Discussion/Feature Request: Easy way to add patches

[xrobau]

Currently I use a pre-build hook to add some patches to the builder. One of the most annoying ones is that they removed qemu-agent for some reason recently (not sure if it's been fixed in the latest builder), so I have a build environment that looks like this:

vyos_bld@debbuild:~$ ls
50-qemu-agent.chroot  50-zerotier.chroot prehook.sh  vyos-jenkins
vyos_bld@debbuild:~$ cat prehook.sh
#!/bin/bash
#

mkdir -p ~/vyos-jenkins/patches
cp ~/50* ~/vyos-jenkins/patches/
chmod -R 755 ~/vyos-jenkins/patches
cp ~/vyos-jenkins/patches/* data/live-build-config/hooks/live/
ls -al ~/vyos-jenkins/patches/* data/live-build-config/hooks/live/

vyos_bld@debbuild:~$

Do you think it's worthwhile updating image_builder.py to sync anything found in patches into live-build-config? Obviously it would have to be a bit smarter than just a copy, because a patch might want to add sources or other things, not just hooks.

I'm happy to spend the time if you think it would be useful. For example, zerotier 1.14.1 is now GPL'ed and can be included without violating any licences.

[dd010101]

The generic.toml is meant for arbitrary machine and not any specific hypervisor, that's why the qemu-guest-agent was removed and they instead created different .toml flavors as alternate images for specific hypervisors. It's a decision to go from single universal image to specific set of images.

If you look at this flavor as example - https://github.com/NOTvyos/vyos-build/blob/circinus/data/build-flavors/xcpng.toml
In the readme you can see how to add arbitrary files - https://github.com/NOTvyos/vyos-build/tree/circinus/data/build-flavors

It's not as powerful as full control of live-build with hooks into any stage, but for many applications - it's good enough.

If you want to use custom flavor, then you need specify the flavor such as "generic" as positional argument if you use build-vyos-image directly or via --flavor "generic" option if you use image_builder.py. This doesn't solve the issue that you need to modify vyos-build, so you still need to fork vyos-build and build using your fork or use --pre-build-hook to modify vyos-build right before build as you already do.

There is also easier way how to add just packages - by using the --custom-package of build-vyos-image, or with image_builder.py you can use --extra-options "--custom-package qemu-guest-agent". But, yeah, if you want also custom files then you need the custom .toml flavor and if you want to execute arbitrarily script inside the chroot of the image at specific stage then live-build hooks is the only way.

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As you see there are multiple options before you need to use live-build hooks, so I don't think the live-build integration is essential, it's not exactly straightforward to use anyway - you still need to know live-build and what hooks get executed when and where, so it isn't user-friendly and that's why the other options exist. Given this - if you already know live-build and want full live-build control, then the fact you need to use custom vyos-build fork or --pre-build-hook seems like minor detail.