Azure functions (cloud): Install cython dependent module - installation

Question

I'm trying to install/import a cython dependent module [ZigZag] into my python function on Azure functions (Linux platfrom), I'm working via Windows 8.1 (VSCode), Running Python 3.6 on both local machine and azure functions.
I tried including Cython in the requirements.txt file, this errors out during deployment (seems installation of external modules happens somewhat in parallel)
I tried creating a '.toml' file, no luck.
I also tried the idea found here Python google cloud function deployment failure - Madmom pip package still didn't work.
Finally I decided to deploy the function first (with cython included in the 'requirements.txt' file) without the zigzag module, and then in my python script use subprocess.Popen() to do a pip install zigzag and import it before the rest of the function runs.
This is where I get stuck. In my python file I have these lines included to do the above:
#function to be called in azure __init__.py file
def f....:
# check for zigzag
try:
import zigzag
except ImportError:
subprocess.Popen(["pip", "install", "ZigZag"], shell=True)
finally:
import zigzag
.
.
.
rest of the function...
This deploys successfully to azure functions, however it fails during execution with the error:
Microsoft.Azure.WebJobs.Script.Workers.Rpc.RpcException :
Result: Failure Exception: ModuleNotFoundError: No module named 'zigzag
Any idea's how to do this correctly?
NB: This issue occurs on google cloud functions as well.

Answer 1

I see this is related to https://learn.microsoft.com/en-us/answers/questions/152557/index.html
As per the thread, the latest version for ZigZag is 0.2.2 and the supported python version is 3.5: https://pypi.org/project/ZigZag/
The azure function supports 3.6 and above python version which will make it incompatible. You can try installing the latest cython using requirements.txt and it will work as expected. But when you try to install ZigZaG it tries to find the dependency of cython package (Cython==0.26.1) that is compatible with it therefor it throws the error that cython package not found.