PYTHON: Depends on node.js installation

[srgoni]

Expected Behavior

When executing a cdktf stack script written in Python directly, it should run without requiring any dependencies besides the cdktf Python modules and precompiled providers.

Actual Behavior

The script fails with a FileNotFoundError: [Errno 2] No such file or directory: 'node' error, indicating that the Python modules will always try to spawn an external Node.js interpreter.

Steps to Reproduce

1. Create a basic Python cdktf script:

# main.py
from cdktf import App, TerraformStack
app = App()
TerraformStack(app, "test")
app.synth()

2. Install dependencies:

pipenv install cdktf=0.20.7

3. Execute the cdktf script to generate Terraform:

pipenv run python main.py

4. Run Terraform on the resulting output:

terraform apply

Versions

language: Python 3.11
cdktf-cli: N/A
node: N/A
cdktf: 0.20.7
constructs: 10.3.0
jsii: 1.98.0
terraform: 1.5.7
arch: amd64
os: Debian trixie

Providers

N/A, problem occurs without any providers.

Gist

https://gist.github.com/srgoni/3f1882ad95b2587c41b1e85ac0c65809

Possible Solutions

No response

Workarounds

No response

Anything Else?

I believe that this scenario used to work with previous cdktf versions, but I don't have a reproducible setup at hand.

Full stack trace:

Traceback (most recent call last):
  File "main.py", line 2, in <module>
    from cdktf import App, TerraformStack
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/cdktf/__init__.py", line 35, in <module>
    from ._jsii import *
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/cdktf/_jsii/__init__.py", line 13, in <module>
    import constructs._jsii
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/constructs/__init__.py", line 43, in <module>
    from ._jsii import *
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/constructs/_jsii/__init__.py", line 13, in <module>
    __jsii_assembly__ = jsii.JSIIAssembly.load(
                        ^^^^^^^^^^^^^^^^^^^^^^^
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/jsii/_runtime.py", line 55, in load
    _kernel.load(assembly.name, assembly.version, os.fspath(assembly_path))
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/jsii/_kernel/__init__.py", line 299, in load
    self.provider.load(LoadRequest(name=name, version=version, tarball=tarball))
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/jsii/_kernel/providers/process.py", line 354, in load
    return self._process.send(request, LoadResponse)
           ^^^^^^^^^^^^^
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/jsii/_utils.py", line 23, in wrapped
    stored.append(fgetter(self))
                  ^^^^^^^^^^^^^
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/jsii/_kernel/providers/process.py", line 349, in _process
    process.start()
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/jsii/_kernel/providers/process.py", line 260, in start
    self._process = subprocess.Popen(
                    ^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/subprocess.py", line 1026, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/usr/lib/python3.11/subprocess.py", line 1955, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'node'
Exception ignored in: <function _NodeProcess.__del__ at 0x7fdfde7f5440>
Traceback (most recent call last):
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/jsii/_kernel/providers/process.py", line 228, in __del__
    self.stop()
  File "~/.local/share/virtualenvs/test/lib/python3.11/site-packages/jsii/_kernel/providers/process.py", line 291, in stop
    assert self._process.stdin is not None
           ^^^^^^^^^^^^^
AttributeError: '_NodeProcess' object has no attribute '_process'

References

No response

Help Wanted

• I'm interested in contributing a fix myself

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[nbaju1]

Node is a prerequisite for CDKTF whichever language you are writing in, as stated in the docs.

[srgoni]

Interesting. I assumed that the language-specific libraries were all 100% transpiled and didn't require pulling in another language ecosystem (which I'd like to avoid if possible).

It's clear that the cdktf CLI tool requires Node, but I'm not using that.

[nbaju1]

The cdktf python library utilizes the jsii library when you run app.synth(), which requires node to be available. See jsii docs.