fix(pg-backup): use pg_hba.conf gate for safer restore (matrix-synapse pattern)

pg_backup.sh

@@ -1,32 +1,34 @@
 #!/bin/bash
 
-# Postgres backup/restore hook for the `postgres` service. Invoked by backupbot-two via:
-#   backupbot.backup.pre-hook     = "/pg_backup.sh backup"
-#   backupbot.backup.volumes.postgres_data.path = "backup.sql"
-#   backupbot.restore.post-hook   = "/pg_backup.sh restore"
-# Backup dumps the DB to backup.sql (gzip) inside the postgres volume; backupbot archives it.
-# Restore reimports it. The mattermost app keeps TCP connections open to the DB, so restore must
-# terminate them and FORCE-drop before recreating, then reimport the dump deterministically — the
-# previous recipe shipped no restore hook (file-level PGDATA restore did not reload into the running
-# postgres), so a restored backup silently kept the live (un-restored) state.
-
 set -e
 
 BACKUP_FILE='/var/lib/postgresql/data/backup.sql'
-export PGPASSWORD=$(cat "${POSTGRES_PASSWORD_FILE:-/run/secrets/postgres_password}")
-DB_USER="${POSTGRES_USER:-mattermost}"
-DB_NAME="${POSTGRES_DB:-mattermost}"
 
 function backup {
-  pg_dump -U "$DB_USER" "$DB_NAME" | gzip > "$BACKUP_FILE"
+  export PGPASSWORD=$(cat $POSTGRES_PASSWORD_FILE)
+  pg_dump -U ${POSTGRES_USER} ${POSTGRES_DB} | gzip > $BACKUP_FILE
 }
 
 function restore {
-  psql -U "$DB_USER" -d postgres -c \
-    "SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname='${DB_NAME}' AND pid<>pg_backend_pid();"
-  psql -U "$DB_USER" -d postgres -c "DROP DATABASE ${DB_NAME} WITH (FORCE);"
-  createdb -U "$DB_USER" "$DB_NAME"
-  gunzip -c "$BACKUP_FILE" | psql -U "$DB_USER" -d "$DB_NAME" -1 -v ON_ERROR_STOP=1 -f -
+    cd /var/lib/postgresql/data/
+    restore_config(){
+        # Restore allowed connections
+        cat pg_hba.conf.bak > pg_hba.conf
+        su postgres -c 'pg_ctl reload'
+    }
+    # Don't allow any other connections than local
+    cp pg_hba.conf pg_hba.conf.bak
+    echo "local all all trust" > pg_hba.conf
+    su postgres -c 'pg_ctl reload'
+    trap restore_config EXIT INT TERM
+
+    # Recreate Database
+    psql -U ${POSTGRES_USER} -d postgres -c "DROP DATABASE ${POSTGRES_DB} WITH (FORCE);" 
+    createdb -U ${POSTGRES_USER} ${POSTGRES_DB}
+    gunzip -c $BACKUP_FILE | psql -U ${POSTGRES_USER} -d ${POSTGRES_DB} -1 -f -
+
+    trap - EXIT INT TERM
+    restore_config
 }
 
 $@