switch from app_server to `flask run` for local development

app_server doesn't emit app logging messages from gunicorn workers, and it was nontrivial to add. also app_server seems largely abandoned, and flask run is well supported.

README.md

@@ -28,15 +28,15 @@ Now, run the tests to check that everything is set up ok:
 ```shell
 gcloud beta emulators datastore start --no-store-on-disk --consistency=1.0 --host-port=localhost:8089 < /dev/null >& /dev/null &
 python3 -m unittest discover
-kill %1
 ```
 
 Finally, run this in the repo root directory to start the web app locally:
 
 ```shell
-dev_appserver.py --log_level debug --enable_host_checking false --support_datastore_emulator --datastore_emulator_port=8089 --application=bridgy-federated app.yaml
+env GAE_ENV=localdev flask run -p 8080
 ```
 
+
 If you send a pull request, please include (or update) a test for the new functionality!
 
 If you hit an error during setup, check out the [oauth-dropins Troubleshooting/FAQ section](https://github.com/snarfed/oauth-dropins#troubleshootingfaq). For searchability, here are a handful of error messages that [have solutions there](https://github.com/snarfed/oauth-dropins#troubleshootingfaq):

app.py

@@ -3,6 +3,7 @@ import logging
 
 from flask import Flask
 from flask_caching import Cache
+import flask_gae_static
 from oauth_dropins.webutil import (
     appengine_info,
     appengine_config,
@@ -13,7 +14,7 @@ from oauth_dropins.webutil import (
 import common
 
 
-app = Flask('bridgy-fed')
+app = Flask(__name__)
 app.template_folder = './templates'
 app.config.from_mapping(
     ENV='development' if appengine_info.DEBUG else 'PRODUCTION',
@@ -24,6 +25,7 @@ app.config.from_mapping(
 app.url_map.converters['regex'] = flask_util.RegexConverter
 app.after_request(flask_util.default_modern_headers)
 app.register_error_handler(Exception, flask_util.handle_exception)
+flask_gae_static.init_app(app)
 
 # don't redirect API requests with blank path elements
 app.url_map.redirect_defaults = True

requirements.txt

@@ -2,10 +2,10 @@ git+https://github.com/snarfed/django-salmon.git#egg=django_salmon
 git+https://github.com/snarfed/httpsig.git@HTTPSignatureAuth-sign-header#egg=httpsig
 git+https://github.com/snarfed/oauth-dropins.git#egg=oauth_dropins
 git+https://github.com/snarfed/granary.git#egg=granary
-app-server~=0.7.0; python_version>="3.8"
 feedparser~=6.0.8
 flask~=2.0.2
 flask-caching~=1.10.1
+flask-gae-static
 google-cloud-logging~=2.7.0
 gunicorn~=20.1
 mf2util~=0.5.1