doc: update docs

Author: Deezzir

docs/explanation/architecture.md

@@ -33,12 +33,13 @@ Service                                          Startup   Current  Notes
 charmed-postgresql.patroni                       enabled   active   -
 charmed-postgresql.pgbackrest-service            enabled   active   -
 charmed-postgresql.prometheus-postgres-exporter  enabled   active   -
+charmed-postgresql.pgbackrest-exporter           enabled   active   -
 
 ```
 
 The `patroni` snap service is a main PostgreSQL instance which is normally up and running right after the charm deployment.
 
-The `pgbackrest` snap service is a backup framework for PostgreSQL. It is disabled if [Backup](/how-to/back-up-and-restore/create-a-backup) is not configured.
+The `pgbackrest` snap servics is a backup framework for PostgreSQL. It is disabled if [Backup](/how-to/back-up-and-restore/create-a-backup) is not configured along with the `pgbackrest-exporter` service.
 
 The `prometheus-postgres-exporter` service is activated after the relation with [COS Monitoring](/how-to/monitoring-cos/enable-monitoring) only.
 

docs/reference/alert-rules.md

@@ -48,8 +48,17 @@ This page contains a markdown version of the alert rules described in the `postg
 | PatroniPostgresqlDown | ![critical] | Patroni PostgreSQL instance is down.<br>Check for errors in the Loki logs. |
 | PatroniHasNoLeader | ![critical] | Patroni instance has no leader node.<br>A leader node (neither primary nor standby) cannot be found inside a cluster.<br>Check for errors in the Loki logs. |
 
+## `PgbackrestExporterK8s`
+
+| Alert | Severity | Notes |
+| ----- | -------- | ----- |
+| `PgBackRestBackupError` | ![critical] | Backup failed for a stanza.<br>The last pgBackRest backup ended with error status > 0.<br>Check the pgBackRest logs for the stanza. |
+| `PgBackRestBackupTooOld` | ![warning] | No recent backup available.<br>The last pgBackRest backup is older than 7 days.<br>Consider checking your backup schedule, capacity, and logs. |
+| `PgBackRestStanzaError` | ![warning] | A stanza has reported errors.<br>Status > 0 indicates problems such as missing stanza path or no valid backups.<br>Check pgBackRest logs for details. |
+| `PgBackRestRepoError` | ![warning] | A repository has reported errors.<br>Status > 0 indicates the repo may be inaccessible, out of space, or otherwise unhealthy.<br>Check pgBackRest logs and storage system. |
+| `PgBackRestExporterError` | ![critical] | The pgBackRest exporter failed to fetch data.<br>Metric `pgbackrest_exporter_status == 0` indicates exporter-side issues.<br>This may be a misconfiguration or runtime error; check exporter logs. |
+
 <!-- Badges -->
 [info]: https://img.shields.io/badge/info-blue
 [warning]: https://img.shields.io/badge/warning-yellow
 [critical]: https://img.shields.io/badge/critical-red
-

docs/reference/troubleshooting/index.md

@@ -83,6 +83,7 @@ Service                                          Startup   Current   Notes
 charmed-postgresql.patroni                       enabled   active    -
 charmed-postgresql.pgbackrest-service            enabled   active    -
 charmed-postgresql.prometheus-postgres-exporter  enabled   active    -
+charmed-postgresql.pgbackrest-exporter           enabled   active   -
 
 ubuntu@juju-fd7874-0:~$ systemctl --failed
 ...