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55 lines
2.1 KiB
JavaScript
55 lines
2.1 KiB
JavaScript
const logger = require('myLogger.js');
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const tokenExtractor = require('tokenExtractor.js');
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const tokenDecoder = require('tokenDecoder.js');
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exports.handler = async (event, context, callback) => {
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//1) Get the body of the event and parse it.
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const jsonBody = JSON.parse(event.body);
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/*2) Get the token. Hasura encodes all forwarded headers in a key called "headers". We passed the encoded JWT from our application in this form.
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Authorization: Bearer <JWT>
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*/
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const token = jsonBody.headers.Authorization;
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//3) Since our token start with "Bearer " clean that out.
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const cleanedToken = tokenExtractor.cleanOutBearer(token);
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logger("Cleaned Token", cleanedToken);
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//4) Decode the token so we have the claims in a dictionary.
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const claims = await tokenDecoder.decode(cleanedToken);
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/*
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At this point the flow becomes kind of custom. I'm expecting an "email" claim in my Token as I force users of my app to sign up with an email.
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I also save a user record in my PostgreSQL DB on the Cognito Pre Sign Up trigger
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https://docs.aws.amazon.com/cognito/latest/developerguide/user-pool-lambda-pre-sign-up.html
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I save the email as a unique key on the user record. I used this blog post to account for some edge cases
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https://hashrocket.com/blog/posts/working-with-email-addresses-in-postgresql
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This means that I can use the email parsed out of the claims to look up my user in my DB and then create headers based on my query('s).
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Another option would be to use the Pre Sign Up trigger to write the user to your DB and then save the new users 'id' as a custom attribute in Cognito. I think Cognito forwards custom attributes in the claim.
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*/
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//5) Get the email
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const email = claims.email;
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//6) Do what ever you need to, to get the users roles so that you can send them back as headers to Hasura.
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logger("Decoded Email", email);
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const body = {
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'X-Hasura-Role': 'user', // result.role
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'X-Hasura-User-Email': email // result.user_id
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};
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const response = {
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statusCode: 200,
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body: JSON.stringify(body),
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};
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return response;
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}; |