ValueError: virtualenv: cannot access lib: No such virtualenv or site

[Craig Dsouza]

Hi there,

I'm new to GCP so I've had very limited success trying to debug this. 

I have a flask app which I developed using a similar process to the one described in the docs here

https://cloud.google.com/appengine/docs/standard/python/getting-started/python-standard-env

It runs well on my local machine, tested it out with dev_appserver.py 

Tried deploying it to App Engine using the Cloud SDK and the deployment is successful but the app itself shows this message

Error: Server Error
The server encountered an error and could not complete your request.
Please try again in 30 seconds.

When I check out 'Error Reporting' in the console I see the following message

 ValueError: virtualenv: cannot access /base/data/home/apps/j~project-name/20180626t222233.410714851322767617/lib: No such virtualenv or site 

I looked into StackOverflow and it appears the error is coming from this file, google.appengine.ext.vendor

Source code here: 

https://cloud.google.com/appengine/docs/standard/python/refdocs/modules/google/appengine/ext/vendor

but I'm clueless regarding how to troubleshoot this.

tried the suggestions given here, 

https://stackoverflow.com/questions/44807207/virtualenv-cannot-access-lib-no-such-virtualenv-or-site-directory

changed the appengine_config.py file and redeployed, but I'm still getting the same error 

any tips on how to debug this, i'm not even sure which 'lib' folder the error is referring to

[Craig Dsouza]

After a little more reading I'm wondering whether its my project file structure that is the issue

it is something like

-- project folder

    -- venv (python virtual environment)

       -- Include

       -- Lib

       -- Scripts

       -- tcl

       -- static (html,css,js)

       -- templates (jinja templates)

       app.yaml

       appengine_config.py

       main.py

       requirements.txt

does this seem right?

Best

Craig

[George (Cloud Platform Support)]

In fact, the project structure indicated on the "Getting Started with Flask on App Engine Standard Environment" page is: 

flask-app project structure

app.yaml: Configure the settings of your App Engine application

main.py: Write the content of your application

static: Directory to store your static files

style.css: Basic stylesheet that formats the look and feel of your template files

templates: Directory for all of your HTML templates

form.html: HTML template to display your form

submitted_form.html: HTML template to display the content of a submitted form

How does your app.yaml look like? In particular, what stays written under the "handlers" entry? It may be worthwhile having a look at "Creating a request handler for your Flask app" sub-chapter.