I'm using AWS amplify to create an app, where users can upload images using either private or public file access levels, as described in the documentation. Besides this, I've implemented a lambda function which upon request through API gateway modifies an image and returns a link to the modified image.
What I want is that a given user should be able to call the API and modify only his own images, but not that of other users; i.e. allow the AWS lambda function to use the execution role from the cognito user. If I allow the lambda function to access all data in the S3 bucket then it works fine - but I don't want users to be able to access other users images.
I've been at it for a while now, trying different things to no avail.
Now I've integrated the API with the user pool as described here:
https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-enable-cognito-user-pool.html
And then I've tried to follow this guide:
https://aws.amazon.com/premiumsupport/knowledge-center/cognito-user-pool-group/
Which does not work since the "cognito:roles" is not present in the event variable of the lambda_handler (presumably because there are not user pool groups?).
What would the right way be to go about this in an AWS Amplify app?
Primarily, I've followed this guide:
https://aws.amazon.com/premiumsupport/knowledge-center/cognito-user-pool-group/
Use API Gateway request mapping and check permissions in Lambda itself:
Use API Gateway request mapping to pass context.identity.cognitoIdentityId to Lambda. Just it should be a Lambda integration with mapping (not a Proxy integration). Another limitation is that API request should be POST, for GET it's also possible if you map cognitoIdentityId to query string.
Lambda has access to all files in S3
Implement access control check in Lambda itself. Lambda can read all permissions of the file in S3. And then see if owner is Cognito user.
Related
how can we make sure that a particular policy ( say S3 bucket access restriction policy ) is attached to all newly created Roles.
Can we write a Lambda that gets triggered only when a new Role is created and check and if missing attached required policies?
AttachRolePolicy API can be used to attach policy to a role. Are there any examples available in AWS Lambda to get this done?
Does Terraform provides any such modules readily available that can be referred in this context.
Yes, this is possible. You can configure a lambda function that's triggered by EventBridge via CloudTrail when a specific AWS API is called. Take a look at the doc here. Since this is pretty simple, I don't think there is a specific module created for this. You can write your own directly based on the resources in the AWS provider.
Python SDK for AWS Boto3, is having multiple APIs that can be used like adding a role, policy etc. It is very simple and documentation is awesome.
https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
an example to attach a policy to an existing role:
client= boto3.resource('iam')
response = client.attach_role_policy(
PolicyArn='arn:aws:iam::aws:policy/ReadOnlyAccess',
RoleName='ReadOnlyRole',
)
Similarly other clients can be grabbed for other AWS services.
So I'm completely new to lambda and S3 and I need to be able to let a client send and retrieve image uri data from S3
Anyone know where I should start?
if you want your clients , send and retrieve images and metadata about the images to s3 , you don't even lambda to do so , you can use any of AWS sdk's available for a variety of programming languages to directly interact with s3.
for e.g, I am attaching a link to example to make a photo gallery type application using s3 and javascript sdk for AWS. you can do such with any programming language for whch sdk are available
https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/s3-example-photo-album.html
Your client can directly interact with AWS S3 using AWS SDK for javascript, using this client can directly upload and retrieve data from the browser.
If you are planning to use S3 with lambda. Attach API Gateway endpoint to AWS Lambda, using this endpoint your client can make REST calls to your Lambda.
Write a Lambda function to handle GET and POST request to retrieve and send data. One Lambda function can have only one entry point, keep this in mind while writing code.
Use this lambda function to connect to S3. As you are new, keep in mind to give Lambda role permission to access S3.
I am looking for a solution on the best practice that needs to be followed in AWS S3 access by third party who do not have account in S3.
In my case there are REST interface which would need to provide the link of images .This images resides on AWS S3. Based on the identity of the caller is there a way we can give access to the user. I would not want to make the access level of the bucket to public.
Say if we get a call from user X ( may be we ask them to set a new header ) we allow them the access to the bucket.
As this API is enterprise and we have partners using this API we would want only some of the identified callers to have access to the images.
Any pointers will help a lot.
Signed S3 URL's, make the bucket private, only accessible to your API via an IAM role, if the API is running on EC2, lambda etc.
Your API would do the authentication and authorization, then provide the caller a signed s3 url to download the image.
When you create a pre-signed URL for your object, you must provide your security credentials, specify a bucket name, an object key, specify the HTTP method (GET to download the object) and expiration date and time. The pre-signed URLs are valid only for the specified duration.
Anyone who receives the pre-signed URL can then access the object. For
example, if you have a video in your bucket and both the bucket and
the object are private, you can share the video with others by
generating a pre-signed URL.
I'm using Lambda and S3 in conjunction with Amazon's Skills Kit. The Lambda is running Node.js and referencing audio files which I use SSML for playback on Alexa commands. However, since I get charged for GET requests, I'd like to limit the requests to just the servers requesting specifically from Alexa. Although I can set an IAM user to restrict access, I think I'll get an access denied response when trying to play back from Alexa. Can I restrict playback based on a known Alexa IP? It appears that the IAM information isn't passed through regular HTTP requests to S3 GETs.
Maybe you could daisy-chain lambda requests. Have one lambda function to handle the Alexa app, and if an intent involves an audio file, call another lambda function.
I have a REST API with API gateway and Lambda.
I wan't to create an endpoint for uploading a profile picture, that passes the file to a Lambda function, where it is been resized, registers it to the database and returning the url path of the new image.
Is there any way to do so with those services?
Couldn't find anything online (the only suggestion I found is uploading directly to S3, which requires IAM permissions, and having an event triggering a Lambda function that resizing the picture).
Thanks
UPDATE
AWS updated APIGATEWAY and know you can send binaries through an endpoint
Thanks to #blue and #Manzo for commenting it
Uploading a file directly to S3 doesn't necessarily require IAM permissions. You would create an API endpoint that returns a pre-signed S3 URL, which could then be used to upload the file directly to S3. The Lambda function behind the API endpoint would be the only thing that needed the correct IAM permissions for the S3 bucket.
Since API Gateway and Lambda don't support natively currently, you can pass the file to a picture in based64 encoded to API Gateway then pass to Lambda function. Your Lambda function can based64 decoded, then resized, registers it to the database and returning the url path of the new image.