Merge ~barryprice/charm-telegraf:master into charm-telegraf:master

[Barry Price]

Support older Juju 1.x deploys where hookenv.model_name() is undefined

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

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

[Benjamin Allot (ballot)]

LGTM

review: Approve

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

Change successfully merged at revision ac37632f6f4719ba3e58712ec0ec6989665faa55

diff --git a/src/reactive/telegraf.py b/src/reactive/telegraf.py
index e3fcad3..1fbe002 100644
--- a/src/reactive/telegraf.py
+++ b/src/reactive/telegraf.py
@@ -546,7 +546,10 @@ def configure_telegraf():  # noqa: C901
     # add extra juju-related tags to be exposed as labels
     tags.append('juju_application = "{}"'.format(get_remote_unit_name().split("/")[0]))
     tags.append('juju_unit = "{}"'.format(get_remote_unit_name().replace("/", "-")))
-    tags.append('juju_model = "{}"'.format(hookenv.model_name()))
+    try:
+        tags.append('juju_model = "{}"'.format(hookenv.model_name()))
+    except KeyError:
+        pass  # support older Juju 1.x deploys
     context["tags"] = tags
 
     if inputs:
diff --git a/src/tests/unit/test_telegraf.py b/src/tests/unit/test_telegraf.py
index 56da00f..1b97b91 100644
--- a/src/tests/unit/test_telegraf.py
+++ b/src/tests/unit/test_telegraf.py
@@ -843,7 +843,7 @@ outputs:
     assert expected in config_file.read()
 
 
-def test_default_tags(monkeypatch, config):
+def test_default_tags_juju2(monkeypatch, config):
     monkeypatch.setattr(telegraf.hookenv, "principal_unit", lambda: "principal-unit")
     monkeypatch.setattr(telegraf.hookenv, "open_port", lambda p: None)
     telegraf.configure_telegraf()
@@ -863,6 +863,25 @@ def test_default_tags(monkeypatch, config):
     assert expected in config_file.read()
 
 
+def test_default_tags_juju1(monkeypatch, config):
+    monkeypatch.setattr(telegraf.hookenv, "principal_unit", lambda: "principal-unit")
+    monkeypatch.setattr(telegraf.hookenv, "open_port", lambda p: None)
+    monkeypatch.delitem(os.environ, "JUJU_MODEL_NAME")  # no models in Juju 1.x
+    telegraf.configure_telegraf()
+    expected = """
+[tags]
+  # dc = "us-east-1" # will tag all metrics with dc=us-east-1
+  # rack = "1a"
+
+  juju_application = "remote-unit"
+
+  juju_unit = "remote-unit-0"
+
+"""
+    config_file = base_dir().join("telegraf.conf")
+    assert expected in config_file.read()
+
+
 # Plugin tests