Validate demotion successor against peer map

plugins/postgresql/plugin.py

@@ -625,6 +625,36 @@ def demote_prepare(config, runtime_state, request_parameters):
             "node": node_name,
         }
 
+    try:
+        peers = parse_replication_peers(
+            config.get("PG_REPLICATION_PEERS", "")
+        )
+    except (TypeError, ValueError):
+        return {
+            "ocf_rc": 1,
+            "ready": False,
+            "reason": "peer_map_invalid",
+            "node": node_name,
+            "successor_node": successor_node,
+        }
+
+    successor_peer = next(
+        (
+            peer for peer in peers
+            if peer["name"].strip().lower() == successor_node
+        ),
+        None,
+    )
+
+    if successor_peer is None:
+        return {
+            "ocf_rc": 1,
+            "ready": False,
+            "reason": "successor_not_configured",
+            "node": node_name,
+            "successor_node": successor_node,
+        }
+
     return {
         "ocf_rc": 0,
         "ready": False,
@@ -634,8 +664,11 @@ def demote_prepare(config, runtime_state, request_parameters):
         "node": node_name,
         "target_node": target_node,
         "successor_node": successor_node,
+        "successor_host": successor_peer["host"],
+        "successor_port": successor_peer["port"],
         "age_seconds": age,
         "checks": {
+            "peer_map": True,
             "notification": True,
             "local_target": True,
             "successor_selected": True,

tests/test-demote-prepare.py

@@ -37,7 +37,13 @@ runtime_state = {
 }
 
 result = plugin.demote_prepare(
-    {"PACEMAKER_NODE_NAME": "david-eve"},
+    {
+        "PACEMAKER_NODE_NAME": "david-eve",
+        "PG_REPLICATION_PEERS": (
+            "david-prodesk=192.168.1.4:5432,"
+            "david-eve=192.168.1.3:5432"
+        ),
+    },
     runtime_state,
     {},
 )
@@ -47,6 +53,9 @@ assert result["ready"] is False
 assert result["identity_validated"] is True
 assert result["reason"] == "database_checks_pending"
 assert result["checks"]["database_checks"] is False
+assert result["checks"]["peer_map"] is True
+assert result["successor_host"] == "192.168.1.4"
+assert result["successor_port"] == 5432
 assert result["mutation"] is False
 assert result["successor_node"] == "david-prodesk"
 print("valid_prepare            accepted")
@@ -90,3 +99,28 @@ print("missing_successor        rejected")
 
 print()
 print("DEMOTE_PREPARE_TEST_PASS=1")
+
+result = plugin.demote_prepare(
+    {
+        "PACEMAKER_NODE_NAME": "david-eve",
+        "PG_REPLICATION_PEERS": (
+            "david-macbookpro=192.168.1.5:5432"
+        ),
+    },
+    {
+        "postgresql": {
+            "notification": {
+                "type": "pre",
+                "operation": "demote",
+                "demote_uname": "david-eve",
+                "promote_uname": "david-prodesk",
+                "received_at": time.time(),
+            },
+        },
+    },
+    {},
+)
+
+assert result["ocf_rc"] == 1
+assert result["reason"] == "successor_not_configured"
+print("unconfigured_successor  rejected")