Merge pull request #1492 from cloudflare/dominik/pyodide-bootstrap-in…

…-workerd

Introduces Pyodide bootstrap files.

src/pyodide/BUILD.bazel

@@ -36,11 +36,9 @@ expand_template(
 
 wd_js_bundle(
     name = "pyodide",
-    builtin_modules = glob(
-        [
-            "*.js",
-        ],
-    ),
+    builtin_modules = [
+        "python.js",
+    ],
     import_name = "pyodide",
     internal_data_modules = ["generated/python_stdlib.zip"],
     internal_modules = [

src/pyodide/internal/pyodide-bootstrap.js

@@ -0,0 +1,76 @@
+import { loadPyodide } from "pyodide:python";
+import { getMetadata } from "pyodide:current-bundle";
+import { lockFile } from "pyodide:package-lock.json";
+
+function initializePackageIndex(pyodide, lockfile) {
+  if (!lockfile.packages) {
+    throw new Error(
+      "Loaded pyodide lock file does not contain the expected key 'packages'.",
+    );
+  }
+  const API = pyodide._api;
+  API.config.indexURL = "https://cdn.jsdelivr.net/pyodide/v0.25.0a1/full/";
+  globalThis.location = "https://cdn.jsdelivr.net/pyodide/v0.25.0a1/full/";
+  API.lockfile_info = lockfile.info;
+  API.lockfile_packages = lockfile.packages;
+  API.repodata_packages = lockfile.packages;
+  API.repodata_info = lockfile.info;
+  API.lockfile_unvendored_stdlibs_and_test = [];
+
+  // compute the inverted index for imports to package names
+  API._import_name_to_package_name = new Map();
+  for (let name of Object.keys(API.lockfile_packages)) {
+    const pkg = API.lockfile_packages[name];
+
+    for (let import_name of pkg.imports) {
+      API._import_name_to_package_name.set(import_name, name);
+    }
+
+    if (pkg.package_type === "cpython_module") {
+      API.lockfile_unvendored_stdlibs_and_test.push(name);
+    }
+  }
+
+  API.lockfile_unvendored_stdlibs =
+    API.lockfile_unvendored_stdlibs_and_test.filter((lib) => lib !== "test");
+
+  const origLoadPackage = pyodide.loadPackage;
+  pyodide.loadPackage = async function (packages, options) {
+    // Must disable check integrity:
+    // Subrequest integrity checking is not implemented. The integrity option
+    // must be either undefined or an empty string.
+    return await origLoadPackage(packages, {
+      checkIntegrity: false,
+      ...options,
+    });
+  };
+}
+
+export default {
+  async fetch(request, env) {
+    // The metadata is a JSON-serialised WorkerBundle (defined in pipeline.capnp).
+    const metadata = getMetadata();
+
+    const pyodide = await loadPyodide();
+    initializePackageIndex(pyodide, lockFile);
+    // Loop through globals that define Python modules in the metadata passed to our Worker. For
+    // each one, save it in Pyodide's file system.
+    const pythonRequirements = [];
+    for (const { name, value } of metadata.globals) {
+      if (value.pythonModule !== undefined) {
+        pyodide.FS.writeFile(`/session/${name}.py`, value.pythonModule, {
+          canOwn: true,
+        });
+      }
+
+      if (value.pythonRequirement !== undefined) {
+        pythonRequirements.push(name);
+      }
+    }
+    await pyodide.loadPackage(pythonRequirements);
+
+    const result = await pyodide.pyimport(metadata.mainModule).fetch(request);
+
+    return result;
+  },
+};