♻️ update settings api server

[pcrespov]

What do these changes do?

• ♻️ refactors api-server to use settings-library (based on pattern presented in http://github.com/pcrespov/sample-app-settings)
• ♻️ formatted meta constants to uppercase in both api-server and director-v2
• ✨adds CLI command to resolve and print envfiles
• 🐛added a retry policy to retrieve index from static web server since i noticed that unhandled exception shut down the web-server in one of the tests:

   aiohttp.client_exceptions.ClientConnectorError: Cannot connect to host static-webserver:8000 ssl:default [Name or service not known]

Related issue/s

• Follows from PR ✨Adding tracing in fastapi-based services (⚠️ devops) #2558

How to test

• all tests in api-server
• check CLI to produce e.g. envfiles

$ cd services/api-server
$ make install-dev
$ simcore-service-api-server --help   
...
$ simcore-service-api-server settings --help
...
$ export $(grep -v '^#' .env-devel | xargs),  simcore-service-api-server settings --compact

Checklist

check and update settings in

• core/settings.py
• .env-dev
• docker-compose

[codecov]

Codecov Report

Merging #2563 (4a91877) into master (b445b74) will decrease coverage by 0.0%.
The diff coverage is 75.7%.

@@           Coverage Diff            @@
##           master   #2563     +/-   ##
========================================
- Coverage    76.9%   76.8%   -0.1%     
========================================
  Files         622     623      +1     
  Lines       24028   24048     +20     
  Branches     2355    2356      +1     
========================================
- Hits        18483   18479      -4     
- Misses       4918    4939     +21     
- Partials      627     630      +3     

Flag	Coverage Δ
integrationtests	65.4% <70.0%> (-0.1%)	⬇️
unittests	71.3% <75.7%> (-0.1%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...s/api-server/src/simcore_service_api_server/cli.py	0.0% <0.0%> (ø)
.../simcore_service_api_server/modules/director_v2.py	46.3% <ø> (ø)
...ces/web/server/src/simcore_service_webserver/db.py	60.8% <0.0%> (-0.9%)	⬇️
...c/simcore_service_webserver/scicrunch/_resolver.py	92.3% <ø> (-3.9%)	⬇️
...e_service_api_server/api/dependencies/webserver.py	53.5% <16.6%> (-4.2%)	⬇️
...eb/server/src/simcore_service_webserver/statics.py	41.7% <46.1%> (+2.0%)	⬆️
...rver/src/simcore_service_api_server/core/events.py	83.3% <50.0%> (ø)
...simcore_service_api_server/modules/remote_debug.py	50.0% <50.0%> (ø)
...src/simcore_service_api_server/core/application.py	90.9% <73.3%> (+0.1%)	⬆️
...irector-v2/src/simcore_service_director_v2/meta.py	76.4% <75.0%> (+1.4%)	⬆️
... and 21 more

[sanderegg]

great. thanks for the changes!