Python API

Sample Project

Download a sample project specific to this tutorial configured with your Auth0 API Keys.

System Requirements
  • flask 0.11.1
  • python-jose 1.3.2
  • flask-cors 3.0.2
  • six 1.10.0
Show requirements

At some point, your APIs may need to allow limited access to users, servers, or servers on behalf of users. This tutorial demonstrates how to use the OAuth 2.0 authorization features of Auth0 to give your applications (or third-party applications) limited access to your APIs on behalf of users. For more information, check out our documentation.

Create a Resource Server (API)

In the APIs section of the Auth0 Dashboard, click the Create API button. Provide a Name and Identifier for your API. The identifier you set will later be used as the audience when configuring access_token verification. Be sure to choose the RS256 signing algorithm.

Create API

Add API Authorization

To restrict access to the resources served by your API, a check needs to be made to determine whether the incoming request contains valid authorization information. There are various methods for including authorization information in a request, but for integration with Auth0, your API needs to check for a valid JSON Web Token (JWT). When users log into your application, they will receive an id_token and an access_token which are both JWTs. The specific JWT that needs to be sent to your API is the access_token.

Install the Dependencies

This quickstart demonstrates how to add authorization to your Python API using Flask. Add the following dependencies to your requirements.txt:

flask
python-jose
flask-cors
six

Create the Flask APP

Create a server.py file and initializate the Flask App. Set the domain, audience and the error handling.

import json
from six.moves.urllib.request import urlopen
from functools import wraps

from flask import Flask, request, jsonify, _app_ctx_stack
from flask_cors import cross_origin
from jose import jwt

AUTH0_DOMAIN = 'YOUR_AUTH0_DOMAIN'
API_AUDIENCE = YOUR_API_AUDIENCE
ALGORITHMS = ["RS256"]

APP = Flask(__name__)

# Error handler
class AuthError(Exception):
    def __init__(self, error, status_code):
        self.error = error
        self.status_code = status_code
    
@APP.errorhandler(AuthError)
def handle_auth_error(ex):
    response = jsonify(ex.error)
    response.status_code = ex.status_code
    return response

Create the JWT Validation Decorator

By default, your API will be set up to use RS256 as the algorithm for signing tokens. Since RS256 works by using a private/public keypair, tokens can be verified against the public key for your Auth0 account. This public key is accessible at https://YOUR_AUTH0_DOMAIN/.well-known/jwks.json.

Add a decorator which verifies the access_token against your JWKS.

# Format error response and append status code
    
def get_token_auth_header():
    """Obtains the access token from the Authorization Header
    """
    auth = request.headers.get("Authorization", None)
    if not auth:
        raise AuthError({"code": "authorization_header_missing",
                        "description":
                            "Authorization header is expected"}, 401)
    
    parts = auth.split()
    
    if parts[0].lower() != "bearer":
        raise AuthError({"code": "invalid_header",
                        "description":
                            "Authorization header must start with"
                            " Bearer"}, 401)
    elif len(parts) == 1:
        raise AuthError({"code": "invalid_header",
                        "description": "Token not found"}, 401)
    elif len(parts) > 2:
        raise AuthError({"code": "invalid_header",
                        "description":
                            "Authorization header must be"
                            " Bearer token"}, 401)

    token = parts[1]
    return token

def requires_auth(f):
    """Determines if the access token is valid
    """
    @wraps(f)
    def decorated(*args, **kwargs):
        token = get_token_auth_header()
        jsonurl = urlopen("https://"+AUTH0_DOMAIN+"/.well-known/jwks.json")
        jwks = json.loads(jsonurl.read())
        unverified_header = jwt.get_unverified_header(token)
        rsa_key = {}
        for key in jwks["keys"]:
            if key["kid"] == unverified_header["kid"]:
                rsa_key = {
                    "kty": key["kty"],
                    "kid": key["kid"],
                    "use": key["use"],
                    "n": key["n"],
                    "e": key["e"]
                }
        if rsa_key:
            try:
                payload = jwt.decode(
                    token,
                    rsa_key,
                    algorithms=ALGORITHMS,
                    audience=API_AUDIENCE,
                    issuer="https://"+AUTH0_DOMAIN+"/"
                )
            except jwt.ExpiredSignatureError:
                raise AuthError({"code": "token_expired",
                                "description": "token is expired"}, 401)
            except jwt.JWTClaimsError:
                raise AuthError({"code": "invalid_claims",
                                "description":
                                    "incorrect claims,"
                                    "please check the audience and issuer"}, 401)
            except Exception:
                raise AuthError({"code": "invalid_header",
                                "description":
                                    "Unable to parse authentication"
                                    " token."}, 400)

            _app_ctx_stack.top.current_user = payload
            return f(*args, **kwargs)
        raise AuthError({"code": "invalid_header",
                        "description": "Unable to find appropriate key"}, 400)
    return decorated

Use this Decorator in your Methods

You can now use the decorator in any routes that require authentication.

# Controllers API

# This doesn't need authentication
@app.route("/ping")
@cross_origin(headers=['Content-Type', 'Authorization'])
def ping():
    return "All good. You don't need to be authenticated to call this"

# This does need authentication
@app.route("/secured/ping")
@cross_origin(headers=['Content-Type', 'Authorization'])
@requires_auth
def securedPing():
    return "All good. You only get this message if you're authenticated"

Protect individual endpoints

Individual routes can be configured to look for a particular scope in the access_token by using the following:

def requires_scope(required_scope):
    """Determines if the required scope is present in the access token
    Args:
        required_scope (str): The scope required to access the resource
    """
    token = get_token_auth_header()
    unverified_claims = jwt.get_unverified_claims(token)
    token_scopes = unverified_claims["scope"].split()
    for token_scope in token_scopes:
        if token_scope == required_scope:
            return True
    return False

Then, establish what scopes are needed in order to access the route. In this case example:scope is used:

@APP.route("/secured/private/ping")
@cross_origin(headers=["Content-Type", "Authorization"])
@cross_origin(headers=["Access-Control-Allow-Origin", "*"])
@requires_auth
def secured_private_ping():
    """A valid access token and an appropriate scope are required to access this route
    """
    if requires_scope("example:scope"):
        return "All good. You're authenticated and the access token has the appropriate scope"
    return "You don't have access to this resource"

Make a Call to Your API

You can now make calls to your secure API by providing the access_token as an Authorization header in your requests.


curl --request GET \
  --url http://your-domain.com/api_path \
  --header 'authorization: Bearer YOUR_ACCESS_TOKEN_HERE'
var client = new RestClient("http://your-domain.com/api_path");
var request = new RestRequest(Method.GET);
request.AddHeader("authorization", "Bearer YOUR_ACCESS_TOKEN_HERE");
IRestResponse response = client.Execute(request);
package main

import (
	"fmt"
	"net/http"
	"io/ioutil"
)

func main() {

	url := "http://your-domain.com/api_path"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("authorization", "Bearer YOUR_ACCESS_TOKEN_HERE")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := ioutil.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
HttpResponse<String> response = Unirest.get("http://your-domain.com/api_path")
  .header("authorization", "Bearer YOUR_ACCESS_TOKEN_HERE")
  .asString();
var settings = {
  "async": true,
  "crossDomain": true,
  "url": "http://your-domain.com/api_path",
  "method": "GET",
  "headers": {
    "authorization": "Bearer YOUR_ACCESS_TOKEN_HERE"
  }
}

$.ajax(settings).done(function (response) {
  console.log(response);
});
var request = require("request");

var options = { method: 'GET',
  url: 'http://your-domain.com/api_path',
  headers: { authorization: 'Bearer YOUR_ACCESS_TOKEN_HERE' } };

request(options, function (error, response, body) {
  if (error) throw new Error(error);

  console.log(body);
});
#import <Foundation/Foundation.h>

NSDictionary *headers = @{ @"authorization": @"Bearer YOUR_ACCESS_TOKEN_HERE" };

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://your-domain.com/api_path"]
                                                       cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                   timeoutInterval:10.0];
[request setHTTPMethod:@"GET"];
[request setAllHTTPHeaderFields:headers];

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
                                            completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                if (error) {
                                                    NSLog(@"%@", error);
                                                } else {
                                                    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                                                    NSLog(@"%@", httpResponse);
                                                }
                                            }];
[dataTask resume];
$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => "http://your-domain.com/api_path",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => array(
    "authorization: Bearer YOUR_ACCESS_TOKEN_HERE"
  ),
));

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}
import http.client

conn = http.client.HTTPConnection("your-domain.com")

headers = { 'authorization': "Bearer YOUR_ACCESS_TOKEN_HERE" }

conn.request("GET", "/api_path", headers=headers)

res = conn.getresponse()
data = res.read()

print(data.decode("utf-8"))
require 'uri'
require 'net/http'

url = URI("http://your-domain.com/api_path")

http = Net::HTTP.new(url.host, url.port)

request = Net::HTTP::Get.new(url)
request["authorization"] = 'Bearer YOUR_ACCESS_TOKEN_HERE'

response = http.request(request)
puts response.read_body
import Foundation

let headers = ["authorization": "Bearer YOUR_ACCESS_TOKEN_HERE"]

var request = NSMutableURLRequest(URL: NSURL(string: "http://your-domain.com/api_path")!,
                                        cachePolicy: .UseProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.HTTPMethod = "GET"
request.allHTTPHeaderFields = headers

let session = NSURLSession.sharedSession()
let dataTask = session.dataTaskWithRequest(request, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    println(error)
  } else {
    let httpResponse = response as? NSHTTPURLResponse
    println(httpResponse)
  }
})

dataTask.resume()

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