launches a flask server on gcp appengine

extends https://github.com/GoogleCloudPlatform/python-docs-samples/tree/master/appengine/standard/flask/hello_world

App

main.py:

• flask app

views folder:

• route bindings in respective modules

Manifest

app.yaml:

• handlers section contains endpoint to script (wsgi or cgi) bindings
• libraries section contains standard env extension, i.e. flask lib

see https://cloud.google.com/appengine/docs/standard/python/config/appref for app manifest
see https://cloud.google.com/appengine/docs/standard/python/configuration-files for queue, cron and other manifests

Deploy/Update

git clone https://github.com/redvg/flask-on-appengine 
cd flask-on-appengine
gcloud app deploy app.yaml
gcloud app versions list
gcloud app services list

visible on http://project-id.appspot.com
update creates new version

Test

dev_appserver.py ./

open 'web preview'
change or git pull in anoher terminal, development server will detect changes automatically

Tear down resources

gcp does not support removing the app engine. current solution is to stop the app, disable it and set usage quota to 0.
this will leave the latest version artifact though. to completely remove it the only solution is to delete the project \

stopping the app: current manifest has autoscaling ON by def, which would yield
ERROR: (gcloud.app.versions.stop) INVALID_ARGUMENT: serving status cannot be changed for Automatic Scaling versions

to be able to stop alter the manifest for manual scaling

manual_scaling:
  instances: 1

see https://cloud.google.com/appengine/docs/standard/python/config/appref#scaling_elements \

then update and stop

git pull
gcloud app deploy
gcloud app versions list
gcloud app versions stop

Smth with React

shows how an entry point to react app can be served from flask \

• /react renders index.html which passes control over to react
• react prod build is altered to meet the flask structure
• app.yaml is altered to serve static content

- url: /static
  static_dir: static
  application_readable: true #NB double check is needed for prod

this still leaves serviceworker off though

some proper alternatives depending on the architecture:
.serve index.html from home route
.serve index.html from cdn (cloudstorage+firebase)
.spin up node js appengine, for py api spin up another appengine on flask

for guidance see
https://github.com/redvg/react_burger#deployment https://medium.com/tech-tajawal/deploying-react-app-to-google-app-engine-a6ea0d5af132 https://mhaligowski.github.io/blog/2017/04/05/template-for-react-application.html