use as_dict() because label_matcher_dict excludes unit (#67)

* use as_dict() because label_matcher_dict excludes unit

* add juju_ prefix again

* rename and extent itest

* remove old itest

* update libs

* increase LIBPATCH

* add link to issue

lib/charms/certificate_transfer_interface/v0/certificate_transfer.py

@@ -109,7 +109,7 @@ def _on_certificate_removed(self, event: CertificateRemovedEvent):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 5
+LIBPATCH = 6
 
 PYDEPS = ["jsonschema"]
 
@@ -379,7 +379,7 @@ def _on_relation_changed(self, event: RelationChangedEvent) -> None:
         )
 
     def _on_relation_broken(self, event: RelationBrokenEvent) -> None:
-        """Handler triggered on relation broken event.
+        """Handle relation broken event.
 
         Args:
             event: Juju event

lib/charms/grafana_agent/v0/cos_agent.py

@@ -234,7 +234,7 @@ class _MetricsEndpointDict(TypedDict):
 
 LIBID = "dc15fa84cef84ce58155fb84f6c6213a"
 LIBAPI = 0
-LIBPATCH = 7
+LIBPATCH = 8
 
 PYDEPS = ["cosl", "pydantic < 2"]
 
@@ -700,10 +700,18 @@ def metrics_jobs(self) -> List[Dict]:
 
                 # Apply labels to the scrape jobs
                 for static_config in job.get("static_configs", []):
+                    topo_as_dict = topology.as_dict(excluded_keys=["charm_name"])
                     static_config["labels"] = {
                         # Be sure to keep labels from static_config
                         **static_config.get("labels", {}),
-                        **topology.label_matcher_dict,
+                        # TODO: We should add a new method in juju_topology.py
+                        # that like `as_dict` method, returns the keys with juju_ prefix
+                        # https://github.com/canonical/cos-lib/issues/18
+                        **{
+                            "juju_{}".format(key): value
+                            for key, value in topo_as_dict.items()
+                            if value
+                        },
                     }
 
                 scrape_jobs.append(job)

lib/charms/loki_k8s/v1/loki_push_api.py

@@ -518,7 +518,7 @@ def _alert_rules_error(self, event):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 3
+LIBPATCH = 5
 
 logger = logging.getLogger(__name__)
 
@@ -799,7 +799,11 @@ def _from_file(self, root_path: Path, file_path: Path) -> List[dict]:
                         alert_rule["labels"] = {}
 
                     if self.topology:
-                        alert_rule["labels"].update(self.topology.label_matcher_dict)
+                        # only insert labels that do not already exist
+                        for label, val in self.topology.label_matcher_dict.items():
+                            if label not in alert_rule["labels"]:
+                                alert_rule["labels"][label] = val
+
                         # insert juju topology filters into a prometheus alert rule
                         # logql doesn't like empty matchers, so add a job matcher which hits
                         # any string as a "wildcard" which the topology labels will
@@ -2090,15 +2094,18 @@ def _download_and_push_promtail_to_workload(
             container: container into which promtail is to be uploaded.
         """
         # Check for Juju proxy variables and fall back to standard ones if not set
-        proxies: Optional[Dict[str, str]] = {}
-        if proxies and os.environ.get("JUJU_CHARM_HTTP_PROXY"):
-            proxies.update({"http": os.environ["JUJU_CHARM_HTTP_PROXY"]})
-        if proxies and os.environ.get("JUJU_CHARM_HTTPS_PROXY"):
-            proxies.update({"https": os.environ["JUJU_CHARM_HTTPS_PROXY"]})
-        if proxies and os.environ.get("JUJU_CHARM_NO_PROXY"):
-            proxies.update({"no_proxy": os.environ["JUJU_CHARM_NO_PROXY"]})
-        else:
-            proxies = None
+        # If no Juju proxy variable was set, we set proxies to None to let the ProxyHandler get
+        # the proxy env variables from the environment
+        proxies = {
+            # The ProxyHandler uses only the protocol names as keys
+            # https://docs.python.org/3/library/urllib.request.html#urllib.request.ProxyHandler
+            "https": os.environ.get("JUJU_CHARM_HTTPS_PROXY", ""),
+            "http": os.environ.get("JUJU_CHARM_HTTP_PROXY", ""),
+            # The ProxyHandler uses `no` for the no_proxy key
+            # https://github.com/python/cpython/blob/3.12/Lib/urllib/request.py#L2553
+            "no": os.environ.get("JUJU_CHARM_NO_PROXY", ""),
+        }
+        proxies = {k: v for k, v in proxies.items() if v != ""} or None
 
         proxy_handler = request.ProxyHandler(proxies)
         opener = request.build_opener(proxy_handler)