[PYTHON] Try slack OAuth authentication with flask (Slack API V2)

Need for OAuth authentication

When creating a slack app, if you want to install it in only one workspace, you can manually install it from the app's ** settings page **. However, if you want to install the app personally or finally ** publish it in the Slack directory, you need to install it with OAuth authentication.

I think that the mechanism of OAuth authentication of slack is the same as the general one.

Implementation by flask

Necessary information

• client_id
• client_secret

code

import os
import slack
from flask import Flask, request, make_response

client_id = os.environ["SLACK_CLIENT_ID"]
client_secret = os.environ["SLACK_CLIENT_SECRET"]
#Add the scope required by the app here.
oauth_scope = ",".join([
  "channels:history",
  "groups:history",
  "im:history",
  "mpim:history",
  "chat:write"
  ]) #os.environ["SLACK_BOT_SCOPE"]
uuids = []

app = Flask(__name__)

@app.route("/begin_auth", methods=["GET"])
def pre_install():
    """Create a link to jump to the OAuth authentication page of slack and display it."""
    from uuid import uuid4
    state_string = str(uuid4())
    uuids.append(state_string)
    return f'<a href="https://slack.com/oauth/v2/authorize?scope={ oauth_scope }&client_id={ client_id }&state={ state_string}">Add to Slack</a>'

@app.route("/finish_auth", methods=["GET", "POST"])
def post_install():
    """It is the processing of redirected access after authentication is completed."""
    auth_code = request.args['code']
    state_code = request.args['state']

    #state_401 if the codes do not match
    if not state_code in uuids:
        return make_response("", 401)
    else:
        uuids.remove(state_code)

    #To authenticate, create a client with a blank token.
    client = slack.WebClient(token="")

    #Request an authentication token.
    response = client.oauth_v2_access(
        client_id=client_id,
        client_secret=client_secret,
        code=auth_code
    )

    #Save the slack bot token in DB etc.
    SLACK_BOT_TOKEN = response['access_token']

    #Don't forget to tell your users success!
    return make_response("Authentication successful!!", 200)

app.run()

Redirect URL settings

ʻApp> Basic Information> OAuth & Permissions> Register http: // localhost: 5000 / finish_auth in Redirect URLs`.

Save with Save URLs

access

Now you are ready Start flask and go to http: // localhost: 5000 / begin_auth.

Clicking on the link will ask you to authenticate with slack.

Press Allow to move to the next screen and generate a token at that time. If the UUID4 for verification matches, remove it from the list and use the slackClient to get an access token.

I didn't write it in this code, but let's save the obtained access token for the next use.

reference

slack API Japanese document Installing with OAuth