install.img are tagged as expensive and not run by default, to run them you must pass the -l flag to the test script, which can be achieved respectively by:

make TEST_OPTS="-l"

prove tests/ :: -l