app.py

from flask import Flask, render_template_string, jsonify
from flask.ext.login import LoginManager, UserMixin, current_user

class User(UserMixin):
    def __init__(self, token, email):
        self.id = email
        self.token = token

USERS = {'1': User('1', 'kageurufu@kageurufu.net'),
         '2': User('2', 'TenserTensor@gmail.com'),
         '3': User('3', 'foo@bar.com')}

app = Flask(__name__)
login = LoginManager(app)
app.config['AUTH_HEADER_NAME'] = 'X-Api-Key'

@login.header_loader
def get_user(header):
    return USERS.get(header.strip(), None)

@app.route('/')
def index():
    if current_user.is_authenticated:
        return jsonify(user=current_user.get_id())
    return jsonify({'users': [dict(id=user.get_id(), token=user.token) for user in USERS.values()]})

if __name__ == '__main__':
    app.run()