Modules don't provide interpolation

[rgreinho]

I am trying to use the output of a Terraform module, and inject them into resources.

However, referring to a module object fails with the following error:

$ terraformpy
terraformpy - Processing: main.tf.py
Traceback (most recent call last):
  File "/private/tmp/terraformpy-bug/.venv/bin/terraformpy", line 10, in <module>
    sys.exit(main())
  File "/private/tmp/terraformpy-bug/.venv/lib/python3.8/site-packages/terraformpy/cli.py", line 41, in main
    imp.load_source(filename[:-6], filename)
  File "/usr/local/Cellar/python@3.8/3.8.2/Frameworks/Python.framework/Versions/3.8/lib/python3.8/imp.py", line 171, in load_source
    module = _load(spec)
  File "<frozen importlib._bootstrap>", line 702, in _load
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "main.tf.py", line 19, in <module>
    tags=[vpc.private],
  File "/private/tmp/terraformpy-bug/.venv/lib/python3.8/site-packages/terraformpy/objects.py", line 292, in __getattr__
    raise AttributeError(
AttributeError: Modules does not provide attribute interpolation through attribute access!

Context

Using python3 on OSX:

$ python3 --version
Python 3.8.2
$ system_profiler SPSoftwareDataType|grep macOS | xargs
System Version: macOS 10.15.4 (19E287)
$ pip list | grep -i terraformpy
terraformpy 1.3.0

Repro steps

The script:

from terraformpy import Module
from terraformpy import Resource


vpc = Module(
    "vpc",
    source="gruntwork-io/network/google//modules/vpc-network",
    version="0.4.0",
    project="vpc-demo",
    region="us-central1",
)
Resource(
    "google_compute_instance",
    "private",
    project="vpc-demo",
    name="vpc-private",
    machine_type="n1-standard-1",
    allow_stopping_for_update=True,
    tags=[vpc.private],
    boot_disk=dict(initialize_params=dict(image="debian-cloud/debian-9")),
    network_interface=dict(subnetwork=vpc.private_subnetwork,),
)

The steps:

mkdir -p /tmp/terraformpy-bug
cd /tmp/terraformpy-bug
pbpaste > main.tf.py
python3 -m venv .venv
source .venv/bin/activate
pip install terraformpy
terraformpy

Workaround

The workaround I am using is to manually interpolate the module reference:

network_interface=dict(subnetwork="${vpc.private_subnetwork})

But that defeats the purpose of using a python object.

@rgreinho did you ever find a solution for this? running into the same error