Retrieve bucket objects without knowing bucket area with AWS S3 REST API

Question

I am trying to get bucket objects with the AWS S3 REST API (I do not use the SDK), but unfortunately I am facing the following problem: I do not know its region when I call the API.

That's what I'm doing:

• I am creating a request to "https: // [bucketname] .s3.amazonaws.com /"
• I sign the request using the default scope set to "us-west-1" (using the AWS4 signing process).
• But imagine that the bucket I'm trying to install is set to the us-west-2 area, AWS throws me an error.

So here is my question:

Is there a way to get a list of bucket objects without knowing its region? Or is there an easy way to get a bucket area?

INFO: I read that there are two styles for calling the bucket: "path style" and "shared hosting style", but whenever I send a request to " https://s3.amazonaws.com/ [bucketname]" instead of this he gives me a redirect error ...

Answer 1

AWS V4 authentication requires that you know the bucket area so that you can sign the request correctly. Otherwise:

HTTP/1.1 400 Bad Request <?xml version="1.0" encoding="UTF-8"?> <Error> <Code>AuthorizationHeaderMalformed</Code> <Message>The authorization header is malformed; the region 'us-east-1' is wrong; expecting 'us-west-2'</Message> <Region>us-west-2</Region> <RequestId>xxxx</RequestId> <HostId>xxxx</HostId> </Error> 

V2 signatures were not region specific, so there was previously a simple way to find out the bucket area using a V2 request:

http://docs.aws.amazon.com/AmazonS3/latest/API/RESTBucketGETlocation.html

However, there is suspicion of a trick-22 with V4, since you need to know the bucket area before you can make a call to discover the bucket area.

So the first solution is to capture the <Region> returned in the error response and use this area to sign future requests for the bucket. Obviously, you will want to cache this information, as this will not lead to reduced performance and increased costs.

Alternatively, there is a way to ask the US-Standard (us-east-1) region about the location of any bucket in any region using this URL format only :

 https://s3.amazonaws.com/bucket-name?location 

Sign this request in the us-east-1 region and you will get an answer wherever the bucket is. Note that if the bucket is in us-east-1 (US-Standard), then LocationConstraint returned empty.

 <?xml version="1.0" encoding="UTF-8"?> <LocationConstraint xmlns="http://s3.amazonaws.com/doc/2006-03-01/"> us-west-2 </LocationConstraint> 

You cannot use this URL construct to actually list bucket objects in other regions, since https://s3.amazonaws.com/ always routes your request to US-Standard (us-east-1), but you can use it to detecting the area of ​​any bucket, as US-Standard has this information.

---

Update / Additonal

At some point, S3 adds a new x-amx-bucket-region: response header, which appears to be an undocumented addition to the REST API, and appears to be added to many of the responses to S3's error, in particular 403 errors.

This seems like a useful self-correction mechanism if you get an error response.

In addition, the information above on how to poll the US-Standard region about the location of any bucket anywhere is still accurate, and the same request should work if it is sent to any regional REST endpoint of region S3, and not just to US-Standard, because all regions know the location of all the other buckets: for example, https://s3-us-west-2.amazonaws.com/bucket-name?location would ask US-West-2 (Oregon), which also has the same information as for any bucket around the world. In some cases, you may need to survey your nearest region.

Answer 2

In Ruby, you can pass the region as such when you receive the resource:

 s3 = Aws::S3::Resource.new(region: 'us-west-2') 

Answer 3

You can get the region from the exception → additional information

  AmazonS3 client = AmazonS3ClientBuilder.standard() .withCredentials(new AWSStaticCredentialsProvider(credentials)).withRegion(Regions.US_EAST_1).build(); Regions bucketRegion = Regions.US_EAST_1; try { client.getBucketLocation(bucket.getName()); } catch (AmazonS3Exception e) { bucketRegion = Regions.fromName(e.getAdditionalDetails().get("Region")); } 

This is not the best way to do this, but right now there is no alternative for this.

Answer 4

If your request simply indicates the wrong region, S3 will respond with a temporary redirect. Since you mentioned this with a constant redirect, which indicates that the request is incorrect. S3 usually responds with a helpful message inside the response body to help figure out the problem. You want to read the response body to correct the request.

Answer 5

Following @ patrice-gagnon's answer, I entered the region configuration in the AWS instance and it helped me.

By the way, I'm using Typescript in NestJS

 const s3 = new AWS.S3({ region: 'eu-west-3' });