feat: enable Lix admins to admin the Buildbot properly

This removes the need for a proxy and rely on the `groups` property of
the `userDetails` passed at the authentication layer.

To add a certain role, add the group `buildbot-$role` to that user via
Keycloak.

Signed-off-by: Raito Bezarius <raito@lix.systems>

buildbot_nix/__init__.py

@@ -9,6 +9,7 @@ from dataclasses import dataclass
 from pathlib import Path
 from typing import TYPE_CHECKING, Any
 
+import buildbot
 from buildbot.configurators import ConfiguratorBase
 from buildbot.plugins import reporters, schedulers, secrets, steps, util, worker
 from buildbot.process import buildstep, logobserver, remotecommand
@@ -17,7 +18,6 @@ from buildbot.process.properties import Interpolate, Properties
 from buildbot.process.results import ALL_RESULTS, statusToString
 from buildbot.steps.trigger import Trigger
 from buildbot.util import asyncSleep
-from buildbot.www.authz.endpointmatchers import EndpointMatcherBase, Match
 from buildbot.www.oauth2 import OAuth2Auth
 from buildbot.changes.gerritchangesource import GerritChangeSource
 from buildbot.reporters.utils import getURLForBuild
@@ -27,6 +27,7 @@ from buildbot.process.buildstep import EXCEPTION
 from buildbot.process.buildstep import SUCCESS
 from buildbot.process.results import worst_status
 from buildbot_nix.binary_cache import LocalSigner
+import requests
 
 if TYPE_CHECKING:
     from buildbot.process.log import Log
@@ -46,11 +47,33 @@ log = Logger()
 class LixSystemsOAuth2(OAuth2Auth):
     name = 'Lix'
     faIcon = 'fa-login'
-    resourceEndpoint = "https://identity.lix.systems"
-    # is passing scope necessary?
+    resourceEndpoint = "https://identity.lix.systems/realms/lix-project/protocol/openid-connect"
+    sslVerify = True
+    debug = False
     authUri = 'https://identity.lix.systems/realms/lix-project/protocol/openid-connect/auth'
     tokenUri = 'https://identity.lix.systems/realms/lix-project/protocol/openid-connect/token'
 
+    def createSessionFromToken(self, token):
+        s = requests.Session()
+        s.headers = {
+            'Authorization': 'Bearer ' + token['access_token'],
+            'User-Agent': f'buildbot/{buildbot.version}',
+        }
+        if self.debug:
+            log.info("Token obtained: {}".format(token))
+        s.verify = self.sslVerify
+        return s
+
+    def getUserInfoFromOAuthClient(self, c):
+        userinfo_resp = c.get("https://identity.lix.systems/realms/lix-project/protocol/openid-connect/userinfo")
+        log.info("Userinfo request to Lix OAuth2: {}".format(userinfo_resp.status_code))
+        if userinfo_resp.status_code != 200:
+            log.info("Userinfo failure: {}".format(userinfo_resp.headers["www-authenticate"]))
+        userinfo_data = userinfo_resp.json()
+        return {
+            'groups': userinfo_data['buildbot_roles']
+        }
+
 class BuildbotNixError(Exception):
     pass
 
@@ -901,3 +924,18 @@ class GerritNixConfigurator(ConfiguratorBase):
 
         if "auth" not in config["www"]:
             config["www"]["auth"] = LixSystemsOAuth2('buildbot', read_secret_file('buildbot-oauth2-secret'), autologin=True)
+
+        if "authz" not in config["www"]:
+            config["www"]["authz"] = util.Authz(
+                allowRules=[
+                    util.AnyEndpointMatcher(role="admin", defaultDeny=False),
+                    util.StopBuildEndpointMatcher(role="owner"),
+                    util.AnyControlEndpointMatcher(role="admin"),
+                ],
+                roleMatchers=[
+                    # A user must have buildbot-<something> to have the role <something>
+                    # e.g. buildbot-admin to be admin.
+                    util.RolesFromGroups(groupPrefix="buildbot-"),
+                    util.RolesFromOwner(role="owner")
+                ],
+            )