Classroom_Desktop/docs/provisioning.md

# Provisioning

Some things a classroom needs cannot be installed by the classroom
package itself: they need the network, and they need the apt lock that
dpkg is holding for the whole of the package's `postinst`.

`ekklesia-classroom-provision.service` runs after every boot and does
them. It is a `oneshot` unit that nothing else waits on, so it never
holds the classroom up, and **it is not allowed to fail the boot**: a
machine with no DVD codecs is still a working classroom.

The package `postinst` enables the service and schedules a delayed start after
the outer apt transaction has had time to release its lock. It never runs
provisioning synchronously inside dpkg. If an OTA reboot happens before the
delayed job, the enabled service runs normally on the next boot.

To provision without waiting for a reboot:

```
sudo classroom-provision
```

Each step checks whether it is already done and returns immediately if
so. A provisioned machine costs nothing; a machine that was offline the
first time gets another go at the next boot.

```
journalctl -u ekklesia-classroom-provision
```

## Google Chrome

Chrome is not in Debian and a classroom is not usable without it, so a
fresh machine installs it itself rather than waiting for someone to do it
by hand on every box.

`classroom-chrome-setup` adds Google's signing key to
`/etc/apt/keyrings/google-chrome.gpg` and their repository to
`/etc/apt/sources.list.d/google-chrome.list` — the same path Google's own
package manages, so the two cannot become two copies of the same
repository — then installs `google-chrome-stable`. Using the repository
rather than a one-off `.deb` means Chrome keeps getting security updates.

Run it by hand with `sudo classroom-chrome-setup`. It returns
immediately if Chrome is already installed.

The Chrome policies in `/etc/opt/chrome/policies/` are shipped by the
classroom package and apply as soon as Chrome exists.

## DVD codecs

Only for rooms with `DVD_ENABLED=true`. See [dvd.md](dvd.md).

## Networking and printing

NetworkManager and CUPS are Debian package dependencies, not deferred network
provisioning steps. Their services are enabled by the package and neither
requires Internet access or hardware to be present.

- Wi-Fi administration: [networking.md](networking.md)
- Church color printer setup: [printing.md](printing.md)

The printer helper is part of every provisioning pass. It is capped at 30
seconds and only configures the local scheduler, so an offline Ricoh cannot
hold boot or provisioning open. Failures are logged and retried on the next
boot. A correctly configured queue is a quick no-op.

## What provisioning does not do

The boot provisioning command never upgrades or reconfigures anything already installed, and it
never touches a repository it did not add. Classroom software updates
are the OTA channel's job, not this.

## When a classroom updates

**Every day at 03:00**, local time, spread over half an hour so the rooms
do not all ask at once: `ekklesia-classroom-update.timer`,
`OnCalendar=*-*-* 03:00:00`, `RandomizedDelaySec=30m`. It has been so
since 0.1.5; the lab's installed stable machine logged its checks at 03:01
on 26 September and 03:04 on 27 September.

**A computer that was switched off at 03:00** checks once, soon after it
is next switched on (`Persistent=true`). Measured on the lab's systemd
with the machine really stopped across the time: the missed check ran 50 s
after it started, once, and not again. Nothing else starts the check —
no boot trigger, no repeat — so it cannot loop.

Each check follows only the device's own `CHANNEL` (a stable room stays
on stable), installs only a newer version, and only a package whose
SHA-256, name and version are what the manifest says.

**The reboot after an update waits for nobody to be using the computer**
(since 0.2.6.5). It used to happen the moment the update was installed:
harmless at 03:00, and a room restarting itself mid-morning after a night
switched off. Now `classroom-reboot-when-idle` reboots once no keyboard,
mouse, touchpad or touchscreen has been touched for 30 minutes *and* no
sound has played for as long — a video to the room is not an idle
computer. At 03:00 that is about 03:30. Switched off before then, nothing
is lost: the update is installed and the next start is on it. Until the
reboot the session carries on as it was; the only other thing an update
starts at once, provisioning, does nothing on a machine that is already
set up.

Input is read from the kernel's input devices, whatever the desktop is
doing; sound from the kernel's own playback state (`/proc/asound`). Both
measured in the lab — a mouse made with `/dev/uinput` kept it from
rebooting, and leaving it alone let it — except the sound card, which the
lab does not have: that is a check on real hardware.

The schedule is a file the package installs, not a configuration file,
so every upgrade brings the packaged schedule. The release gate checks it
after a fresh install and after each upgrade.

    systemctl list-timers ekklesia-classroom-update.timer   # next and last check
    journalctl -u ekklesia-classroom-update                 # what each check did
    journalctl -u ekklesia-classroom-reboot-when-idle       # a reboot that is waiting

## Permanent download addresses

```
https://updates.riverofglorymn.org/stable/latest.deb
https://updates.riverofglorymn.org/canary/latest.deb
```

One address per channel that never changes. Each is a symlink beside that
channel's manifest, pointing at the versioned package the manifest names,
so there is still exactly one record of which version is current — the
manifest. Nothing here is a second version database.

The versioned files under `/packages/` are never rewritten. A release
uploads its package, then the manifest, then swaps the pointer by rename.
Renaming is atomic, so nothing downloads a half-written pointer, and
going last means `latest.deb` can lag the manifest by a moment but can
never lead it: it will never offer a package the channel has not
published.

`latest.deb` and `manifest.json` are served `no-store, no-cache,
must-revalidate`. That header matters more than it looks: Cloudflare sits
in front of this server and caches `.deb` by extension, so without it a
room could be handed the previous release from an edge for hours. The
versioned packages are deliberately left cacheable — they are immutable.

**Installing from a channel URL does not move a machine onto that
channel.** `CHANNEL` in device.conf is the only thing that decides which
manifest the updater follows, and the package's postinst only ever
appends settings that are missing. Downloading the canary package to fix
a machine by hand leaves it on stable, and the next automatic update
brings it back to stable.

Verify a download against the channel it came from:

```
curl -fsSL -o c.deb https://updates.riverofglorymn.org/canary/latest.deb
sha256sum c.deb
curl -fsS https://updates.riverofglorymn.org/canary/manifest.json
```

## Version numbers and releasing

```
0.2.6     a feature release
0.2.6.1   the first maintenance release of 0.2.6
0.2.6.2   the second
0.2.7     the next feature release
0.3.0     a larger milestone
```

Three parts for a feature release, four for a maintenance release of one.
The leading zero stays until Classroom is feature-complete; 1.0.0 belongs
to the wider Ekklesia platform's milestone. Nothing else is a version: no
leading zeros (dpkg reads `0.2.06` as `0.2.6`), no `0.2.6.0`, no suffixes.
The build, both publish scripts and every classroom's updater refuse
anything else, from one pattern held to one list of cases by
`tests/test-release-versions.sh`.

Which of two versions is newer is always `dpkg --compare-versions`, never
our own arithmetic, because dpkg is what installs them:
`0.2.2 < 0.2.6 < 0.2.6.1 < 0.2.6.2 < 0.2.6.10 < 0.2.7`.

### A published version is never used again

0.2.6 was rebuilt with later fixes and uploaded a second time under the
same number, replacing the first upload. A room that had installed the
first one could never be offered the second: the updater only installs a
version newer than its own. So now:

* `update_canary.sh VERSION` refuses a version that has ever been
  published — on the server or in `repo/packages` — and one that is not
  newer than every package ever published. It checks before building and
  again after the Trixie gate.
* Packages are uploaded with `rsync --ignore-existing`, and the checksum on
  the server is compared with the one built before anything points at it.
* A manifest is only written once the server holds exactly the package
  and checksum it names.
* After publishing, the channel is read back over HTTPS the way a classroom
  reads it: manifest, versioned package, `latest.deb` and the version dpkg
  reads out of the file must all agree.

A publish that fails after the local copy into `repo/packages` has spent
that number. Use the next one.

### Canary (Preview)

Since 0.2.6.6 releases normally go through Gitea: built once, recorded as
a Gitea release, published and promoted by workflows that call these same
scripts. [releasing.md](releasing.md) has the whole path. By hand:

```
./update_canary.sh 0.2.6.7 dist/ekklesia-classroom_0.2.6.7_amd64.deb   # gate and publish THAT file
./update_canary.sh 0.2.7                                               # build, gate and publish
```

The version is always given. With four parts there are two possible next
numbers, and which one a release is depends on what is in it. Run with no
argument it prints the current canary and both candidates, and builds
nothing.

Given a package, that file is what is gated and published; nothing is
rebuilt, because a second build is a second, untested file. The gate is
`tools/release-gate.sh`: a fresh install, and the upgrade from whatever
canary and stable serve, each on a room of that channel;
`RELEASE_GATE_FROM=0.2.2` adds an older release rooms are still on.

### Stable

```
./update_stable.sh 0.2.6.6 <sha256>
```

Only with the owner's written approval for that release. Stable is never
given a package of its own: it is pointed at one canary already published,
byte for byte, and refuses a version that is not newer than stable's
current one or whose package the server does not hold with the same
checksum. With the sha256 — always give it — it refuses any file but the
one that was approved.

### Checking a channel without changing it

```
ROOT=$PWD bash -c 'source tools/release-lib.sh; release_verify_channel stable; release_verify_channel canary'
```

### Rehearsing an upgrade

`tools/validate-trixie-release.sh NEW.deb [PREVIOUS.deb]` installs into a
clean Debian 13 container. `VALIDATION_CHANNEL=stable` rehearses a stable
room, for example the desktops' real path:

```
VALIDATION_CHANNEL=stable tools/validate-trixie-release.sh \
    dist/ekklesia-classroom_0.2.6.1_amd64.deb \
    repo/packages/ekklesia-classroom_0.2.2_amd64.deb
```