Update libraries (#106)

* Update libraries

* Fetch `prometheus_scrape`, too

lib/charms/prometheus_k8s/v0/prometheus_scrape.py

@@ -1,6 +1,8 @@
 # Copyright 2021 Canonical Ltd.
 # See LICENSE file for licensing details.
-"""## Overview.
+"""Source code can be found on GitHub at canonical/observability-libs/lib/charms/observability_libs.
+
+## Overview
 
 This document explains how to integrate with the Prometheus charm
 for the purpose of providing a metrics endpoint to Prometheus. It
@@ -11,6 +13,13 @@
 shared between Prometheus charms and any other charm that intends to
 provide a scrape target for Prometheus.
 
+## Dependencies
+
+Using this library requires you to fetch the juju_topology library from
+[observability-libs](https://charmhub.io/observability-libs/libraries/juju_topology).
+
+`charmcraft fetch-lib charms.observability_libs.v0.juju_topology`
+
 ## Provider Library Usage
 
 This Prometheus charm interacts with its scrape targets using its
@@ -341,7 +350,7 @@ def _on_scrape_targets_changed(self, event):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 23
+LIBPATCH = 24
 
 logger = logging.getLogger(__name__)
 
@@ -1516,10 +1525,11 @@ def __init__(
         self.external_url = external_url
 
         events = self._charm.on[self._relation_name]
-        self.framework.observe(events.relation_joined, self._set_scrape_job_spec)
         self.framework.observe(events.relation_changed, self._on_relation_changed)
 
         if not refresh_event:
+            # FIXME remove once podspec charms are verified.
+            # `self._set_scrape_job_spec()` is called every re-init so this should not be needed.
             if len(self._charm.meta.containers) == 1:
                 if "kubernetes" in self._charm.meta.series:
                     # This is a podspec charm
@@ -1544,10 +1554,16 @@ def __init__(
         for ev in refresh_event:
             self.framework.observe(ev, self._set_scrape_job_spec)
 
-        self.framework.observe(self._charm.on.upgrade_charm, self._set_scrape_job_spec)
-
-        # If there is no leader during relation_joined we will still need to set alert rules.
-        self.framework.observe(self._charm.on.leader_elected, self._set_scrape_job_spec)
+        # Update relation data every reinit. If instead we used event hooks then observing only
+        # relation-joined would not be sufficient:
+        # - Would need to observe leader-elected, in case there was no leader during
+        #   relation-joined.
+        # - If later related to an ingress provider, then would need to register and wait for
+        #   update-status interval to elapse before changes would apply.
+        # - The ingerss-ready custom event is currently emitted prematurely and cannot be relied
+        #   upon: https://github.com/canonical/traefik-k8s-operator/issues/78
+        # NOTE We may still end up waiting for update-status before changes are applied.
+        self._set_scrape_job_spec()
 
     def _on_relation_changed(self, event):
         """Check for alert rule messages in the relation data before moving on."""
@@ -1563,9 +1579,7 @@ def _on_relation_changed(self, event):
                 else:
                     self.on.alert_rule_status_changed.emit(valid=valid, errors=errors)
 
-        self._set_scrape_job_spec(event)
-
-    def _set_scrape_job_spec(self, event):
+    def _set_scrape_job_spec(self, _=None):
         """Ensure scrape target information is made available to prometheus.
 
         When a metrics provider charm is related to a prometheus charm, the
@@ -1574,7 +1588,7 @@ def _set_scrape_job_spec(self, event):
         data. In addition, each of the consumer units also sets its own
         host address in Juju unit relation data.
         """
-        self._set_unit_ip(event)
+        self._set_unit_ip()
 
         if not self._charm.unit.is_leader():
             return
@@ -1594,7 +1608,7 @@ def _set_scrape_job_spec(self, event):
                 # that is written to the filesystem.
                 relation.data[self._charm.app]["alert_rules"] = json.dumps(alert_rules_as_dict)
 
-    def _set_unit_ip(self, _):
+    def _set_unit_ip(self, _=None):
         """Set unit host address.
 
         Each time a metrics provider charm container is restarted it updates its own

lib/charms/traefik_k8s/v1/ingress.py

@@ -54,7 +54,7 @@ def _on_ingress_revoked(self, event: IngressPerAppRevokedEvent):
 import logging
 import socket
 import typing
-from typing import Any, Dict, Optional, Tuple
+from typing import Any, Dict, Optional, Tuple, Union
 
 import yaml
 from ops.charm import CharmBase, RelationBrokenEvent, RelationEvent
@@ -69,7 +69,7 @@ def _on_ingress_revoked(self, event: IngressPerAppRevokedEvent):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 3
+LIBPATCH = 4
 
 DEFAULT_RELATION_NAME = "ingress"
 RELATION_INTERFACE = "ingress"
@@ -97,6 +97,7 @@ def _on_ingress_revoked(self, event: IngressPerAppRevokedEvent):
         "name": {"type": "string"},
         "host": {"type": "string"},
         "port": {"type": "string"},
+        "strip-prefix": {"type": "string"},
     },
     "required": ["model", "name", "host", "port"],
 }
@@ -115,7 +116,11 @@ def _on_ingress_revoked(self, event: IngressPerAppRevokedEvent):
     from typing_extensions import TypedDict  # py35 compat
 
 # Model of the data a unit implementing the requirer will need to provide.
-RequirerData = TypedDict("RequirerData", {"model": str, "name": str, "host": str, "port": int})
+RequirerData = TypedDict(
+    "RequirerData",
+    {"model": str, "name": str, "host": str, "port": int, "strip-prefix": bool},
+    total=False,
+)
 # Provider ingress data model.
 ProviderIngressData = TypedDict("ProviderIngressData", {"url": str})
 # Provider application databag model.
@@ -221,12 +226,14 @@ def restore(self, snapshot: dict) -> None:
 class IngressPerAppDataProvidedEvent(_IPAEvent):
     """Event representing that ingress data has been provided for an app."""
 
-    __args__ = ("name", "model", "port", "host")
+    __args__ = ("name", "model", "port", "host", "strip_prefix")
+
     if typing.TYPE_CHECKING:
         name = None  # type: str
         model = None  # type: str
         port = None  # type: int
         host = None  # type: str
+        strip_prefix = False  # type: bool
 
 
 class IngressPerAppDataRemovedEvent(RelationEvent):
@@ -266,6 +273,7 @@ def _handle_relation(self, event):
                 data["model"],
                 data["port"],
                 data["host"],
+                data.get("strip-prefix", False),
             )
 
     def _handle_relation_broken(self, event):
@@ -297,17 +305,14 @@ def _get_requirer_data(self, relation: Relation) -> RequirerData:
             return {}
 
         databag = relation.data[relation.app]
-        try:
-            remote_data = {k: databag[k] for k in ("model", "name", "host", "port")}
-        except KeyError as e:
-            # incomplete data / invalid data
-            log.debug("error {}; ignoring...".format(e))
-            return {}
-        except TypeError as e:
-            raise DataValidationError("Error casting remote data: {}".format(e))
+        remote_data = {}  # type: Dict[str, Union[int, str]]
+        for k in ("port", "host", "model", "name", "mode", "strip-prefix"):
+            v = databag.get(k)
+            if v is not None:
+                remote_data[k] = v
         _validate_data(remote_data, INGRESS_REQUIRES_APP_SCHEMA)
-
         remote_data["port"] = int(remote_data["port"])
+        remote_data["strip-prefix"] = bool(remote_data.get("strip-prefix", False))
         return remote_data
 
     def get_data(self, relation: Relation) -> RequirerData:
@@ -408,6 +413,7 @@ def __init__(
         *,
         host: str = None,
         port: int = None,
+        strip_prefix: bool = False,
     ):
         """Constructor for IngressRequirer.
 
@@ -422,13 +428,15 @@ def __init__(
                 relation must be of interface type `ingress` and have "limit: 1")
             host: Hostname to be used by the ingress provider to address the requiring
                 application; if unspecified, the default Kubernetes service name will be used.
+            strip_prefix: configure Traefik to strip the path prefix.
 
         Request Args:
             port: the port of the service
         """
         super().__init__(charm, relation_name)
         self.charm: CharmBase = charm
         self.relation_name = relation_name
+        self._strip_prefix = strip_prefix
 
         self._stored.set_default(current_url=None)
 
@@ -501,6 +509,10 @@ def provide_ingress_requirements(self, *, host: str = None, port: int):
             "host": host,
             "port": str(port),
         }
+
+        if self._strip_prefix:
+            data["strip_prefix"] = "true"
+
         _validate_data(data, INGRESS_REQUIRES_APP_SCHEMA)
         self.relation.data[self.app].update(data)