.chezmoiroot as template to include large common dotfiles

[RangHo]

Is your feature request related to a problem? Please describe.

I am using Arch Linux with Niri on my desktop and Void Linux with Xmonad on my laptop.
Due to the difference in display management system (X11 vs. Wayland), I have many dotfiles specific for each system, but I still have a ton of dotfiles shared across all systems.

For example, I use different application launcher and notification daemon on my desktop and laptop, but I still use Bash, Fish, Vim, Emacs, Ghostty, wallpapers, Git settings, templates, etc...

Reconciling for the difference is possible now, but it requires carefully reading and making sure that .chezmoiignore is correct in all cases. It is working for now, but the difference would just keep getting larger as I move away from my X11-based locker setup on my desktop, and I'd be banging my head against the .chezmoiignore file after finding 1852nd typo that breaks the system.

Describe the solution you'd like

Maybe we can put multiple roots in .chezmoiroot and make the file a template. For example,

common
{{- if eq .chezmoi.hostname "my-desktop" }}
desktop
{{- else if eq .chezmoi.hostname "my-laptop" }}
laptop
{{- else }}
# Maybe this is a server that needs no GUI-related stuff :)
{{- end }}

If there are any conflicts between among dotfiles, the ones specified later in .chezmoiroot always preferred, including the directories with +exact attributes.

Describe alternatives you've considered

Putting everything in .chezmoiignore is for now the only solution, I imagine.

Additional context

My dotfile repository is here. I recently moved to Chezmoi from GNU Stow-based approach, and this is the feature I'm missing the most from Stow.

I've seen a discussion at #3083, but it seems to refer to a system where completely different operating system is used. I thought this issue was different enough to deserve its own feature request.

[halostatue]

Consider using .chezmoiignore which is templatable:

{{ if neq .chezmoi.hostname "my-desktop" }}
{{/* Add all the stuff that should be ignored if it *isn't* my-desktop */}}
{{ end }}

{{ if neq .chezmoi.hostname "my-laptop" }}
{{/* Add all the stuff that should be ignored if it *isn't* my-laptop */}}
{{ end }}

[twpayne]

Maybe we can put multiple roots in .chezmoiroot and make the file a template.

See also https://www.chezmoi.io/user-guide/frequently-asked-questions/design/#can-chezmoi-support-multiple-sources-or-multiple-source-states.

[Lockszmith-GH]

I have multiple chezmoi roots in my repo.

Unless what you're asking for is dynamically changing your home folder content constantly, I presume the choice needs to be done once and then stick to it.

The way I solved it is by having an run_onchage_init in the root of the repo, that writes .chezmoiroot and then restarts the init --apply process - this time in the new root. So this script runs only one time, during first apply following the first 'fresh' init.

Below is a stripped down walk through of my implementation (full repo link)

.chezmoiscripts/run_onchage_init.ps1.tmpl # Template determines whether content is POSIX with she-bang, extension allow it to run as PowerShell on windows.
.gitignore
chezmoi-roots/
+-- __root.links/
|   +-- chezmoiroot.system1
|   +-- chezmoiroot.system2
+-- system1/
|   +-- .chezmoi.toml.tmpl # this is the config template for system 1
|   +-- [system 1's content]
+-- system2/
    +-- .chezmoi.toml.tmpl # this is the config template for system 2
    +-- [system 2's content]

.gitignore content:

# .chezmoiroot is generated by .chezmoiscripts/run_onchage_init.ps1.tmpl
# during chezmoi init --apply
.chezmoiroot

chezmoi.roots/__root.links/chezmoiroot.system1 content:

chezmoi-roots/system1

chezmoi.roots/__root.links/chezmoiroot.system2 content:

chezmoi-roots/system2

.chezmoiscripts/run_onchage_init.ps1.tmpl code:

{{- if ne .chezmoi.os "windows" -}}
#! /usr/bin/env bash

set -e
ln -s "chezmoi.roots/__root_links/system1.chezmoiroot" .chezmoiroot
# or just plain:
cp "chezmoi.roots/__root_links/system1.chezmoiroot" .chezmoiroot

# restart chezmoi init, after nuking the local chezmoi state
# exec sh = replace script process by init session - this actually kill the running chezmoi process that called the script.
# rm boltdb = nuke 'short-lived' init chezmoi config
# chezmoi init = intialize, now with .chezmoiroot in place
# chezmoi apply
# exec $SHELL
PATH="$HOME/bin:$PATH" exec sh -c 'rm ~/.config/chezmoi/chezmoistate.boltdb \
    && chezmoi init && chezmoi apply && exec $SHELL -l
    '
{{- else -}}
# PowerShell code to initialize on Windows:

$local:CZROOTLINK=Join-Path "chezmoi.roots" (Join-Path "__root_links" "chezmoiroot")
$local:CZ_ROOT_LINK=(Join-Path $env:CHEZMOI_SOURCE_DIR "$CZROOTLINK")
$CZ_ROOT_LINK = "${CZ_ROOT_LINK}.system2"

$local:newItem = [ordered]@{
    Type = "File"
    Path = $env:CHEZMOI_SOURCE_DIR 

    Name = ".chezmoiroot"
    Value = (Get-Content -LiteralPath $CZ_ROOT_LINK).Replace('\', '/')
}
$null = New-Item @newItem -ErrorAction Stop

# no 'exec' like action for Power Shell, so need to have user perofrm the step:
Remove-Item ~/.config/chezmoi/chezmoistate.boltdb

Write-Host -ForegroundColor Green (
    ".chezmoiroot initialized. You will need to remove:",
    "    ~/.config/chezmoi/chezmoistate.boltdb",
    "and then",
    "    run chezmoi init --apply again",
    "(the commands are already in your clipboard)." -join "`n"
    )
"Remove-Item ~/.config/chezmoi/chezmoistate.boltdb; chezmoi init --apply" | Set-Clipboard

{{- end -}}

It works, and it works well. I also have a small script that initializes chezmoi and reruns it all, in case I need to switch (development / testing)

It's not 'simple', but it works seamlessly, and it only requires interaction once per environment.
You can ditch the __root.links sub folder and have the script manage it completely, these are all design choices you'll need to make.

Hope this helps.