Merge ~aluria/charm-telegraf:lp1775062 into ~telegraf-charmers/charm-telegraf:master

[Alvaro Uria]

LP#1775062 Fix regression at 2920829

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Thomas Cuthbert (tcuthbert)]

This needed the netifaces package added to the test requirements, other than that +1

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision 8d4b1413be4756028e5db77e44e48e7bfb373577

diff --git a/layer.yaml b/layer.yaml
index c8b5db2..678d4eb 100644
--- a/layer.yaml
+++ b/layer.yaml
@@ -34,6 +34,7 @@ options:
         include_system_packages: true
         packages:
             - python3-yaml
+            - python3-netifaces
     apt:
         packages:
             - telegraf
diff --git a/reactive/telegraf.py b/reactive/telegraf.py
index 94de186..174c64e 100644
--- a/reactive/telegraf.py
+++ b/reactive/telegraf.py
@@ -23,6 +23,7 @@ import socket
 import time
 import yaml
 import re
+import netifaces
 
 from charms.reactive import (
     helpers,
@@ -108,11 +109,27 @@ def get_hostname_label():
 
 
 def get_remote_unit_name():
-    for rel_type in hookenv.metadata()['requires'].keys():
-        rels = hookenv.relations_of_type(rel_type)
-        if rels and len(rels) >= 1:
-            rel = rels[0]
-            return rel['__unit__']
+    unit = os.environ.get('JUJU_PRINCIPAL_UNIT', None)
+    if unit:
+        # Note(aluria): use Juju env var available since 2017
+        return unit
+    else:
+        # Note(aluria): lookup all available IPv4/IPv6 addresses (except lo)
+        ip_addresses = set()
+        for iface in netifaces.interfaces():
+            if iface == 'lo':
+                continue
+            ip_addrs = netifaces.ifaddresses(iface)
+            for iface_type in ip_addrs:
+                if iface_type in (netifaces.AF_INET, netifaces.AF_INET6):
+                    for addrs in ip_addrs[iface_type]:
+                        ip_addresses.add(addrs['addr'])
+
+        # Note(aluria): and try to match them against rel['private-address']
+        for rel_type in hookenv.metadata()['requires'].keys():
+            for rel in hookenv.relations_of_type(rel_type):
+                if rel['private-address'] in ip_addresses:
+                    return rel['__unit__']
 
 
 def render_base_inputs():
diff --git a/test_requirements.txt b/test_requirements.txt
index 676f7c1..64be687 100644
--- a/test_requirements.txt
+++ b/test_requirements.txt
@@ -9,5 +9,6 @@ charms.reactive
 amulet
 requests
 juju-wait
+netifaces
 #--find-links https://launchpad.net/python-apt/+download/
 #python-apt
diff --git a/unit_tests/test_telegraf.py b/unit_tests/test_telegraf.py
index b83d972..3071b10 100644
--- a/unit_tests/test_telegraf.py
+++ b/unit_tests/test_telegraf.py
@@ -129,19 +129,64 @@ def persist_state():
 
 
 # Tests
-def test_get_remote_unit_name(monkeypatch):
+def test_get_remote_unit_name_juju2(monkeypatch):
     monkeypatch.undo()
-    # fix hookenv.metadata
-    real_charm_dir = os.path.join(os.path.dirname(reactive.__file__), "../")
-    with open(os.path.join(real_charm_dir, 'metadata.yaml')) as md:
-        metadata = yaml.safe_load(md)
-    monkeypatch.setattr(telegraf.hookenv, 'metadata', lambda: metadata)
+    monkeypatch.setitem(os.environ, 'JUJU_PRINCIPAL_UNIT', 'remote/0')
+    assert telegraf.get_remote_unit_name() == 'remote/0'
+
+
+def test_get_remote_unit_name_juju1(monkeypatch):
+    monkeypatch.undo()
+    monkeypatch.setattr(telegraf.netifaces,
+                        'interfaces',
+                        lambda: ['lo', 'eth0'])
+
+    ifaddresses = {17: [{'addr': 'AA:BB:CC:DD:EE:FF',
+                         'broadcast': 'ff:ff:ff:ff:ff:ff'}],
+                   2: [{'addr': '1.2.3.4',
+                        'netmask': '255.255.255.0',
+                        'broadcast': '1.2.3.1'}],
+                   10: [{'addr': '2620:0:862:ed1a::1',
+                         'netmask': 'ffff:ffff:ffff:ffff::'}]}
+    monkeypatch.setattr(telegraf.netifaces,
+                        'ifaddresses',
+                        lambda n: ifaddresses if n == 'eth0' else {})
+
+    md = {'name': 'telegraf',
+          'requires': {'mysql': {'interface': 'mysql-root'},
+                       'postgresql': {'interface': 'pgsql'},
+                       'mongodb': {'interface': 'mongodb',
+                                   'scope': 'container'},
+                       'memcached': {'interface': 'memcache',
+                                     'scope': 'container'},
+                       'elasticsearch': {'interface':
+                                         'elasticsearch',
+                                         'scope': 'container'},
+                       'haproxy': {'interface': 'statistics',
+                                   'scope': 'container'},
+                       'apache': {'interface': 'apache-website',
+                                  'scope': 'container'},
+                       'influxdb-api': {'interface':
+                                        'influxdb-api'},
+                       'juju-info': {'interface': 'juju-info',
+                                     'scope': 'container'},
+                       'exec': {'interface': 'telegraf-exec',
+                                'scope': 'container'}},
+          'provides': {'prometheus-client': {'interface': 'http'},
+                       'prometheus-rules': {'interface': 'prometheus-rules'}}}
+    monkeypatch.setattr(telegraf.hookenv, 'metadata', lambda: md)
+
     relations = []
-    monkeypatch.setattr(telegraf.hookenv, 'relations_of_type', lambda n: relations)
-    monkeypatch.setattr(telegraf.hookenv, 'unit_private_ip', lambda: '1.2.3.4')
+    monkeypatch.setattr(telegraf.hookenv,
+                        'relations_of_type',
+                        lambda n: relations)
     assert telegraf.get_remote_unit_name() is None
-    relations = [{'private-address': '1.2.3.4', '__unit__': 'remote-0'}]
-    assert telegraf.get_remote_unit_name() == 'remote-0'
+
+    relations = [{'private-address': '1.2.3.4', '__unit__': 'remote/0'}]
+    monkeypatch.setattr(telegraf.hookenv,
+                        'relations_of_type',
+                        lambda n: relations)
+    assert telegraf.get_remote_unit_name() == 'remote/0'
 
 
 def test_inputs_config_set(monkeypatch, config):