PBCKP-2912: add sanity check in set_archiving(instance should exists)

Author: Stepan Neretin

pg_probackup2/app.py

@@ -778,6 +778,13 @@ def set_archiving(
             log_level=False, archive_timeout=False,
             custom_archive_command=None):
 
+        # check instance existing
+        instances_json = self.show(instance=None, as_json=True, expect_error=False, as_text=True)
+        instances_data = json.loads(instances_json)
+        if not any(inst_data.get('instance') == instance for inst_data in instances_data):
+            assert False, "Instance '{0}' does not exist. " \
+                          "Please add the instance first using add_instance() or init_pb_node().".format(instance)
+
         # parse postgresql.auto.conf
         options = {}
         if replica:

pg_probackup2/tests/test_basic.py

@@ -5,9 +5,9 @@
 import pytest
 
 import testgres
-from ...pg_probackup2.app import ProbackupApp
-from ...pg_probackup2.init_helpers import Init, init_params
-from ..storage.fs_backup import FSTestBackupDir
+from pg_probackup2.app import ProbackupApp
+from pg_probackup2.init_helpers import Init, init_params
+from pg_probackup2.storage.fs_backup import FSTestBackupDir
 
 
 class ProbackupTest:
@@ -102,3 +102,22 @@ def test_full_backup(self):
 
             # Check if the backup is valid
             assert f"INFO: Backup {backup_id} is valid" in out
+
+    def test_set_archiving_nonexistent_instance(self):
+        self.pb.init()
+
+        with pytest.raises(AssertionError) as exc_info:
+            self.pb.set_archiving('nonexistent_instance', None)
+
+        assert "Instance 'nonexistent_instance' does not exist" in str(exc_info.value)
+
+    def test_set_archiving_existing_instance(self):
+        node = self.pg_node.make_simple('node', pg_options={"fsync": "off", "synchronous_commit": "off"})
+
+        with node:
+            self.pb.init()
+            node.slow_start()
+            self.pb.add_instance('node', node)
+            self.pb.set_archiving('node', node)
+
+            assert "does not exist" not in str(self.pb.test_class.output or "")