Elastic security, our own metrics, and an alert pipeline that can actually reach Discord

Observability was running but could not report anything. This closes that end to end and
makes every piece of it reproducible from the installers instead of from a shell history.

Logs
- Filebeat 9 REMOVED the container input; it refuses the config per container and then runs
  with zero harvesters and no index. Container logs now use filestream + the container parser
  with a stable id each, and add_docker_metadata is told where the id is.
- Every line gets event.dataset, or Kibana's Logs rate chart is one "unknown" bucket.
- Beats pin replicas to 0: a single node cannot place one, so the cluster sat yellow forever.

Security
- xpack.security.enabled=true, because Kibana's Observability apps ask Elasticsearch whether
  the user holds a privilege and that API does not exist when security is off (the
  Infrastructure page failed on every view). Nobody sees a login: Kibana's anonymous provider
  signs every visitor in as one native user, and Caddy + Authentik + DIAG_REQUIRE_GROUP stays
  the only gate. configure.py generates the service passwords, creates the accounts and writes
  a root-only netrc for the deadman; --es-security retries just that step.

Alerting
- A basic licence has no webhook connector (403, Gold+), so Kibana's rules write documents into
  a vanguard-alerts index through the free .index connector and vanguard-alerts.timer delivers
  them to Discord. Alerts are therefore searchable beside the logs that caused them.
- Six rules in observability/kibana-alarms.py: disk and memory below 15% free, bot not running,
  bot unhealthy, recordings stuck over an hour, normalise failures parked. Each repeats every
  12 h while unresolved.
- The deadman watches both halves of that pipeline, since nothing inside the stack can report
  that the stack's own alerting died.

Our own metrics
- bin/vgmetrics.sh counters from the sweep and vgdeband, plus live gauges on dumpd /metrics
  (loopback only, unrouted by Caddy), scraped by Metricbeat. vanguard_media_pending is the
  measured answer to whether normalising keeps up, which was previously only a benchmark guess.
- The sweep now captures ffmpeg's stderr: rc= alone was not diagnosable.
- Its file loop reads a process substitution, not a pipe, or the subshell discards every counter.

Housekeeping
- configure.py --apply installs the media scripts (it never did, so applies left stale binaries),
  creates the alert index, injects an ILM delete phase and runs Kibana's first-run setup.
- The discord-bot container asks the bot about itself via /health rather than probing a port.
- Removed the dead diag landing page: Kibana occupies the root of that host.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

install.sh

@@ -38,6 +38,7 @@ echo "== media user + folders"
 getent passwd 1000 >/dev/null || useradd -r -u 1000 -d /srv/media -s /usr/sbin/nologin media
 usermod -aG docker "$OWNER" 2>/dev/null || true
 install -d -o 1000 -g 1000 /srv/media/{streams,clips,finals,trash,.markers,.syncthing}
+install -d -o 1000 -g 1000 /srv/media/.markers/metrics                             # script counters -> dumpd /metrics
 install -d -o 1000 -g 1000 /srv/appdata/jellyfin/{config,cache} /srv/appdata/authentik/{media,templates,certs}
 install -d /srv/appdata/authentik/{db,redis} /srv/appdata/mariadb
 install -d -o 1000 -g 1000 /srv/appdata/discord-bot /srv/appdata/gitea /srv/appdata/act_runner
@@ -56,19 +57,21 @@ done
 
 echo "== host scripts + units"
 install -m 0755 bin/normalize-sweep.sh bin/trash-purge.sh bin/dumpd.py bin/vgstrip.py bin/vgdeband.sh /usr/local/bin/
+install -m 0644 bin/vgmetrics.sh /usr/local/bin/      # sourced by the sweep/vgdeband; counters for dumpd's /metrics
 install -m 0755 deployBotBundle.sh /usr/local/bin/vanguard-deploy-bot   # dumpd runs this for the bot CI's POST /deploy-bot
 install -m 0755 bin/vanguard-deadman.sh /usr/local/bin/      # watches the observability stack from outside it
-# Compose bind-mounts this as a FILE; without it Docker would create a directory and alertmanager would not
-# start. configure.py rewrites it from ALERT_WEBHOOK_URL on every apply; an empty one means "log only".
+install -m 0755 bin/vanguard-alerts.sh /usr/local/bin/        # takes Kibana's alert documents to Discord
+# Read by the root timers vanguard-alerts.sh (delivery) and vanguard-deadman.sh. configure.py rewrites it
+# from ALERT_WEBHOOK_URL on every apply; an empty one means "journal only, and exit non-zero".
 if [[ ! -f /etc/vanguard/alert-webhook ]]; then
   install -d -m 0750 /etc/vanguard
-  install -m 0640 -o root -g 65534 /dev/null /etc/vanguard/alert-webhook
+  install -m 0600 -o root -g root /dev/null /etc/vanguard/alert-webhook   # root timers are the only readers
 fi
 install -d -m 0750 /etc/vanguard
 install -m 0640 dump-users.txt /etc/vanguard/dump-users.txt
 install -m 0644 systemd/*.service systemd/*.timer /etc/systemd/system/
 systemctl daemon-reload
-systemctl enable --now normalize-sweep.timer trash-purge.timer dumpd.service vanguard-deadman.timer
+systemctl enable --now normalize-sweep.timer trash-purge.timer dumpd.service vanguard-deadman.timer vanguard-alerts.timer
 
 echo "== sysctl"
 cat > /etc/sysctl.d/90-vanguard.conf <<'SYS'