jochen
c790ee24d3
The host refuses boot on a service that leaves its state to the machine, so lemurs.service is declared running (no trigger, so a push still never restarts it). pacman-contrib is the pacman module's, and two modules declaring one package make a node unresolvable.
103 lines
6.0 KiB
Markdown
103 lines
6.0 KiB
Markdown
# lemurs
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The login manager as a module (novox/hq ADR 0208, research 026, to-be 42 phase 2, step 3).
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- **Claims `node-login-manager`** and serves its verb `sessions`.
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- **Package `lemurs`**, from the official repositories. It replaces the user repository's
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`lemurs-git` that both workstations run.
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- **Service `lemurs.service`, enabled at boot and running.** It is its own `display-manager.service`
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alias. It declares no restart or reload trigger, so a push starts it only where it is not running
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and never restarts it, because restarting it ends the session it started. (A state is required:
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the host refuses `boot` on a service that leaves its state to the machine.) A change to its configuration applies at its next
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start (a reboot).
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- **Gated by `package-manager`, `service-manager` and `seat`.** A machine without a display has
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nothing to log into.
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## What it owns
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| path | class | what |
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| `/etc/lemurs/config.toml` | owned (the found file is kept once, ADR 0102) | lemurs 0.4's configuration in its current format: the structure of the shipped file, every option present, as lemurs requires. The source is [`config/config.toml`](config/config.toml), carried whole in the manifest |
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| `/etc/lemurs/xsessions/`, `/etc/lemurs/wayland-sessions/` | owned, empty | where the configuration points lemurs for desktop entries, so none is offered |
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**Sessions are drop-ins.** The sessions offered are the executable files session modules place in
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`/etc/lemurs/wms/` (X) and `/etc/lemurs/wayland/` (Wayland). The file's name is the session's name.
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`i3` places `/etc/lemurs/wms/i3`, and `sway` will place its own in `wayland/`. The desktop entries
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packages install (`/usr/share/xsessions/i3.desktop`, `i3-with-shmlog.desktop`) are no longer offered.
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They start the window manager bare, skipping `~/.xinitrc`, which holds the environment, the
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resources and every module's session lines. Today the workstations log in through exactly such an
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entry (`i3`). It reaches the session's start only because `~/.xprofile` sources `~/.xinitrc`.
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**What the configuration changes** from the shipped file, each marked `mesh:` in it:
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- the two desktop-entry directories, as above;
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- `switcher_visibility = "F3"`. The session switcher stays hidden as today, and F3 shows it once a
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second session (sway) exists.
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Everything else is lemurs's default, which is also what runs today: X on `:1`, tty 2, the cache in
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`/var/cache/lemurs`, `remember = true`. The workstations' current file is two releases old. The
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running `lemurs-git` ignores its X keys and uses these defaults already, which is why X is on `:1`
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although the file says `:0`.
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## Tools
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| tool | | what |
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| `node-login-manager.sessions` | r | each session offered: name, X11 or Wayland, script or desktop entry, the file and what it runs, whether lemurs can run it (a script that is not executable is skipped); the default session and account from the cache |
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| `lemurs_default_session` | r/a | the preselected session; set it to one that is offered. It writes the cache through `sudo -n`, and shows when lemurs next starts |
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| `lemurs_logins` | r | logins from the journal (opened, closed, failed passwords), and which entry lemurs started each session with (its own log) |
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None needs the graphical session.
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## What it improves
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- the official package instead of a `-git` build from the user repository;
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- the configuration in the format the binary reads. Today's file is mostly ignored, and the unmerged
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`.pacnew` sits beside it;
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- one session per session module, each starting through the session's start, and no bare desktop
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entries;
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- a dead entry gone: `/etc/lemurs/wms/i3wm` (`exec startx`) would start a second X server inside
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the one lemurs started.
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## What it leaves found
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- `/etc/lemurs/xsetup.sh`, the package's;
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- `/etc/pam.d/lemurs`, the package's (it unlocks the login keyring through `pam_gnome_keyring`);
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- `/var/cache/lemurs`, lemurs's own.
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## The one-off migration (ADR 0182)
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1. **Replace the package by hand, once per workstation, at a moment you choose:**
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`sudo pacman -S lemurs`, answering yes to removing `lemurs-git` (and `lemurs-git-debug` on the
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laptop). The host cannot do this. `pacman -Q lemurs` answers with `lemurs-git`, which provides
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`lemurs`, so the declared package already reads as installed. A non-interactive install would
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also refuse the conflict. The binary is replaced on disk, and the running login manager keeps
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running the old one until the next boot.
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2. **Delete `/etc/lemurs/config.toml.pacnew`.** The module's file is that structure.
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3. **Delete `/etc/lemurs/wms/i3wm`** once `i3` is assigned and `/etc/lemurs/wms/i3` exists.
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4. **Delete `~/.xprofile`**, or its `. ~/.xinitrc` line (see `xorg`'s README). Until then the X setup
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runs `~/.xinitrc` from `.xprofile` before it reaches the session's entry. That still works, once.
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Steps 1, 2 and 3 are harmless in any order. Step 4 waits for `i3`.
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## What changes when it is assigned
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| | g14 | shanks |
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|---|---|---|
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| package | nothing until step 1 (`lemurs-git` reads as installed) | the same |
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| `/etc/lemurs/config.toml` | the found file kept once, then the module's written | the same |
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| `/etc/lemurs/xsessions/`, `wayland-sessions/` | created, empty | the same |
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| `lemurs.service` | already enabled: nothing | the same |
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| the running login manager and session | **nothing** | **nothing** |
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| next boot | the login screen offers `i3wm` until step 3, and `i3` once the `i3` module is assigned. It no longer offers the two desktop entries. The remembered session `i3` matches the `i3` module's entry by name | the same |
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**Order matters at one point:** assign `i3` before the next reboot after `lemurs`. Otherwise the
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screen offers only `i3wm`, which runs `startx` inside lemurs's own X server and fails. Assigned in
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to-be 42's order (`xorg`, `lemurs`, `i3` in one sitting), this cannot happen.
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## Blockers
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- **The package swap is a person's act** (step 1). The host's package resource cannot replace a
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package that provides the same name.
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- **No restart, by design.** A configuration change takes a reboot to show.
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