feat(loader): Add endpoint for dynamic SDK loader (#44346)

In this PR we add a new `JavaScriptSdkDynamicLoader` view that will
render the new dynamic js sdk loader as a template. This view does
nothing atm, but adding functionality will be the next step. Currently
this is not gated by the feature flag introduced with
#44228, but will be as soon as
it has complicated logic.

As a next step, we need to introduce a
`JS_SDK_DYNAMIC_LOADER_SDK_VERSION` config value, and then move to
adding project dsn settings for the dynamic loader.

Author: AbhiPrasad

src/sentry/api/endpoints/project_docs_platform.py

@@ -24,6 +24,10 @@ def replace_keys(html, project_key):
         "___RELAY_CDN_URL___",
         absolute_uri(reverse("sentry-js-sdk-loader", args=[project_key.public_key])),
     )
+    html = html.replace(
+        "___RELAY_DYNAMIC_CDN_URL___",
+        absolute_uri(reverse("sentry-js-sdk-dynamic-loader", args=[project_key.public_key])),
+    )
 
     # If we actually render this in the main UI we can also provide
     # extra information about the project (org slug and project slug)

src/sentry/api/serializers/models/project_key.py

@@ -30,6 +30,7 @@ def serialize(self, obj, attrs, user):
                 "minidump": obj.minidump_endpoint,
                 "unreal": obj.unreal_endpoint,
                 "cdn": obj.js_sdk_loader_cdn_url,
+                "dynamicCdn": obj.js_sdk_dynamic_loader_cdn_url,
             },
             "browserSdkVersion": get_selected_browser_sdk_version(obj),
             "browserSdk": {"choices": get_browser_sdk_version_choices()},

src/sentry/models/projectkey.py

@@ -227,7 +227,7 @@ def unreal_endpoint(self):
         return f"{self.get_endpoint()}/api/{self.project_id}/unreal/{self.public_key}/"
 
     @property
-    def js_sdk_loader_cdn_url(self):
+    def js_sdk_loader_cdn_url(self) -> str:
         if settings.JS_SDK_LOADER_CDN_URL:
             return f"{settings.JS_SDK_LOADER_CDN_URL}{self.public_key}.min.js"
         else:
@@ -237,6 +237,17 @@ def js_sdk_loader_cdn_url(self):
                 reverse("sentry-js-sdk-loader", args=[self.public_key, ".min"]),
             )
 
+    @property
+    def js_sdk_dynamic_loader_cdn_url(self) -> str:
+        if settings.JS_SDK_LOADER_CDN_URL:
+            return f"{settings.JS_SDK_LOADER_CDN_URL}dynamic/{self.public_key}.min.js"
+        else:
+            endpoint = self.get_endpoint()
+            return "{}{}".format(
+                endpoint,
+                reverse("sentry-js-sdk-dynamic-loader", args=[self.public_key, ".min"]),
+            )
+
     def get_endpoint(self, public=True):
         if public:
             endpoint = settings.SENTRY_PUBLIC_ENDPOINT or settings.SENTRY_ENDPOINT

src/sentry/web/frontend/js_sdk_dynamic_loader.py

@@ -0,0 +1,18 @@
+from rest_framework.request import Request
+from rest_framework.response import Response
+
+from sentry.web.frontend.base import BaseView
+
+
+class JavaScriptSdkDynamicLoader(BaseView):
+    auth_required = False
+
+    # Do not let an organization load trigger session, breaking Vary header.
+    # TODO: This view should probably not be a subclass of BaseView if it doesn't actually use the
+    # large amount of organization related support utilities, but that ends up being a large refactor.
+    def determine_active_organization(self, request: Request, organization_slug=None) -> None:
+        pass
+
+    def get(self, request: Request, public_key: str, minified: str) -> Response:
+        """Returns a JS file that dynamically loads the SDK based on project settings"""
+        return super().get(request)

src/sentry/web/urls.py

@@ -23,6 +23,7 @@
 from sentry.web.frontend.group_tag_export import GroupTagExportView
 from sentry.web.frontend.home import HomeView
 from sentry.web.frontend.idp_email_verification import AccountConfirmationView
+from sentry.web.frontend.js_sdk_dynamic_loader import JavaScriptSdkDynamicLoader
 from sentry.web.frontend.js_sdk_loader import JavaScriptSdkLoader
 from sentry.web.frontend.mailgun_inbound_webhook import MailgunInboundWebhookView
 from sentry.web.frontend.newest_performance_issue import NewestPerformanceIssueView
@@ -116,6 +117,12 @@
         JavaScriptSdkLoader.as_view(),
         name="sentry-js-sdk-loader",
     ),
+    # JavaScript SDK Dynamic Loader
+    url(
+        r"^js-sdk-loader/dynamic/(?P<public_key>[^/\.]+)(?:(?P<minified>\.min))?\.js$",
+        JavaScriptSdkDynamicLoader.as_view(),
+        name="sentry-js-sdk-dynamic-loader",
+    ),
     # Versioned API
     url(r"^api/0/", include("sentry.api.urls")),
     # Legacy unversioned endpoints

tests/sentry/models/test_projectkey.py

@@ -75,6 +75,20 @@ def test_get_dsn(self):
         assert key.csp_endpoint == "http://testserver/api/1/csp-report/?sentry_key=abc"
         assert key.minidump_endpoint == "http://testserver/api/1/minidump/?sentry_key=abc"
         assert key.unreal_endpoint == "http://testserver/api/1/unreal/abc/"
+        assert key.js_sdk_loader_cdn_url == "http://testserver/js-sdk-loader/abc.min.js"
+        assert (
+            key.js_sdk_dynamic_loader_cdn_url
+            == "http://testserver/js-sdk-loader/dynamic/abc.min.js"
+        )
+
+    def test_get_js_sdk_dynamic_loader_cdn_url_from_settings(self):
+        key = self.model(project_id=1, public_key="abc", secret_key="xyz")
+
+        with self.settings(JS_SDK_LOADER_CDN_URL="https://sentry-best-cdn.com/"):
+            assert (
+                key.js_sdk_dynamic_loader_cdn_url
+                == "https://sentry-best-cdn.com/dynamic/abc.min.js"
+            )
 
     def test_get_dsn_org_subdomain(self):
         with self.feature("organizations:org-subdomains"):

tests/sentry/web/frontend/test_js_sdk_dynamic_loader.py

@@ -0,0 +1,16 @@
+from django.conf import settings
+from django.urls import reverse
+
+from sentry.testutils import TestCase
+
+
+class JavaScriptSdkLoaderTest(TestCase):
+    def test_absolute_url(self):
+        assert (
+            reverse("sentry-js-sdk-dynamic-loader", args=[self.projectkey.public_key, ".min"])
+            in self.projectkey.js_sdk_dynamic_loader_cdn_url
+        )
+        settings.JS_SDK_LOADER_CDN_URL = "https://js.sentry-cdn.com/"
+        assert (
+            "https://js.sentry-cdn.com/dynamic/%s.min.js" % self.projectkey.public_key
+        ) == self.projectkey.js_sdk_dynamic_loader_cdn_url