new relation to pass gateway info (#83)

* new relation to pass gateway info

* set model name in unit test

* fix lint

* remove debug code

* remove list comprehension for getting relations

* charm library for relation

* add lib to pythonpath
- clean up libraries
- update test

* use resource handler to create crd
or else lightkube would complain about same crd with diff signature
when using create_global_resource

* update receiver file

* fix tests

* PR review updates:
- merge charm lib files
- rename interface

* update comment

* use separate light kube client

* put mocker in fixture

* add doc

* pin dep

* fix istio-gateway not building in ci

* mock validate function instead of lightkube client

* remove relation len check

* mock lightkube client

* WIP take provider out of lib

* rename method
- only check for leadership at init
- rename gatewayprovider method
- update tests

* fix lint

* add info log if gateway relation data not sent

charms/istio-gateway/charmcraft.yaml

@@ -1,11 +1,11 @@
 type: charm
 bases:
   - build-on:
-    - name: "ubuntu"
-      channel: "20.04"
+      - name: 'ubuntu'
+        channel: '20.04'
     run-on:
-    - name: "ubuntu"
-      channel: "20.04"
+      - name: 'ubuntu'
+        channel: '20.04'
 parts:
   charm:
     # Remove when pypa/setuptools_scm#713 gets fixed

charms/istio-pilot/lib/charms/istio_pilot/v0/istio_gateway_name.py

@@ -0,0 +1,121 @@
+"""Library for sharing istio gateway information
+
+This library wraps the relation endpoints using the `istio-gateway-name`
+interface. It provides a Python API for both requesting and providing 
+gateway information.
+
+## Getting Started
+
+### Fetch library with charmcraft
+You can fetch the library using the following commands with charmcraft.
+```shell
+cd some-charm
+charmcraft fetch-lib charms.istio_pilot.v0.istio_gateway_name
+```
+### Add relation to metadata.yaml
+```yaml
+requires:
+    gateway:
+        interface: istio_gateway_name
+        limit: 1
+```
+
+### Initialise the library in charm.py
+```python
+from charms.istio_pilot.v0.istio_gateway_name import GatewayProvider, GatewayRelationError
+
+Class SomeCharm(CharmBase):
+    def __init__(self, *args):
+        self.gateway = GatewayProvider(self)
+        self.framework.observe(self.on.some_event_emitted, self.some_event_function)
+
+    def some_event_function():
+        # use the getter function wherever the info is needed
+        try:
+            gateway_data = self.gateway_relation.get_relation_data()
+            except GatewayRelationError as error:
+            ...
+```
+"""
+
+import logging
+from ops.framework import Object
+from ops.model import Application
+
+# Increment this major API version when introducing breaking changes
+LIBAPI = 0
+
+# Increment this PATCH version before using `charmcraft publish-lib` or reset
+# to 0 if you are raising the major API version
+LIBPATCH = 1
+
+
+DEFAULT_RELATION_NAME = "gateway"
+DEFAULT_INTERFACE_NAME = "istio-gateway-name"
+
+logger = logging.getLogger(__name__)
+
+
+class GatewayRelationError(Exception):
+    pass
+
+
+class GatewayRelationMissingError(GatewayRelationError):
+    def __init__(self):
+        self.message = "Missing gateway relation with istio-pilot"
+        super().__init__(self.message)
+
+
+class GatewayRelationTooManyError(GatewayRelationError):
+    def __init__(self):
+        self.message = "Too many istio-gateway-name relations"
+        super().__init__(self.message)
+
+
+class GatewayRelationDataMissingError(GatewayRelationError):
+    def __init__(self, message):
+        self.message = message
+        super().__init__(self.message)
+
+
+class GatewayRequirer(Object):
+    def __init__(self, charm, relation_name: str = DEFAULT_RELATION_NAME):
+        super().__init__(charm, relation_name)
+        self.charm = charm
+        self.relation_name = relation_name
+
+    def get_relation_data(self):
+        if not self.model.unit.is_leader():
+            return
+        gateway = self.model.relations[self.relation_name]
+        if len(gateway) == 0:
+            raise GatewayRelationMissingError()
+        if len(gateway) > 1:
+            raise GatewayRelationTooManyError()
+
+        remote_app = [
+            app
+            for app in gateway[0].data.keys()
+            if isinstance(app, Application) and not app._is_our_app
+        ][0]
+
+        data = gateway[0].data[remote_app]
+
+        if not "gateway_name" in data:
+            logger.error(
+                "Missing gateway name in gateway relation data. Waiting for gateway creation in istio-pilot"
+            )
+            raise GatewayRelationDataMissingError(
+                "Missing gateway name in gateway relation data. Waiting for gateway creation in istio-pilot"
+            )
+
+        if not "gateway_namespace" in data:
+            logger.error("Missing gateway namespace in gateway relation data")
+            raise GatewayRelationDataMissingError(
+                "Missing gateway namespace in gateway relation data"
+            )
+
+        return {
+            "gateway_name": data["gateway_name"],
+            "gateway_namespace": data["gateway_namespace"],
+        }

charms/istio-pilot/metadata.yaml

@@ -17,5 +17,9 @@ provides:
     interface: ingress-auth
     schema: https://raw.githubusercontent.com/canonical/operator-schemas/master/ingress-auth.yaml
     versions: [v1]
+  gateway:
+    interface: istio-gateway-name
+    description: |
+      Provides gateway name related Juju application
 assumes:
   - juju >= 2.9.0

charms/istio-pilot/requirements.txt

@@ -2,6 +2,7 @@ jinja2<3.1
 ops<1.4.0
 requests<2.27.0
 serialized-data-interface<0.4
+oci-image
 
 # Temporarily using ca-scribner's branch that adds implicit custom
 # resource creation. Change this after those changes get merged into master

charms/istio-pilot/src/charm.py

@@ -13,6 +13,7 @@
 from ops.model import ActiveStatus, BlockedStatus, WaitingStatus
 from serialized_data_interface import NoCompatibleVersions, NoVersionsListed, get_interfaces
 from resources_handler import ResourceHandler
+from istio_gateway_name_provider import GatewayProvider, DEFAULT_RELATION_NAME
 
 
 class Operator(CharmBase):
@@ -45,12 +46,16 @@ def __init__(self, *args):
             "auth_filter.yaml.j2",
             "virtual_service.yaml.j2",
         ]
+        self.gateway = GatewayProvider(self)
 
         self.framework.observe(self.on.install, self.install)
         self.framework.observe(self.on.remove, self.remove)
 
         self.framework.observe(self.on.config_changed, self.handle_default_gateway)
 
+        self.framework.observe(
+            self.on[DEFAULT_RELATION_NAME].relation_changed, self.handle_default_gateway
+        )
         self.framework.observe(self.on["istio-pilot"].relation_changed, self.send_info)
         self.framework.observe(self.on['ingress'].relation_changed, self.handle_ingress)
         self.framework.observe(self.on['ingress'].relation_broken, self.handle_ingress)
@@ -126,6 +131,24 @@ def handle_default_gateway(self, event):
         # Update the ingress resources as they rely on the default_gateway
         self.handle_ingress(event)
 
+        # check if gateway is created
+        self.handle_gateway_relation(event)
+
+    def handle_gateway_relation(self, event):
+        is_gateway_created = self._resource_handler.validate_resource_exist(
+            resource_type=self._resource_handler.get_custom_resource_class_from_filename(
+                "gateway.yaml.j2"
+            ),
+            resource_name=self.model.config['default-gateway'],
+            resource_namespace=self.model.name,
+        )
+        if is_gateway_created:
+            self.gateway.send_gateway_relation_data(
+                self.app, self.model.config['default-gateway'], self.model.name
+            )
+        else:
+            self.log.info("Gateway is not created yet. Skip sending gateway relation data.")
+
     def send_info(self, event):
         if self.interfaces["istio-pilot"]:
             self.interfaces["istio-pilot"].send_data(

charms/istio-pilot/src/istio_gateway_name_provider.py

@@ -0,0 +1,21 @@
+import logging
+from ops.framework import Object
+
+logger = logging.getLogger(__name__)
+
+DEFAULT_RELATION_NAME = "gateway"
+
+
+class GatewayProvider(Object):
+    def __init__(self, charm, relation_name=DEFAULT_RELATION_NAME):
+        super().__init__(charm, relation_name)
+
+    def send_gateway_relation_data(self, charm, gateway_name, gateway_namespace):
+        relations = self.model.relations["gateway"]
+        for relation in relations:
+            relation.data[charm].update(
+                {
+                    "gateway_name": gateway_name,
+                    "gateway_namespace": gateway_namespace,
+                }
+            )

charms/istio-pilot/src/resources_handler.py

@@ -89,6 +89,15 @@ def delete_manifest(
                 ignore_unauthorized=ignore_unauthorized,
             )
 
+    def validate_resource_exist(self, resource_type, resource_name, resource_namespace):
+        try:
+            self.lightkube_client.get(resource_type, resource_name, namespace=resource_namespace)
+            return True
+        except ApiError as error:
+            self.log.error(str(error))
+
+        return False
+
     def get_custom_resource_class_from_filename(self, filename: str):
         """Returns a class representing a namespaced K8s resource.
 

charms/istio-pilot/tests/unit/test_charm.py

@@ -343,6 +343,34 @@ def test_with_ingress_auth_relation(harness, subprocess, helpers, mocked_client,
     assert isinstance(harness.charm.model.unit.status, ActiveStatus)
 
 
+def test_correct_data_in_gateway_relation(harness, mocker, mocked_client):
+    harness.set_leader(True)
+
+    create_global_resource(
+        group="networking.istio.io",
+        version="v1beta1",
+        kind="Gateway",
+        plural="gateways",
+        verbs=None,
+    )
+
+    mocked_validate_gateway = mocker.patch(
+        "resources_handler.ResourceHandler.validate_resource_exist"
+    )
+    mocked_validate_gateway.return_value = True
+
+    rel_id = harness.add_relation("gateway", "app")
+    harness.add_relation_unit(rel_id, "app/0")
+    harness.set_model_name("test-model")
+    harness.begin_with_initial_hooks()
+
+    gateway_relations = harness.model.relations["gateway"]
+    istio_relation_data = gateway_relations[0].data[harness.model.app]
+
+    assert istio_relation_data["gateway_name"] == harness.model.config["default-gateway"]
+    assert istio_relation_data["gateway_namespace"] == harness.model.name
+
+
 def test_removal(harness, subprocess, mocked_client, helpers, mocker):
     check_output = subprocess.check_output
 
@@ -374,8 +402,6 @@ def test_removal(harness, subprocess, mocked_client, helpers, mocker):
         f"values.global.istioNamespace={None}",
     ]
 
-    # Create the gateway resource and emit config_changed
-    # to create all needed resources
     create_global_resource(
         group="networking.istio.io",
         version="v1beta1",

charms/istio-pilot/tox.ini

@@ -1,24 +1,31 @@
 [flake8]
 max-line-length = 100
 
+[vars]
+src_path = {toxinidir}/src
+tst_path = {toxinidir}/tests
+all_path = {[vars]src_path} {[vars]tst_path}
+
+
 [tox]
 skipsdist = True
 
 [testenv]
 setenv =
-    PYTHONPATH={toxinidir}/src
+    PYTHONPATH = {toxinidir}:{toxinidir}/lib:{[vars]src_path}
+passenv =
+    PYTHONPATH
+    CHARM_BUILD_DIR
+    MODEL_SETTINGS
 deps =
     -rtest-requirements.txt
     -rrequirements.txt
 
 [testenv:unit]
 commands =
-    pytest tests/unit {posargs}
-
-[vars]
-paths = {toxinidir}/src {toxinidir}/tests
+    pytest {[vars]tst_path}/unit -v --tb native -s {posargs}
 
 [testenv:lint]
 commands =
-    flake8 {[vars]paths}
-    black --check {[vars]paths}
+    flake8 {[vars]all_path}
+    black --check {[vars]all_path}