From d85583339f91a74d6d9f36b57e2c1e5df2991278 Mon Sep 17 00:00:00 2001
From: Adam Dyess <adam.dyess@canonical.com>
Date: Sun, 10 Mar 2024 12:21:59 -0500
Subject: [PATCH] search for node in calico-early config by stableAddress (#4)

---
 src/peer.py             | 28 ++++++++++++++++++++++++++--
 tests/unit/test_peer.py | 14 +++++++++++++-
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/src/peer.py b/src/peer.py
index 86fb77d..3e7857b 100644
--- a/src/peer.py
+++ b/src/peer.py
@@ -4,6 +4,7 @@
 import socket
 from ipaddress import ip_address
 from pathlib import Path
+from subprocess import CalledProcessError, check_output
 from typing import List, Mapping, Optional, Set
 
 import yaml
@@ -24,6 +25,20 @@ def _read_file_content(path: Path) -> Optional[str]:
     return path.read_text() if path.exists() else None
 
 
+def _localhost_ips() -> List[ip_address]:
+    try:
+        lo_ifc = yaml.safe_load(check_output(["ip", "--json", "addr", "show", "lo"]))
+    except (CalledProcessError, yaml.YAMLError):
+        log.exception("Couldn't fetch the ip addresses of lo")
+        return []
+    return [
+        ip_address(addr["local"])
+        for ifc in lo_ifc
+        if ifc["ifname"] == "lo"
+        for addr in ifc["addr_info"]
+    ]
+
+
 class BGPPeer(BaseModel):
     """Represents a host interface's bpg peer info."""
 
@@ -101,10 +116,19 @@ def _early_service_cfg() -> Optional[BGPParameters]:
         log.warning(f"Couldn't find calico early config in {yaml_location}")
         return None
 
+    stable_address = None
+    for ip in _localhost_ips():
+        if not ip.is_loopback:
+            stable_address = ip
+
     early_cfg = yaml.safe_load(content)
     try:
-        node = early_cfg["spec"]["nodes"][0]
-    except (TypeError, KeyError, IndexError):
+        for node in early_cfg["spec"]["nodes"]:
+            if node["stableAddress"]["address"] == str(stable_address):
+                break
+        else:
+            raise KeyError(f"No node matches {stable_address}")
+    except (TypeError, KeyError):
         log.warning(f"Config File didn't contain spec.nodes in config={yaml_location}")
         return None
     hostname = socket.gethostname()
diff --git a/tests/unit/test_peer.py b/tests/unit/test_peer.py
index 6fa7eba..21f4adf 100644
--- a/tests/unit/test_peer.py
+++ b/tests/unit/test_peer.py
@@ -4,6 +4,7 @@
 # Learn more about testing at: https://juju.is/docs/sdk/testing
 
 import unittest.mock as mock
+from ipaddress import ip_address
 from textwrap import indent
 
 import ops.testing
@@ -46,6 +47,17 @@ def early_service():
         yield patched
 
 
+@pytest.fixture
+def localhost_ips():
+    with mock.patch("peer._localhost_ips") as patched:
+        patched.return_value = [
+            ip_address("127.0.0.1"),
+            ip_address("10.10.10.1"),
+            ip_address("::1"),
+        ]
+        yield patched
+
+
 LOCAL_BGP_PARAMS = """
 asNumber: 20001
 interfaceAddresses:
@@ -79,7 +91,7 @@ def early_service():
 }"""
 
 
-def test_peer_relation_data(harness, charm, early_service):
+def test_peer_relation_data(harness, charm, early_service, localhost_ips):
     rel_id = 0  # peer-relation is always 0
     harness.add_relation_unit(rel_id, "calico-enterprise/0")
     harness.set_leader(True)