Prune WAL and old full backups after each successful basebackup

Archive was growing unbounded (~97 GB / 6k segments). Now runs
pg_archivecleanup against the newest .backup marker and deletes
full_* directories beyond FULL_RETENTION=5.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -41,11 +41,26 @@ services:
       - |
         mkdir -p /backup/wal /backup/full
         chown 999:999 /backup/wal
+        FULL_RETENTION=5
         while true; do
           STAMP=$$(date +%Y-%m-%d_%H-%M-%S)
+          DEST="/backup/full/full_$$STAMP"
           echo "Starting full backup: full_$$STAMP"
-          pg_basebackup -h postgres-db -U "$$POSTGRES_USER" -D "/backup/full/full_$$STAMP" -Fp -Xs -P
+          if pg_basebackup -h postgres-db -U "$$POSTGRES_USER" -D "$$DEST" -Fp -Xs -P; then
             echo "Full backup complete: full_$$STAMP"
+            LATEST_BACKUP_MARKER=$$(ls /backup/wal/*.backup 2>/dev/null | sort | tail -n1)
+            if [ -n "$$LATEST_BACKUP_MARKER" ]; then
+              echo "Cleaning WAL older than $$(basename "$$LATEST_BACKUP_MARKER")"
+              pg_archivecleanup /backup/wal "$$(basename "$$LATEST_BACKUP_MARKER")"
+            fi
+            ls -1dt /backup/full/full_* | tail -n +$$((FULL_RETENTION + 1)) | while read -r old; do
+              echo "Removing old full backup: $$old"
+              rm -rf "$$old"
+            done
+          else
+            echo "Full backup FAILED for full_$$STAMP - skipping cleanup"
+            rm -rf "$$DEST"
+          fi
           sleep 604800
         done