Slack Developer Kit for Python
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Tokens & Authentication

Tokens & Authentication

Handling tokens and other sensitive data

Slack tokens are the keys to your—or your customers’—teams. Keep them secret. Keep them safe. One way to do that is to never explicitly hardcode them.

Try to avoid this when possible:

token = 'xoxb-abc-1232'

If you commit this code to GitHub, the world gains access to this token’s team. Rather, we recommend you pass tokens in as environment variables, or persist them in a database that is accessed at runtime. You can add a token to the environment by starting your app as:

SLACK_BOT_TOKEN="xoxb-abc-1232" python myapp.py

Then in your code retrieve the key with:

import os
SLACK_BOT_TOKEN = os.environ["SLACK_BOT_TOKEN"]

You can use the same technique for other kinds of sensitive data that ne’er-do-wells could use in nefarious ways, including

  • Incoming webhook URLs
  • Slash command verification tokens
  • App client ids and client secrets

For additional information, please see our Safely Storing Credentials page.

Test Tokens

During development (prior to implementing OAuth) you can use a test token provided by the Test Token Generator. These tokens provide access to your private data and that of your team.

Tester tokens are not intended to replace OAuth 2.0 tokens. Once your app is ready for users, replace this token with a proper OAuth token implementation.

Never share test tokens with other users or applications. Do not publish test tokens in public code repositories.

The OAuth flow

Authentication for Slack’s APIs is done using OAuth, so you’ll want to read up on OAuth.

In order to implement OAuth in your app, you will need to include a web server. In this example, we’ll use Flask.

As mentioned above, we’re setting the app tokens and other configs in environment variables and pulling them into global variables.

Depending on what actions your app will need to perform, you’ll need different OAuth permission scopes. Review the available scopes here.

import os
from flask import Flask, request
from slackclient import SlackClient

client_id = os.environ["SLACK_CLIENT_ID"]
client_secret = os.environ["SLACK_CLIENT_SECRET"]
oauth_scope = os.environ["SLACK_BOT_SCOPE"]

app = Flask(__name__)

The OAuth initiation link:

To begin the OAuth flow, you’ll need to provide the user with a link to Slack’s OAuth page, This directs the user to Slack’s OAuth acceptance page, where the user will review and accept or refuse the permissions your app is requesting as defined by the requested scope(s).

For the best user experience, use the Add to Slack button to direct users to approve your application for access or Sign in with Slack to log users in.

@app.route("/begin_auth", methods=["GET"])
def pre_install():
  return '''
      <a href="https://slack.com/oauth/authorize?scope={0}&client_id={1}">
          Add to Slack
      </a>
  '''.format(oauth_scope, client_id)

The OAuth completion page

Once the user has agreed to the permissions you’ve requested on Slack’s OAuth page, Slack will redirect the user to your auth completion page. Included in this redirect is a code query string param which you’ll use to request access tokens from the oauth.access endpoint.

Generally, Web API requests require a valid OAuth token, but there are a few endpoints which do not require a token. oauth.access is one example of this. Since this is the endpoint you’ll use to retrieve the tokens for later API requests, an empty string "" is acceptable for this request.

@app.route("/finish_auth", methods=["GET", "POST"])
def post_install():

  # Retrieve the auth code from the request params
  auth_code = request.args['code']

  # An empty string is a valid token for this request
  sc = SlackClient("")

  # Request the auth tokens from Slack
  auth_response = sc.api_call(
    "oauth.access",
    client_id=client_id,
    client_secret=client_secret,
    code=auth_code
  )

A successful request to oauth.access will yield two tokens: A user token and a bot token. The user token auth_response['access_token'] is used to make requests on behalf of the authorizing user and the bot token auth_response['bot']['bot_access_token'] is for making requests on behalf of your app’s bot user.

If your Slack app includes a bot user, upon approval the JSON response will contain an additional node containing an access token to be specifically used for your bot user, within the context of the approving team.

When you use Web API methods on behalf of your bot user, you should use this bot user access token instead of the top-level access token granted to your application.

# Save the bot token to an environmental variable or to your data store
# for later use
os.environ["SLACK_USER_TOKEN"] = auth_response['access_token']
os.environ["SLACK_BOT_TOKEN"] = auth_response['bot']['bot_access_token']

# Don't forget to let the user know that auth has succeeded!
return "Auth complete!"

Once your user has completed the OAuth flow, you’ll be able to use the provided tokens to make a variety of Web API calls on behalf of the user and your app’s bot user.

See the Web API usage section of this documentation for usage examples.