$ pip install flask-simpleldap

from flask import Flask, g
from flask_simpleldap import LDAP

app = Flask(__name__)
#app.config['LDAP_HOST'] = 'ldap.example.org'  # defaults to localhost
app.config['LDAP_BASE_DN'] = 'OU=users,dc=example,dc=org'
app.config['LDAP_USERNAME'] = 'CN=user,OU=Users,DC=example,DC=org'
app.config['LDAP_PASSWORD'] = 'password'

ldap = LDAP(app)

@app.route('/')
@ldap.basic_auth_required
def index():
    return 'Welcome, {0}!'.format(g.ldap_username)

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

from flask import Flask, g
from flask_simpleldap import LDAP

app = Flask(__name__)

# Base
app.config['LDAP_REALM_NAME'] = 'OpenLDAP Authentication'
app.config['LDAP_HOST'] = 'openldap.example.org'
app.config['LDAP_BASE_DN'] = 'dc=users,dc=openldap,dc=org'
app.config['LDAP_USERNAME'] = 'cn=user,ou=servauth-users,dc=users,dc=openldap,dc=org'
app.config['LDAP_PASSWORD'] = 'password'

# OpenLDAP 
app.config['LDAP_OBJECTS_DN'] = 'dn'
app.config['LDAP_OPENLDAP'] = True
app.config['LDAP_USER_OBJECT_FILTER'] = '(&(objectclass=inetOrgPerson)(uid=%s))'

# Groups
app.config['LDAP_GROUP_MEMBERS_FIELD'] = "uniquemember"
app.config['LDAP_GROUP_OBJECT_FILTER'] = "(&(objectclass=groupOfUniqueNames)(cn=%s))"
app.config['LDAP_GROUP_MEMBER_FILTER'] = "(&(cn=*)(objectclass=groupOfUniqueNames)(uniquemember=%s))"
app.config['LDAP_GROUP_MEMBER_FILTER_FIELD'] = "cn"

ldap = LDAP(app)

@app.route('/')
@ldap.basic_auth_required
def index():
    return 'Welcome, {0}!'.format(g.ldap_username)

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