Generating new application with flask-server template fails

[afonsobspinto]

Running:

harness-application clockdate -t flask-server

with latest develop

returns:

WARNING:root:Overwriting file applications/clockdate/api/config.json with /home/afonso/Projects/MetaCell/cloud-harness/tools/cloudharness_utilities/application-templates/base/api/config.json
INFO:root:Merged/overridden file content of applications/clockdate/api/openapi.yaml with /home/afonso/Projects/MetaCell/cloud-harness/tools/cloudharness_utilities/application-templates/base/api/openapi.yaml
WARNING:root:Overwriting file applications/clockdate/test/api/test_st.py with /home/afonso/Projects/MetaCell/cloud-harness/tools/cloudharness_utilities/application-templates/base/test/api/test_st.py
WARNING:root:Overwriting file applications/clockdate/test/e2e/landing.spec.ts with /home/afonso/Projects/MetaCell/cloud-harness/tools/cloudharness_utilities/application-templates/base/test/e2e/landing.spec.ts
INFO:root:Merged/overridden file content of applications/clockdate/deploy/values.yaml with /home/afonso/Projects/MetaCell/cloud-harness/tools/cloudharness_utilities/application-templates/base/deploy/values.yaml
Traceback (most recent call last):
  File "/home/afonso/.pyenv/versions/ch/bin/harness-application", line 7, in <module>
    exec(compile(f.read(), __file__, 'exec'))
  File "/home/afonso/Projects/MetaCell/cloud-harness/tools/harness-application", line 73, in <module>
    generate_server(app_path)
TypeError: generate_server() missing 1 required positional argument: 'overrides_folder'

Expected:

• Generate the application stubs

[afonsobspinto]

Some relevant notes:
The problem seems to happen here: https://github.com/MetaCell/cloud-harness/blob/develop/tools/harness-application#L73
And 'overrides_folder' was added on #515

It's also unclear to me if we are suppose to support both 'server' and 'flask-server' templates.
From the harness-application help, I would say we are not:

But the truth is that when I run harness-application clockdate -t server the app is built

[aranega]

Regarding the generation without failure using server, there is a special case for it here: https://github.com/MetaCell/cloud-harness/blob/develop/tools/harness-application#L62-L66

# ...
        if template_name == 'server':
            with tempfile.TemporaryDirectory() as tmp_dirname:
                copymergedir(os.path.join(HERE, APPLICATION_TEMPLATE_PATH, template_name), tmp_dirname)
                merge_configuration_directories(app_path, tmp_dirname)
                generate_server(app_path, tmp_dirname)
#...

[filippomc]

I think we should improve the way templates are used. The double template idea seems confusing to me in general. What are the combinations which are allowed and what not?
I would go for a simpler proposal where only one template can be used by the user, leaving the possibility for the developer to compose the application with multiple templates that are implicitly included. cc @zsinnema

[zsinnema]

may be cookiecutter can be of any help https://github.com/cookiecutter/cookiecutter

imo we should not combine templates and go for application types, e.g. Django microservice, Flask microservice, React micorservice etc

[aranega]

Feature models are really good to capture configuration options: what are the "features" that are required, their mandatory dependencies, the optional ones as well as the forbidden ones. You can validate them usually to check if there is some "dead" features, and at the end, if you give some features you want for your product, you can derive the mantory other features you need to take, the optional ones you could includes and rejects the features you cannot take (or inform you that you have features that cannot work together).
I never manipulated them on a tooling point of view, perhaps it's overkill right now...

[filippomc]

I'm afraid that the complexity start exploding really soon as we are in the O(n!) and we need to control the allowed ones. It's a very powerful strategy but I don't think the trade-off will be in our favour. For our sanity we should propose to the user a set of well defined possibilities with the choice of only one, leaving the possibility to compose templates to the developer -- this is how base and server templates were conceived, but the actual implementation (the if template_name == 'server') is too ad hoc to support more templates.
I'm also open to the feature based alternative if there's a solution out there we can use.

I like @zsinnema idea to base the templating on an established library/tool.