Merge pull request #7 from canonical/webinteractor

store client: use in-house WebBrowserInteractor for candid (CRAFT-563)

.pylintrc

@@ -149,7 +149,8 @@ disable=print-statement,
         exception-escape,
         comprehension-escape,
         line-too-long,
-        fixme
+        fixme,
+        fixme-info
 
 # Enable the message, report, category or checker with the given id(s). You can
 # either give multiple identifier separated by comma (,) or put this option

craft_store/errors.py

@@ -76,3 +76,24 @@ class NotLoggedIn(CraftStoreError):
 
     def __init__(self, message: str) -> None:
         super().__init__(f"Not logged in: {message}.")
+
+
+class CandidTokenTimeoutError(CraftStoreError):
+    """Error raised when timeout is reached trying to discharge a macaroon."""
+
+    def __init__(self, url: str) -> None:
+        super().__init__(f"Timed out waiting for token response from {url!r}.")
+
+
+class CandidTokenKindError(CraftStoreError):
+    """Error raised when the token kind is missing from the discharged macaroon."""
+
+    def __init__(self, url: str) -> None:
+        super().__init__(f"Empty token kind returned from {url!r}.")
+
+
+class CandidTokenValueError(CraftStoreError):
+    """Error raised when the token value is missing from the discharged macaroon."""
+
+    def __init__(self, url: str) -> None:
+        super().__init__(f"Empty token value returned from {url!r}.")

craft_store/store_client.py

@@ -25,6 +25,7 @@
 from macaroonbakery import bakery, httpbakery
 from pymacaroons.serializers import json_serializer
 
+from . import errors
 from .auth import Auth
 from .http_client import HTTPClient
 
@@ -36,6 +37,40 @@ def _macaroon_to_json_string(macaroon) -> str:
     return macaroon.serialize(json_serializer.JsonSerializer())
 
 
+class WebBrowserWaitingInteractor(httpbakery.WebBrowserInteractor):
+    """WebBrowserInteractor implementation using HTTPClient.
+
+    Waiting for a token is implemented using HTTPClient which mounts
+    a session with backoff retries.
+
+    Better exception classes and messages are  provided to handle errors.
+    """
+
+    def __init__(self, user_agent: str) -> None:
+        super().__init__()
+        self.user_agent = user_agent
+
+    # TODO: transfer implementation to macaroonbakery.
+    def _wait_for_token(self, ctx, wait_token_url):
+        request_client = HTTPClient(user_agent=self.user_agent)
+        resp = request_client.request("GET", wait_token_url)
+        if resp.status_code != 200:
+            raise errors.CandidTokenTimeoutError(url=wait_token_url)
+        json_resp = resp.json()
+        kind = json_resp.get("kind")
+        if kind is None:
+            raise errors.CandidTokenKindError(url=wait_token_url)
+        token_val = json_resp.get("token")
+        if token_val is None:
+            token_val = json_resp.get("token64")
+            if token_val is None:
+                raise errors.CandidTokenValueError(url=wait_token_url)
+            token_val = base64.b64decode(token_val)
+        return httpbakery._interactor.DischargeToken(  # pylint: disable=W0212
+            kind=kind, value=token_val
+        )
+
+
 class StoreClient(HTTPClient):
     """Encapsulates API calls for the Snap Store or Charmhub."""
 
@@ -56,7 +91,9 @@ def __init__(
         """
         super().__init__(user_agent=user_agent)
 
-        self._bakery_client = httpbakery.Client()
+        self._bakery_client = httpbakery.Client(
+            interaction_methods=[WebBrowserWaitingInteractor(user_agent=user_agent)]
+        )
         self._base_url = base_url
         self._store_host = urlparse(base_url).netloc
         self._endpoints = endpoints
@@ -89,6 +126,7 @@ def _authorize_token(self, candid_discharged_macaroon: str) -> str:
             "POST",
             self._base_url + self._endpoints.tokens_exchange,
             headers={"Macaroons": candid_discharged_macaroon},
+            json={},
         )
 
         return token_exchange_response.json()["macaroon"]

setup.cfg

@@ -31,6 +31,7 @@ install_requires =
     pydantic
     keyring
     macaroonbakery
+    requests
 
 [options.package_data]
 craft_store = py.typed
@@ -96,6 +97,9 @@ ignore_missing_imports = True
 [mypy-pymacaroons.*]
 ignore_missing_imports = True
 
+[mypy-urllib3.*]
+ignore_missing_imports = True
+
 [pydantic-mypy]
 init_forbid_extra = True
 init_typed = True

tests/unit/test_errors.py

@@ -60,6 +60,21 @@ def _fake_error_response(status_code, reason):
         "args": ["no credentials"],
         "expected_message": "Not logged in: no credentials.",
     },
+    {
+        "exception_class": errors.CandidTokenTimeoutError,
+        "args": ["https://foo.bar"],
+        "expected_message": "Timed out waiting for token response from 'https://foo.bar'.",
+    },
+    {
+        "exception_class": errors.CandidTokenKindError,
+        "args": ["https://foo.bar"],
+        "expected_message": "Empty token kind returned from 'https://foo.bar'.",
+    },
+    {
+        "exception_class": errors.CandidTokenValueError,
+        "args": ["https://foo.bar"],
+        "expected_message": "Empty token value returned from 'https://foo.bar'.",
+    },
 )
 
 

tests/unit/test_store_client.py

@@ -15,14 +15,14 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import json
-from unittest.mock import Mock, call, patch
+from unittest.mock import ANY, Mock, call, patch
 
 import pytest
 from macaroonbakery import bakery, httpbakery
 from pymacaroons.macaroon import Macaroon
 
-from craft_store import endpoints
-from craft_store.store_client import StoreClient
+from craft_store import endpoints, errors
+from craft_store.store_client import StoreClient, WebBrowserWaitingInteractor
 
 
 def _fake_response(status_code, reason=None, json=None):
@@ -140,6 +140,7 @@ def test_store_client_login(
             headers={
                 "Macaroons": "W3siaWRlbnRpZmllciI6ICIiLCAic2lnbmF0dXJlIjogImQ5NTMzNDYxZDc4MzVlNDg1MWM3ZTNiNjM5MTQ0NDA2Y2Y3Njg1OTdkZWE2ZTEzMzIzMmZiZDIzODVhNWMwNTAiLCAibG9jYXRpb24iOiAiZmFrZS1zZXJ2ZXIuY29tIn1d"
             },
+            json={},
         ),
     ]
 
@@ -219,3 +220,56 @@ def test_store_client_whoami(http_client_request_mock, real_macaroon, auth_mock)
         call("fakecraft", "https://fake-server.com"),
         call().get_credentials(),
     ]
+
+
+def test_webinteractore_wait_for_token(http_client_request_mock):
+    http_client_request_mock.side_effect = None
+    http_client_request_mock.return_value = _fake_response(
+        200, json={"kind": "kind", "token": "TOKEN", "token64": b"VE9LRU42NA=="}
+    )
+
+    wbi = WebBrowserWaitingInteractor(user_agent="foobar")
+
+    discharged_token = wbi._wait_for_token(  # pylint: disable=W0212
+        object(), "https://foo.bar/candid"
+    )
+
+    assert discharged_token == httpbakery.DischargeToken(kind="kind", value="TOKEN")
+    assert http_client_request_mock.mock_calls == [
+        call(ANY, "GET", "https://foo.bar/candid")
+    ]
+
+
+def test_webinteractore_wait_for_token_timeout_error(http_client_request_mock):
+    http_client_request_mock.side_effect = None
+    http_client_request_mock.return_value = _fake_response(400, json={})
+
+    wbi = WebBrowserWaitingInteractor(user_agent="foobar")
+
+    with pytest.raises(errors.CandidTokenTimeoutError):
+        wbi._wait_for_token(object(), "https://foo.bar/candid")  # pylint: disable=W0212
+
+
+def test_webinteractore_wait_for_token_kind_error(http_client_request_mock):
+    http_client_request_mock.side_effect = None
+    http_client_request_mock.return_value = _fake_response(200, json={})
+
+    wbi = WebBrowserWaitingInteractor(user_agent="foobar")
+
+    with pytest.raises(errors.CandidTokenKindError):
+        wbi._wait_for_token(object(), "https://foo.bar/candid")  # pylint: disable=W0212
+
+
+def test_webinteractore_wait_for_token_value_error(http_client_request_mock):
+    http_client_request_mock.side_effect = None
+    http_client_request_mock.return_value = _fake_response(
+        200,
+        json={
+            "kind": "kind",
+        },
+    )
+
+    wbi = WebBrowserWaitingInteractor(user_agent="foobar")
+
+    with pytest.raises(errors.CandidTokenValueError):
+        wbi._wait_for_token(object(), "https://foo.bar/candid")  # pylint: disable=W0212

tox.ini

@@ -22,3 +22,6 @@ commands = make test-integrations
 
 [testenv:units]
 commands = make test-units
+
+[pycodestyle]
+ignore = E501