Setup room cleaning automation

machines/pendulum/automation.nix

@@ -0,0 +1,36 @@
+{ config, lib, pkgs, ... }:
+let
+  path = with pkgs; [ jq postgresql_15 matrix-synapse-tools.synadm ];
+  environment = {
+    HOME = "/home/nathan";
+    XDG_CONFIG_DIRS =
+      "/etc/xdg:/home/nathan/.nix-profile/etc/xdg:/etc/profiles/per-user/nathan/etc/xdg:/nix/var/nix/profiles/default/etc/xdg:/run/current-system/sw/etc/xdg";
+    XDG_CONFIG_HOME = "/home/nathan/.config";
+  };
+  synapse-script = { name, script, schedule }: {
+    systemd.services."synapse-script-${name}" = {
+      inherit environment;
+      inherit path;
+      inherit script;
+      serviceConfig = {
+        Type = "oneshot";
+        User = "nathan";
+        Group = "users";
+      };
+    };
+    systemd.timers."synapse-script-${name}" = {
+      wantedBy = [ "timers.target" ];
+      partOf = [ "synapse-script-${name}.service" ];
+      timerConfig = {
+        OnCalendar = schedule;
+        Unit = "synapse-script-${name}.service";
+      };
+    };
+  };
+in lib.mkMerge [
+  (synapse-script {
+    name = "clean-vacant-rooms";
+    schedule = "23:00";
+    script = builtins.readFile ../../scripts/matrix/clean-old-rooms.sh;
+  })
+]

machines/pendulum/configuration.nix

@@ -1,7 +1,7 @@
 { config, lib, pkgs, inputs, ... }:
 
 {
-  imports = [ ./matrix.nix ];
+  imports = [ ./matrix.nix ./automation.nix ];
   # Sops setup for this machine
   sops.secrets = {
     "borg-ssh-key" = {

scripts/matrix/clean-old-rooms.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+set -eou pipefail
+
+# Get the list of rooms with no local users
+empty_rooms() {
+    psql -d synapse -c "SELECT room_id FROM room_stats_current WHERE local_users_in_room = 0 \
+        ORDER BY current_state_events DESC LIMIT 1;" -t --csv
+}
+
+# Delete a room and purge its history
+delete_room() {
+    details=$(synadm room details $1)
+    name=$(echo $details | jq -r '.name')
+    canonical_alias=$(echo $details | jq -r '.canonical_aliacanonical_alias')
+    topic=$(echo $details | jq -r '.topic')
+    joined_local_members=$(echo $details | jq -r '.joined_local_members')
+    state_events=$(echo $details | jq -r '.state_events')
+    echo "Deleting room $1 (name: $name, canonical alias: $canonical_alias, topic: $topic)[$joined_local_members]"
+    echo "This will remove $state_events state events"
+    if [[ $joined_local_members == "0" ]];
+    then
+        time synadm --yes room delete $1
+    else
+        echo "Room still had active members!!! $1"
+    fi
+    echo ""
+}
+
+log_file="empty-removal-$(date -Iminutes).log"
+touch $log_file
+for room in $(empty_rooms); do
+    delete_room $room | tee -a $log_file
+done