How to authenticate API Gateway calls with Facebook? - amazon-web-services

Problem: I want to authorize my Amazon API Gateway hosted REST API users using Facebook Authentication.
My Understanding: I know Amazon Cognito can be used to authenticate users, calling as Federated Identities. Then, I saw Authenticate API Clients with Amazon Cognito Your User Pool, which authenticates for Cognito User Pool. I also found Use Amazon API Gateway Custom Authorizers, to use from custom authorization. But, I did not find to link API Gateway to authenticate using Cognito Federated Identities (i.e. Facebook here). Can we use same procedure as User Pool for Federated Identities as well or should I use as in Custom Authorizers ?
I'm a bit confused. Any help is greatly appreciated.
Thanks in Advance.

Cognito federated identities and Cognito user pools address different use cases.
With Cognito user pools, you explicitly manage the users which can access your service. This is useful when you want to limit access to your API to a fixed set of users.
With Cognito federated identities, you delegate user management to an identity provider such as Facebook, Google, or Amazon. In that case, anyone with a user identity for your chosen identity provider can access your service. This is useful when you want to make your API broadly available, but still need to associate individual identities with your API users in order to manage per-user state or resources.
To use a federated identity, you set the API Gateway method to use “AWS_IAM” authorization. You use Cognito to create a role and associate it with your Cognito identity pool. You then use the Identity and Access Management (IAM) service to grant this role permission to call your API Gateway method.

Related

How to authenticate same user in two different AWS regions?

I have two services, sitting in two separate regions on their own, that have the same authentification solution, with AWS Cognito and each of those instances has federated in their user pool, the same identity provider.
In front of the application, there is an API Gateway, that should grant access to the desired service.
The user could have the following scenario: goes to authenticate in region1, gets his token, and then the API Gateway from region1 will permit his access based on it. Can this token be used to access a service in region2?
Assuming Cognito is configured in region1, if you set the Cognito pool from region1 as authorizer for the API Gateway in region2, that should allow this API Gateway to authenticate users in Cognito. It also works cross-account.
Hopefully the docs help: https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-enable-cognito-user-pool.html

Is AWS Federated Identities necessary if the only AWS resource a user interacts with is API Gateway?

I am currently investigating the use of Federated Identities and from the many examples I have read, it seems to be a way to grant users temporary credentials to various AWS services. For my case, the API Gateway is all that the user will interact with, since the API server is the one making calls to other services like S3 and DynamoDB. I like how permissions are controlled using IAM, but I'm failing to see any other appeals of Federated Identities. User Pools itself already supports password/fb/google/etc sign in, the only downside I see with user pools is that I'll need to do the authorization manually in the API layer. Is there something else I am missing with Federated Identities? Is it worth it given my use of only API Gateways (externally).
It all depends on the way that you will secure your API Gateway endpoint.
If you secure your API using AWS IAM, you'll need a way to convert your authentication tokens in AWS IAM Roles. For that scenario you can use AWS Cognito Idp (not the User Pool) or AWS Federated Identities. The difference is: using AWS IAM Federated Identities you will need to call AWS STS AssumeRoleWithWebIdentity in your frontend code. If you use AWS Cognito Idp this is done for you. . (AWS strongly suggest that you use the Cognito Idp in that scenario)
If you secure your API using AWS Cognito User Pools you don't need to use AWS Federated Identities. You can connect API Gateway directly to AWS Cognito and the service will enforce the controls for you. In that case you'll need to have a Cognito User Pool.
You also have a choice to use Custom Authorizers. In that scenario you will implement a lambda function that will evaluate your request and decide if it is authorized or not. In the same way, you won't need federated identities.
And finally you have the API Key authorization, that you already mentioned that is not applicable to your use case.

With AWS Amplify Auth and GraphQL API, how would you have some public, and some private query/mutation calls?

Setup:
AWS Amplify API w/ GraphQL
AWS Amplify Auth w/ Cognito User Pools
Say the majority of the platform should be accessible by a logged out user. E.g. they should be able to read forum Topics, but if they want to post, they need to sign in.
I see an #auth resolver that I can use, but whenever I try to make a graphQL call to my.url.amazonawscom/graphql to fetch Topics, it says "errorType": "UnauthorizedException". I'm having trouble figuring out how a logged out user can have authorization to publicly accessible data.
AWS AppSync recently launched support for multiple authorization types on the same AppSync API. So you could for example enable cognito user pools as the authorization type on your API and add API_KEY as an additional authorization provider.
After this, you would be able to use the #aws_api_key directive to make selected fields from your schema such as for example getForumTopics be api key authenticated. API Keys are in general considered to give public access.
Also Cognito User Pools and Cognito Federated Identities are separate products. Cognito Federated Identities does indeed have an unauthenticated identity role that you can use to secure top level fields in your schema but it looks like the auth type on your API is set to Cognito User Pools.
In Cognito identity pool you need to set the policy for unauthorized users. Go to Edit Identity Pool and you can see an option where role can be set for unauthorized

App Sync - Protecting Api for non authenticated users

We're building an application using AWS App Sync, we're still in a very early stage.
Our application has a restricted area, through user sign-in, which is being managed via aws cognito users pool. And this is fine.
We're having issues on the public area which doesn't require any authentication.
How can we protect these public endpoints?
We're having some doubts about hard coding the api key (that we know can be rotated), is it a good practice (documentation page says that it isn't ideal for production)?
Is there any way to authorise the origin? (aka, any request coming from www.foobar.baz is ok)
I would suggest using Amazon Cognito Federated Identity to control authenticated and unauthenticated access to the api. In order to do use Amazon Cognito Federated Identity with AWS AppSync, you need to use AWS IAM based authorization.
For the authenticated access you can use Amazon Cognito User Pools and federated to Amazon Cognito Federated Identity and since the federated identity can also allow for unauthenticated users it will allow you to control some api's which can be made public via an IAM policy.
For more information please read the AWS IAM Section of our security guide here
Under your AppSync app's Settings menu, where you set the User Pool Configuration, there is an option to set a default action. You can change this to DENY and all unauthenticated requests will be rejected. The alternative approach is to ALLOW everything, and manually add #aws_auth directives to every query/mutation/subscription field that you care about restricting.

aws service difference between cognito user pool and federated identity

AWS provides cognito which provides the developer with sign-up and sign-in functionality including federations with OpenId compatible identity providers such as facebook, google etc.
There are two types of categories in cognito developer console. These are managing user pool and managing federated identities.
I'm just a little bit confused because both are very similar even we want to provide our client to login with their facebook account.
The cognito user pool itself provides federation and federation identity pool also provide it by authentication providers.
The question is that if I want to allow my clients to use their own facebook account for sign-in, which categories should I use? user pool or federated identities?
In addition, if I want to configure authorizer in API gateway I have to create cognito user pool but federated identity pool. Is that the main reason choosing the cognito category?
Cognito user pool:
Amazon Cognito User Pool makes it easy for developers to add sign-up
and sign-in functionality to web and mobile applications. It serves as
your own identity provider to maintain a user directory. It supports
user registration and sign-in, as well as provisioning identity tokens
for signed-in users.
Cognito Federated Identities or Identity Pool:
Cognito Identity Pool (or Cognito Federated Identities) on the other
hand is a way to authorize your users to use the various AWS services.
Say you wanted to allow a user to have access to your S3 bucket so
that they could upload a file; you could specify that while creating
an Identity Pool. And to create these levels of access, the Identity
Pool has its own concept of an identity (or user). The source of these
identities (or users) could be a Cognito User Pool or even Facebook or
Google.
Relationship between User pool and Identity pool:
The Cognito Identity Pool simply takes all the identity providers and puts them together (federates them). And with all of this it can now give your users secure access to your AWS services, regardless of where they come from.
So in summary, the Cognito User Pool stores all the users which then plugs into Cognito Identity Pool which can give the users access to AWS services.
source
You can think of user pools as sort of a directory which contains user attributes such as name, email, phone number etc. This also provides sign up, sign in capability. You can federate users into user pools. Currently you can use Facebook, Google, and SAML as identity providers for user pools.
Cognito Federated identities lets you federate users into AWS and vends AWS credentials that can be used to access the resources you allow in your policy. For Cognito Federated Identities, you also have a variety of identity providers that you can configure such as Facebook, Google, and also Cognito User Pools can be an identity provider.
What you use depends on your use case. If you don't require AWS resources for your app, probably User Pools is all you need.
I believe AWS should separate User Pool and Identity Pool, and change the names. Because mixing up different services under the same name causes confusions, and the names do not give any clue about the services.
User Pool -> AWS Authentication and Token vending service, similar to Auth0. You can use Auth0 instead of unnecessarily complicated User Pool
Identity Pool -> AWS IAM Authorization service for the authentication tokens such as Auth0 token or AWS JWT token (from User Pool)
An analogy would be:
Use Pool is an agency in your country that identifies who you are and issues a VISA (The VISA is the token which the Identity Provider provides you as a user).
Identity Pool is the border control of the foreign country called "AWS" that you visit with the VISA. They verify who you are with the VISA and authorize what you can do in there. If the border control does not recognize the VISA, you cannot do anything. If they recognize it, then they have fine grained rules defined for each VISA what actions are allowed and where.
Forget about User Pool
Better focus on Identity Pool. Because User Pool is just another Identity Provider service like MSAD, Google, Facebook, Auth0, etc. An Identity Provider authenticates and provides a token e.g. Kerberos Token for a MS AD users, or a Cognito Userpool JWT token for a AWS Cognito Userpool user. Then Identity Pool can utilize the token to authorize access to AWS resources.
AWS has been mixing up this Identity Provider/Authentication service with Identity Pool/Authorization service, besides their strange naming, hence causing massive confusions, incurring the questions.
The name "Identity Pool" does not make any sense as it has no indication on what the service does. A word must navigate thinking that leads to understanding, not confusion. AWS exactly does the opposite.
Preparation
Before jumping to what Identity Pool does/is, better to understand a few things.
AWS STS Token
Naively saying, AWS STS Token allow us to create, use, update, delete AWS resources programmatically.
AWS_ACCESS_KEY_ID
AWS_SECRET_ACCESS_KEY
AWS_SESSION_TOKEN
If you have an AWS account user, you can get AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY for the user, and then get a STS token using e.g. MFA.
IAM Role
In reality, an IAM Role defines which actions allowed on which AWS resources for a STS token. It may not allow delete but create. So it depends on the IAM Role what a STS Token allows us to do.
However, the point to note is, there is a association between an IAM Role and a STS Token you get, and someone must define the association for you.
What Identity Pool gives you
It gives a STS Token, using which you can manipulate AWS resources in an AWS account.
Situation where Identity Pool is useful
Another problem of AWS for me is their documentation does not declare This is when you need Identity Pool, but instead keep repeating the word Federation which does not point to what Identity Pool does, allow you to manipulate AWS resources with a STS Token.
If you are in the situation where:
I want to manipulate AWS resources in an AWS account, and
I do not have an AWS IAM User (or I do not want to use it), but
I have an account in Corporate AD, or in Google, or in Facebook, or in Auth0, or ..., or in Cognito User Pool.
Then you can use Identity Pool to get a STS token for the account e.g Google you logged in, and can manipulate the AWS resource.
For instance, if you have 1000+ users in your corporate AD and want to let them use AWS resources somehow. Would you create 1000+ AWS IAM users? Or find a way to map them to a few IAM roles such as "Administrator", "Accounting", "Finance", "IT"?
What Identity Pool does
Identity Pool maps an Identity Provider token (e.g. Google token) to an IAM Role in an AWS account, and gives a STS Token.
AWS calls this "mapping" as Federation, in my understanding.
I would recommend completely forgetting User Pool when discussing Identity Pool. User Pool is just another Identity Provider which you may not need at all.
Likewise, when discussing User Pool, I would recommend completely forgetting Identity Pool.
I do hope AWS will separate Identity Provider Service (User Pool) from Token Mapping service (Identity Pool) to stop causing confusions.
The best summary I have ever heard is:
user pools return JSON Web Tokens (JWTs) which are used to access APIs that you built (using api gateway or appsync)
identity pools return Security Token Service (STS) tokens that are used to access APIs that aws built (s3, dynamodb, etc.)
Watch this cognito deep dive video for more details.
The below picture is a good answer to the question (User pool Vs Identity Pool)