Flask unable to read Authorization header on ElasticBeanstalk - python-3.x

Question

I have deployed a Flask app to AWS ElasticBeanstalk. The app is unable to read the 'Authorization' header in requests.
Error log reports:
KeyError: 'HTTP_AUTHORIZATION'
Error traced to:
#application.before_request
def before_request():
try:
token = request.headers['Authorization'].split(' ')[-1]
user = User.get(token=token)
g.user = user
except ValueError as e:
abort(401)
Application directory:
app/
.elasticbeanstalk
application.py
virt
.ebignore
requirements.txt
Environment configuration sets the WSGIPath to application.py:
aws:elasticbeanstalk:container:python:
NumProcesses: '1'
NumThreads: '15'
StaticFiles: /static/=static/
WSGIPath: application.py
Environment runs Python 3.6 and the following components:
Click==7.0
Flask==1.0.2
Flask-RESTful==0.3.7
itsdangerous==1.1.0
Jinja2==2.10
MarkupSafe==1.1.1
peewee==3.9.2
psycopg2==2.7.7
python-dotenv==0.10.1
pytz==2018.9
six==1.12.0
Werkzeug==0.14.1
Is anything else required?
Attempted (unsuccessful) solution:
I have burnt many hours on this, and have attempted to configure WSGIPassAuthorization, (as per advice here and elsewhere) however, I have not been successful.
Application directory containing workaround:
app/
.elasticbeanstalk
.ebextensions/
wsgi_custom.config
application.py
virt
.ebignore
requirements.txt
When I attempt to create the eb environment containing .ebextensions/wsgi_custom.config the EB CLI reports an error saying that the YAML is not valid:
ERROR: InvalidParameterValueError - The configuration file .ebextensions/wsgi_custom.config in application version app-190310_100513 contains invalid YAML or JSON. YAML exception: Invalid Yaml: while scanning a simple key
in "<reader>", line 7, column 5:
WSGIPassAuthorization On
^
could not found expected ':'
in "<reader>", line 7, column 29:
On
^
, JSON exception: Invalid JSON: Unexpected character (f) at position 0.. Update the configuration file.
Contents of .ebextensions/wsgi_custom.config:
files:
"/etc/httpd/conf.d/wsgi_custom.conf":
mode: "000644"
owner: root
group: root
content: |
WSGIPassAuthorization On
My YAML validation tool reports valid YAML.
Note: editor is set to use spaces, as per AWS YAML advice.

Answer 1

Set WSGIPassAuthorization on ElasticBeanstalk using container_commands.
Step 1. Create .ebextensions/wsgi_custom.config:
app/
.elasticbeanstalk
.ebextensions/
wsgi_custom.config
application.py
virt
.ebignore
requirements.txt
wsgi_custom.config:
container_commands:
01wsgipass:
command: 'echo "WSGIPassAuthorization On" >> ../wsgi.conf'
Step 2. Restart EB environment.
Flask app can now read 'Authorization' header in requests.

Answer 2

Solved YAML validation errors in the example above. I believe the validation errors were a red herring. The .conf file mentioned in the script now has a valid name.
Contents of .ebextensions/wsgi_custom.config:
files:
"/etc/httpd/conf.d/wsgihacks.conf":
mode: "000644"
owner: root
group: root
content: |
WSGIPassAuthorization On