get pyodide version from compat flag annotations, set pyodide-load-ex…

…ternal autogate on all python tests

src/workerd/io/compatibility-date.c++

@@ -296,4 +296,64 @@ kj::Maybe<kj::String> normalizeCompatDate(kj::StringPtr date) {
   return CompatDate::parse(date).map([](auto v) { return v.toString(); });
 }
 
+struct PythonSnapshotParsedField {
+  PythonSnapshotRelease::Reader pythonSnapshotRelease;
+  capnp::StructSchema::Field field;
+};
+
+kj::Array<const PythonSnapshotParsedField> makePythonSnapshotFieldTable(
+    capnp::StructSchema::FieldList fields) {
+  kj::Vector<PythonSnapshotParsedField> table(fields.size());
+
+  for (auto field: fields) {
+    kj::Maybe<PythonSnapshotRelease::Reader> maybePythonSnapshotRelease;
+
+    for (auto annotation: field.getProto().getAnnotations()) {
+      if (annotation.getId() == PYTHON_SNAPSHOT_RELEASE_ANNOTATION_ID) {
+        maybePythonSnapshotRelease =
+            annotation.getValue().getStruct().getAs<workerd::PythonSnapshotRelease>();
+      }
+    }
+
+    KJ_IF_SOME(pythonSnapshotRelease, maybePythonSnapshotRelease) {
+      table.add(PythonSnapshotParsedField{
+        .pythonSnapshotRelease = pythonSnapshotRelease,
+        .field = field,
+      });
+    }
+  }
+
+  return table.releaseAsArray();
+}
+
+kj::Maybe<PythonSnapshotRelease::Reader> getPythonSnapshotRelease(
+    CompatibilityFlags::Reader featureFlags) {
+  uint latestFieldOrdinal = 0;
+  kj::Maybe<PythonSnapshotRelease::Reader> result;
+
+  static auto fieldTable =
+      makePythonSnapshotFieldTable(capnp::Schema::from<CompatibilityFlags>().getFields());
+
+  for (auto field: fieldTable) {
+    bool isEnabled = capnp::toDynamic(featureFlags).get(field.field).as<bool>();
+    if (!isEnabled) {
+      continue;
+    }
+
+    // We pick the flag with the highest ordinal value that is enabled and has a
+    // pythonSnapshotRelease annotation.
+    //
+    // The fieldTable is probably ordered by the ordinal anyway, but doesn't hurt to be explicit
+    // here.
+    //
+    // TODO(later): make sure this is well tested once we have more than one compat flag.
+    if (latestFieldOrdinal < field.field.getIndex()) {
+      latestFieldOrdinal = field.field.getIndex();
+      result = field.pythonSnapshotRelease;
+    }
+  }
+
+  return result;
+}
+
 }  // namespace workerd

src/workerd/io/compatibility-date.h

@@ -50,6 +50,9 @@ kj::Maybe<kj::String> normalizeCompatDate(kj::StringPtr date);
 // Returns the current date as a string formatted by CompatDate.
 kj::String currentDateStr();
 
+kj::Maybe<PythonSnapshotRelease::Reader> getPythonSnapshotRelease(
+    CompatibilityFlags::Reader featureFlags);
+
 // These values come from src/workerd/io/compatibility-date.capnp
 static constexpr uint64_t COMPAT_ENABLE_FLAG_ANNOTATION_ID = 0xb6dabbc87cd1b03eull;
 static constexpr uint64_t COMPAT_DISABLE_FLAG_ANNOTATION_ID = 0xd145cf1adc42577cull;

src/workerd/server/tests/python/env-param/env.wd-test

@@ -18,4 +18,8 @@ const unitTests :Workerd.Config = (
       )
     ),
   ],
+
+  autogates = [
+    "workerd-autogate-pyodide-load-external",
+  ]
 );

src/workerd/server/tests/python/hello/hello.wd-test

@@ -12,4 +12,8 @@ const unitTests :Workerd.Config = (
       )
     ),
   ],
+
+  autogates = [
+    "workerd-autogate-pyodide-load-external",
+  ]
 );

src/workerd/server/tests/python/import_tests.bzl

@@ -27,6 +27,10 @@ const unitTests :Workerd.Config = (
       )
     ),
   ],
+
+  autogates = [
+    "workerd-autogate-pyodide-load-external",
+  ]
 );"""
 
 def generate_wd_test_file(requirement):

src/workerd/server/tests/python/langchain/langchain.wd-test

@@ -16,4 +16,8 @@ const unitTests :Workerd.Config = (
       )
     ),
   ],
+
+  autogates = [
+    "workerd-autogate-pyodide-load-external",
+  ]
 );

src/workerd/server/tests/python/random/random.wd-test

@@ -12,4 +12,8 @@ const unitTests :Workerd.Config = (
       )
     ),
   ],
+
+  autogates = [
+    "workerd-autogate-pyodide-load-external",
+  ]
 );

src/workerd/server/tests/python/subdirectory/subdirectory.wd-test

@@ -14,5 +14,9 @@ const unitTests :Workerd.Config = (
       )
     ),
   ],
+
+  autogates = [
+    "workerd-autogate-pyodide-load-external",
+  ]
 );
 

src/workerd/server/workerd-api.c++

@@ -499,7 +499,7 @@ bool fetchPyodideBundle(const api::pyodide::PythonConfig& pyConfig, kj::StringPt
 
       kj::HttpHeaders headers(table);
 
-      kj::String url = kj::str("https://pyodide.runtime-playground.workers.dev/python-runtime-capnp-bin/pyodide-", version, ".capnp.bin");
+      kj::String url = kj::str("https://pyodide.runtime-playground.workers.dev/pyodide-capnp-bin/pyodide-", version, ".capnp.bin");
 
       auto req = client->request(kj::HttpMethod::GET, kj::StringPtr(url), headers);
 
@@ -538,9 +538,10 @@ void WorkerdApi::compileModules(
           if (fetchPyodideBundle(impl->pythonConfig, "dev"_kj)) {
             modules->addBuiltinBundle(getPyodideBundle("dev"_kj), kj::none);
           } else {
-            // TODO: hardcoded version number
-            KJ_REQUIRE(fetchPyodideBundle(impl->pythonConfig, "2"_kj), "Failed to get both dev and hardcoded Pyodide version");
-            modules->addBuiltinBundle(getPyodideBundle("2"_kj), kj::none);
+            auto version = KJ_ASSERT_NONNULL(getPythonSnapshotRelease(featureFlags)).getPyodide();
+
+            KJ_REQUIRE(fetchPyodideBundle(impl->pythonConfig, version), "Failed to get Pyodide bundle");
+            modules->addBuiltinBundle(getPyodideBundle(version), kj::none);
           }
       }
       // Inject pyodide bootstrap module (TODO: load this from the capnproto bundle?)