feat: better errors when unsupported packages are requested

dom96 · dom96 · commit e5000eded90f · 2025-10-31T12:02:40.000Z
diff --git a/src/pywrangler/sync.py b/src/pywrangler/sync.py
@@ -177,7 +177,7 @@ def _install_requirements_to_vendor(requirements: list[str]) -> None:
         extra={"markup": True},
     )
     with temp_requirements_file(requirements) as requirements_file:
-        run_command(
+        result = run_command(
             [
                 "uv",
                 "pip",
@@ -190,8 +190,31 @@ def _install_requirements_to_vendor(requirements: list[str]) -> None:
                 "--index-strategy",
                 "unsafe-best-match",
             ],
+            capture_output=True,
+            check=False,
             env=os.environ | {"VIRTUAL_ENV": get_pyodide_venv_path()},
         )
+        if result.returncode != 0:
+            logger.warning(result.stdout.strip())
+            # Handle some common failures and give nicer error messages for them.
+            lowered_stdout = result.stdout.lower()
+            if "invalid peer certificate" in lowered_stdout:
+                logger.error(
+                    "Installation failed because of an invalid peer certificate. Are your systems certificates correctly installed? Do you have an Enterprise VPN enabled?"
+                )
+            elif "failed to fetch" in lowered_stdout:
+                logger.error(
+                    "Installation failed because of a failed fetch. Is your network connection working?"
+                )
+            elif "no solution found when resolving dependencies" in lowered_stdout:
+                logger.error(
+                    "Installation failed because the packages you requested are not supported by Python Workers. See above for details."
+                )
+            else:
+                logger.error(
+                    "Installation of packages into the Python Worker failed. Possibly because these packages are not currently supported. See above for details."
+                )
+            raise click.exceptions.Exit(code=result.returncode)
         pyv = get_python_version()
         shutil.rmtree(vendor_path)
         shutil.copytree(
@@ -221,16 +244,24 @@ def _install_requirements_to_venv(requirements: list[str]) -> None:
         extra={"markup": True},
     )
     with temp_requirements_file(requirements) as requirements_file:
-        run_command(
+        result = run_command(
             [
                 "uv",
                 "pip",
                 "install",
                 "-r",
                 requirements_file,
             ],
+            check=False,
             env=os.environ | {"VIRTUAL_ENV": venv_workers_path},
+            capture_output=True,
         )
+        if result.returncode != 0:
+            logger.warning(result.stdout.strip())
+            logger.error(
+                "Failed to install the requirements defined in your pyproject.toml file. See above for details."
+            )
+            raise click.exceptions.Exit(code=result.returncode)
 
     get_venv_workers_token_path().touch()
     logger.info(
@@ -240,8 +271,14 @@ def _install_requirements_to_venv(requirements: list[str]) -> None:
 
 
 def install_requirements(requirements: list[str]) -> None:
-    _install_requirements_to_vendor(requirements)
+    # Note: the order these are executed is important.
+    # We need to install to .venv-workers first, so that we can determine if the packages requested
+    # by the user are valid.
     _install_requirements_to_venv(requirements)
+    # Then we install the same requirements to the vendor directory. If this installation
+    # fails while the above succeeded, it implies that Pyodide does not support these package
+    # requirements which allows us to give a nicer error message to the user.
+    _install_requirements_to_vendor(requirements)
 
 
 def _is_out_of_date(token: Path, time: float) -> bool:
diff --git a/src/pywrangler/utils.py b/src/pywrangler/utils.py
@@ -79,20 +79,24 @@ def run_command(
     """
     logger.log(RUNNING_LEVEL, f"{' '.join(str(arg) for arg in command)}")
     try:
+        kwargs = {}
+        if capture_output:
+            kwargs = dict(stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+
         process = subprocess.run(
             command,
             cwd=cwd,
             env=env,
             check=check,
-            capture_output=capture_output,
             text=True,
-        )
+            **kwargs,
+        )  # type: ignore[call-overload]
         if process.stdout and not capture_output:
             logger.log(OUTPUT_LEVEL, f"{process.stdout.strip()}")
-        return process
+        return process  # type: ignore[no-any-return]
     except subprocess.CalledProcessError as e:
         logger.error(
-            f"Error running command: {' '.join(str(arg) for arg in command)}\nExit code: {e.returncode}\nOutput:\n{e.stdout.strip() if e.stdout else ''}{e.stderr.strip() if e.stderr else ''}"
+            f"Error running command: {' '.join(str(arg) for arg in command)}\nExit code: {e.returncode}\nOutput:\n{e.stdout.strip() if e.stdout else ''}"
         )
         raise click.exceptions.Exit(code=e.returncode) from None
     except FileNotFoundError:
