* Update attribute names in code examples (* -> settings.*).
* Use `nix-shell -p` rather than `nix run` because the example won't
work with the current default Nix.
* Update config values for `element-web`.
* Fix link to `element-web` security considerations.
* Make the synapse expression even smaller and use callout-lists to
explain the code.
* Document how to correctly deploy the shared registration secret.
[1] https://spec.matrix.org/latest/client-server-api/#getwell-knownmatrixclient
Potential use cases for disabling `useDefaultFilesystems` include:
- Testing with uncommon filesystem layouts
- Testing scenarios where swapping occurs
- Testing with LUKS-encrypted disks
Closes#177963
Running `nixos/tests/keepassxc.nix` shows:
```
machine # [ 18.705390] xsession[985]: /nix/store/2g2jx5c6x3p152wbiijr0rmky7byqivc-xsession: line 13: nn: command not found
```
This garbled bash script runs without `set -o errexit` and thus skips
"\n\n" as invalid command:
```
$ cat -n /nix/store/2g2jx5c6x3p152wbiijr0rmky7byqivc-xsession
...
\n\n
if [ -e $HOME/.background-image ]; then
/nix/store/wq1d1ph8wj4alpx78akvpbd0a0m9qkd1-feh-3.8/bin/feh --bg-scale $HOME/.background-image
fi
...
```
KeePassXC uses it through
`nixos/modules/services/x11/display-managers/default.nix`:
```
...
# Script responsible for starting the window manager and the desktop manager.
xsession = dm: wm: pkgs.writeScript "xsession" ''
#! ${pkgs.bash}/bin/bash
# Legacy session script used to construct .desktop files from
# `services.xserver.displayManager.session` entries. Called from
# `sessionWrapper`.
# Start the window manager.
${wm.start}
# Start the desktop manager.
${dm.start}
...
'';
...
```
The bogus line was introduced in PR #160752:
```
commit 0bc0dc8090
Author: Shaw Vrana <shaw@vranix.com>
Date: Fri Feb 18 11:27:42 2022 -0800
desktop manager script: start properly
Adds a missing line feed when X is enabled to the start script name
and the appended if check. Resolves#160735
```
I have not tried to reproduce the original issue and thus don't know
why "\n\n" apparently gets interpreted fine in one place but remains
literal the `xsession` case.
However, using a literal newline must be valid for all cases and
certainly fixes the warning seen in KeePassXC tests.
Furthermore, starting the nix string (`''`) with a newline as usual also
fixes its overall indentation.
Seems silly to install this for use with the local server, but to not
configure it to use the local server. Otherwise, out of the box we
just get an error about no server being configured.
The `nixos-rebuild` tool calls `get-version-suffix` to figure out the
git revision of the nixpkgs directory if there is a .git.
https://nvd.nist.gov/vuln/detail/CVE-2022-24765 made git throw an
error if the .git search logic is not turned off and a user
tries to access a `.git` directory they don’t own (otherwise a
different user could trick them into setting arbitrary git config).
So from now on we should always explicitely set `--git-dir`, which
turns this search logic (and thus the security check) off.
It was never meant to be used for anything other than testing
and setting it globally can cause weird loops in GTK-based portals,
where the portal will end up waiting for itself until it times out.
https://github.com/NixOS/nixpkgs/issues/135898
Or it can mess up fonts:
https://github.com/NixOS/nixpkgs/issues/155291#issuecomment-1166199585
Having the option in NixOS makes it look like it is okay or even
desirable to enable, when in fact it is a hack that can subtly break apps.
Some apps allow opting into using portal-based APIs, e.g. for Firefox,
you can set `widget.use-xdg-desktop-portal.file-picker` to `1` in about:config.
Otherwise, you can set the `GTK_USE_PORTAL` environment variable to 1
for individual apps.
People who really want it and aware of the downsides can just set
`environment.sessionVariables.GTK_USE_PORTAL = "1";` NixOS option
directly to set the environment variable globally.
