I have been trying to reason why an S3 bucket name has to be globally unique. I came across the stackoverflow answer as well that says in order to resolve host header, bucket name got to be unique. However, my point is can't AWS direct the s3-region.amazonaws.com to region specific web server that can serve the bucket object from that region? That way the name could be globally unique only for a region. Meaning, the same bucket could be created in a different region. Please let me know if my understanding is completely wrong on how name resolution works or otherwise?
There is not, strictly speaking, a technical reason why the bucket namespace absolutely had to be global. In fact, it technically isn't quite as global as most people might assume, because S3 has three distinct partitions that are completely isolated from each other and do not share the same global bucket namespace across partition boundaries -- the partitions are aws (the global collection of regions most people know as "AWS"), aws-us-gov (US GovCloud), and aws-cn (the Beijing and Ningxia isolated regions).
So things could have been designed differently, with each region independent, but that is irrelevant now, because the global namespace is entrenched.
But why?
The specific reasons for the global namespace aren't publicly stated, but almost certainly have to do with the evolution of the service, backwards compatibility, and ease of adoption of new regions.
S3 is one of the oldest of the AWS services, older than even EC2. They almost certainly did not foresee how large it would become.
Originally, the namespace was global of necessity because there weren't multiple regions. S3 had a single logical region (called "US Standard" for a long time) that was in fact comprised of at least two physical regions, in or near us-east-1 and us-west-2. You didn't know or care which physical region each upload went to, because they replicated back and forth, transparently, and latency-based DNS resolution automatically gave you the endpoint with the lowest latency. Many users never knew this detail.
You could even explicitly override the automatic geo-routing of DNS amd upload to the east using the s3-external-1.amazonaws.com endpoint or to the west using the s3-external-2.amazonaws.com endpoint, but your object would shortly be accessible from either endpoint.
Up until this point, S3 did not offer immediate read-after-write consistency on new objects since that would be impractical in the primary/primary, circular replication environment that existed in earlier days.
Eventually, S3 launched in other AWS regions as they came online, but they designed it so that a bucket in any region could be accessed as ${bucket}.s3.amazonaws.com.
This used DNS to route the request to the correct region, based on the bucket name in the hostname, and S3 maintained the DNS mappings. *.s3.amazonaws.com was (and still is) a wildcard record that pointed everything to "S3 US Standard" but S3 would create a CNAME for your bucket that overrode the wildcard and pointed to the correct region, automatically, a few minutes after bucket creation. Until then, S3 would return a temporary HTTP redirect. This, obviously enough, requires a global bucket namespace. It still works for all but the newest regions.
But why did they do it that way? After all, at around the same time S3 also introduced endpoints in the style ${bucket}.s3-${region}.amazonaws.com ¹ that are actually wildcard DNS records: *.s3-${region}.amazonaws.com routes directly to the regional S3 endpoint for each S3 region, and is a responsive (but unusable) endpoint, even for nonexistent buckets. If you create a bucket in us-east-2 and send a request for that bucket to the eu-west-1 endpoint, S3 in eu-west-1 will throw an error, telling you that you need to send the request to us-east-2.
Also, around this time, they quietly dropped the whole east/west replication thing, and later renamed US Standard to what it really was at that point -- us-east-1. (Buttressing the "backwards compatibility" argument, s3-external-1 and s3-external-2 are still valid endpoints, but they both point to precisely the same place, in us-east-1.)
So why did the bucket namespace remain global? The only truly correct answer an outsider can give is "because that's what the decided to do."
But perhaps one factor was that AWS wanted to preserve compatibility with existing software that used ${bucket}.s3.amazonaws.com so that customers could deploy buckets in other regions without code changes. In the old days of Signature Version 2 (and earlier), the code that signed requests did not need to know the API endpoint region. Signature Version 4 requires knowledge of the endpoint region in order to generate a valid signature because the signing key is derived against the date, region, and service... but previously it wasn't like that, so you could just drop in a bucket name and client code needed no regional awareness -- or even awareness that S3 even had regions -- in order to work with a bucket in any region.
AWS is well-known for its practice of preserving backwards compatibility. They do this so consistently that occasionally some embarrassing design errors creep in and remain unfixed because to fix them would break running code.²
Another issue is virtual hosting of buckets. Back before HTTPS was accepted as non-optional, it was common to host ststic content by pointing your CNAME to the S3 endpoint. If you pointed www.example.com to S3, it would serve the content from a bucket with the exact name www.example.com. You can still do this, but it isn't useful any more since it doesn't support HTTPS. To host static S3 content with HTTPS, you use CloudFront in front of the bucket. Since CloudFront rewrites the Host header, the bucket name can be anything. You might be asking why you couldn't just point the www.example.com CNAME to the endpoint hostname of your bucket, but HTTP and DNS operate at very different layers and it simply doesn't work that way. (If you doubt this assertion, try pointing a CNAME from a domain that you control to www.google.com. You will not find that your domain serves the Google home page; instead, you'll be greeted with an error because the Google server will only see that it's received a request for www.example.com, and be oblivious to the fact that there was an intermediate CNAME pointing to it.) Virtual hosting of buckets requires either a global bucket namespace (so the Host header exactly matches the bucket) or an entirely separate mapping database of hostnames to bucket names... and why do that when you already have an established global namespace of buckets?
¹ Note that the - after s3 in these endpoints was eventually replaced by a much more logical . but these old endpoints still work.
² two examples that come to mind: (1) S3's incorrect omission of the Vary: Origin response header when a non-CORS request arrives at a CORS-enabled bucket (I have argued without success that this can be fixed without breaking anything, to no avail); (2) S3's blatantly incorrect handling of the symbol + in an object key, on the API, where the service interprets + as meaning %20 (space) so if you want a browser to download from a link to /foo+bar you have to upload it as /foo{space}bar.
You create an S3 bucket in a specific region only and objects stored in a bucket is only stored in that region itself. The data is neither replicated nor stored in different regions, unless you setup replication on a per bucket basis.
However. AWS S3 shares a global name space with all accounts. The name given to an S3 bucket should be unique
This requirement is designed to support globally unique DNS names for each bucket eg. http://bucketname.s3.amazonaws.com
Related
I have been trying to reason why an S3 bucket name has to be globally unique. I came across the stackoverflow answer as well that says in order to resolve host header, bucket name got to be unique. However, my point is can't AWS direct the s3-region.amazonaws.com to region specific web server that can serve the bucket object from that region? That way the name could be globally unique only for a region. Meaning, the same bucket could be created in a different region. Please let me know if my understanding is completely wrong on how name resolution works or otherwise?
There is not, strictly speaking, a technical reason why the bucket namespace absolutely had to be global. In fact, it technically isn't quite as global as most people might assume, because S3 has three distinct partitions that are completely isolated from each other and do not share the same global bucket namespace across partition boundaries -- the partitions are aws (the global collection of regions most people know as "AWS"), aws-us-gov (US GovCloud), and aws-cn (the Beijing and Ningxia isolated regions).
So things could have been designed differently, with each region independent, but that is irrelevant now, because the global namespace is entrenched.
But why?
The specific reasons for the global namespace aren't publicly stated, but almost certainly have to do with the evolution of the service, backwards compatibility, and ease of adoption of new regions.
S3 is one of the oldest of the AWS services, older than even EC2. They almost certainly did not foresee how large it would become.
Originally, the namespace was global of necessity because there weren't multiple regions. S3 had a single logical region (called "US Standard" for a long time) that was in fact comprised of at least two physical regions, in or near us-east-1 and us-west-2. You didn't know or care which physical region each upload went to, because they replicated back and forth, transparently, and latency-based DNS resolution automatically gave you the endpoint with the lowest latency. Many users never knew this detail.
You could even explicitly override the automatic geo-routing of DNS amd upload to the east using the s3-external-1.amazonaws.com endpoint or to the west using the s3-external-2.amazonaws.com endpoint, but your object would shortly be accessible from either endpoint.
Up until this point, S3 did not offer immediate read-after-write consistency on new objects since that would be impractical in the primary/primary, circular replication environment that existed in earlier days.
Eventually, S3 launched in other AWS regions as they came online, but they designed it so that a bucket in any region could be accessed as ${bucket}.s3.amazonaws.com.
This used DNS to route the request to the correct region, based on the bucket name in the hostname, and S3 maintained the DNS mappings. *.s3.amazonaws.com was (and still is) a wildcard record that pointed everything to "S3 US Standard" but S3 would create a CNAME for your bucket that overrode the wildcard and pointed to the correct region, automatically, a few minutes after bucket creation. Until then, S3 would return a temporary HTTP redirect. This, obviously enough, requires a global bucket namespace. It still works for all but the newest regions.
But why did they do it that way? After all, at around the same time S3 also introduced endpoints in the style ${bucket}.s3-${region}.amazonaws.com ¹ that are actually wildcard DNS records: *.s3-${region}.amazonaws.com routes directly to the regional S3 endpoint for each S3 region, and is a responsive (but unusable) endpoint, even for nonexistent buckets. If you create a bucket in us-east-2 and send a request for that bucket to the eu-west-1 endpoint, S3 in eu-west-1 will throw an error, telling you that you need to send the request to us-east-2.
Also, around this time, they quietly dropped the whole east/west replication thing, and later renamed US Standard to what it really was at that point -- us-east-1. (Buttressing the "backwards compatibility" argument, s3-external-1 and s3-external-2 are still valid endpoints, but they both point to precisely the same place, in us-east-1.)
So why did the bucket namespace remain global? The only truly correct answer an outsider can give is "because that's what the decided to do."
But perhaps one factor was that AWS wanted to preserve compatibility with existing software that used ${bucket}.s3.amazonaws.com so that customers could deploy buckets in other regions without code changes. In the old days of Signature Version 2 (and earlier), the code that signed requests did not need to know the API endpoint region. Signature Version 4 requires knowledge of the endpoint region in order to generate a valid signature because the signing key is derived against the date, region, and service... but previously it wasn't like that, so you could just drop in a bucket name and client code needed no regional awareness -- or even awareness that S3 even had regions -- in order to work with a bucket in any region.
AWS is well-known for its practice of preserving backwards compatibility. They do this so consistently that occasionally some embarrassing design errors creep in and remain unfixed because to fix them would break running code.²
Another issue is virtual hosting of buckets. Back before HTTPS was accepted as non-optional, it was common to host ststic content by pointing your CNAME to the S3 endpoint. If you pointed www.example.com to S3, it would serve the content from a bucket with the exact name www.example.com. You can still do this, but it isn't useful any more since it doesn't support HTTPS. To host static S3 content with HTTPS, you use CloudFront in front of the bucket. Since CloudFront rewrites the Host header, the bucket name can be anything. You might be asking why you couldn't just point the www.example.com CNAME to the endpoint hostname of your bucket, but HTTP and DNS operate at very different layers and it simply doesn't work that way. (If you doubt this assertion, try pointing a CNAME from a domain that you control to www.google.com. You will not find that your domain serves the Google home page; instead, you'll be greeted with an error because the Google server will only see that it's received a request for www.example.com, and be oblivious to the fact that there was an intermediate CNAME pointing to it.) Virtual hosting of buckets requires either a global bucket namespace (so the Host header exactly matches the bucket) or an entirely separate mapping database of hostnames to bucket names... and why do that when you already have an established global namespace of buckets?
¹ Note that the - after s3 in these endpoints was eventually replaced by a much more logical . but these old endpoints still work.
² two examples that come to mind: (1) S3's incorrect omission of the Vary: Origin response header when a non-CORS request arrives at a CORS-enabled bucket (I have argued without success that this can be fixed without breaking anything, to no avail); (2) S3's blatantly incorrect handling of the symbol + in an object key, on the API, where the service interprets + as meaning %20 (space) so if you want a browser to download from a link to /foo+bar you have to upload it as /foo{space}bar.
You create an S3 bucket in a specific region only and objects stored in a bucket is only stored in that region itself. The data is neither replicated nor stored in different regions, unless you setup replication on a per bucket basis.
However. AWS S3 shares a global name space with all accounts. The name given to an S3 bucket should be unique
This requirement is designed to support globally unique DNS names for each bucket eg. http://bucketname.s3.amazonaws.com
I found out Amazon S3 give me different IP address when I tried to access the same resources. 13.111.11.11 and 13.222.11.11. Do they point to the same server location or do they point to different server location. If a file get updated, does accessing it on the two different IP make a difference in terms if we want to get it first?
You should always access Amazon S3 by using the provided DNS name (eg my-bucket.s3-us-west-2.amazonaws.com).
There are many, many servers powering Amazon S3 so you should never cache nor use a particular IP address. Also, if you are using a DNS name that resolves to a particular bucket (like the example above), S3 requires the domain name to know which bucket to access (since an IP address alone is insufficient).
The Amazon S3 Data Consistency Model says:
Amazon S3 provides read-after-write consistency for PUTS of new objects in your S3 bucket in all regions ... Amazon S3 offers eventual consistency for overwrite PUTS and DELETES in all regions.
So, new files will always return the file, but updates might be subject to a short delay as the change is propagated between servers.
I have following S3 buckets
"client1"
"client2"
...
"clientX"
and our clients upload data to their buckets via jar app (client1 to bucket client1 ect.). Here is peace of code:
BasicAWSCredentials credentials = new BasicAWSCredentials(accessKey, secretKey);
AmazonS3 s3client = new AmazonS3Client(credentials);
s3client.setRegion(Region.getRegion(Regions.US_EAST_1));
File file = new File(OUTPUT_DIRECTORY + '/' + fileName);
s3client.putObject(new PutObjectRequest(bucketName, datasource + '/' + fileName, file));
and problem is, that they have firewall for output traffic. They must allow URL .amazonaws.com in firewall. Is it possible to set endpoint to our domain storage.domain.com ?
We are expecting, that we will change region in future, but all our client are locket to amazonaws.com = US_EAST_1 region now -> all our clients will need change rules in firewall.
If the endpoint will be storage.domain.com - everything will be ok :)
Example of expected clients URL
client1 will put data to URL client1.storage.domain.com
client2 will put data to URL client2.storage.domain.com
clientX will put data to URL clientX.storage.domain.com
We know about setting in CloudFront, but it's per bucket. We are finding solution with one global AWS setting. How can we do that?
Thank you very much
Not sure if this will be affordable for you (due to extra fee you may have), but this should work:
Create Route53 with your domain and subdomains (client1, client2.. clientX)
Create (or use default) VPC with endpoints (https://aws.amazon.com/blogs/aws/new-vpc-endpoint-for-amazon-s3/)
Route all traffic from Route53 to your VPC through the internet gateway (IGW)
You may need to have Security group and NACL things configured. Let me know if you need further details.
There are numerous factors at play, here, not the least of which is support for SSL.
First, we need to eliminate one obvious option that will not work:
S3 supports naming each bucket after a domain name, then using a CNAME to point at each bucket. So, for example, if you name a bucket client-1.storage.example.com and then point a DNS CNAME (in Route 53) for client-1.storage.example.com CNAME client-1.storage.example.com.s3.amazonaws.com then this bucket becomes accessible on the Internet as client-1.storage.example.com.
This works only if you do not try to use HTTPS. The reason for the limitation is a combination of factors, which are outside the scope of this answer. There is no workaround that uses only S3. Workarounds require additonal components.
Even though the scenario above will not work for your application, let's assume for a moment that it will, since it makes another problem easy to illustrate:
We are finding solution with one global AWS setting
This may not be a good idea, even if it is possible. In the above scenario, it would be tempting for you to set up a wildcard CNAME so that *.storage.example.com CNAME s3[-region].amazonaws.com which would give you a magical DNS entry that would work for any bucket with a name matching *.storage.example.com and created in the appropriate region... but there is a serious vulnerability in such a configuration -- I could create a bucket called sqlbot.storage.example.com (assuming no such bucket already existed) and now I have a bucket that you do not control, using a hostname under your domain, and you don't have any way to know about it, or stop it. I can potentially use this to breach your clients' security because now my bucket is accessible from inside your client's firewall, thanks to the wildcard configuration.
No, you really need to automate the steps to deploy each client, regardless of the ultimate solution, rather than relying on a single global setting. All AWS services (S3, Route 53, etc.) lend themselves to automation.
CloudFront seems like it holds the key to the simplest solution, by allowing you to map each client hostname to their own bucket. Yes, this does require a CloudFront distribution to be configured for each client, but this operation can also be automated, and there isn't a charge for each CloudFront distribution. The only charges for CloudFront are usage-related (per request and per GB transferted). Additional advantages here include SSL support (including wildcard *.storage.example.com certificate from ACM which can be shared across multiple CloudFront distributions) and the fact that with CloudFront in the path, you do not need the bucket name and the hostname to be the same.
This also gives you the advantage of being able to place each bucket in the most desirable region for that specific bucket. It is, however, limited to files not exceeding 20 GB in size, due to the size limit imposed by CloudFront.
But the problem with using CloudFront for applications with a large number of uploads of course is that you're going to pay bandwidth charges for the uploads. In Europe, Canada, and the US, it's cheap ($0.02/GB) but in India it is much more expensive ($0.16/GB), with other areas varying in price between these extremes. (You pay for downloads with CloudFront, too, but in that case, S3 does not bill you for any bandwidth charges when downloads are pulled through CloudFront... so the consideration is not usually as significant, and adding CloudFront in front of S3 for downloads can actually be slightly cheaper than using S3 alone).
So, while CloudFront is probably the official answer, there are a couple of considerations that are still potentially problematic.
S3 transfer acceleration avoids the other problem you mentioned -- the bucket regions. Buckets with transfer acceleration enabled are accessible at https://bucket-name.s3-accelerate.amazonaws.com regardless of the bucket region, so that's a smaller hole to open, but the transfer acceleration feature is only supported for buckets without dots in their bucket names. And transfer acceleration comes with additional bandwidth charges.
So where does this leave you?
There's not a built-in, "serverless" solution that I can see that would be simple, global, automatic, and inexpensive.
It seems unlikely, in my experience, that a client who is so security-conscious as to restrict web access by domain would simultaneously be willing to whitelist what is in effect a wildcard (*.storage.example.com) and could result in trusting traffic that should not be trusted. Granted, it would be better than *.amazonaws.com but it's not clear just how much better.
I'm also reasonably confident that many security configurations rely on static IP address whitelisting, rather than whitelisting by name... filtering by name in an HTTPS environment has implications and complications of its own.
Faced with such a scenario, my solution would revolve around proxy servers deployed in EC2 -- in the same region as the buckets -- which would translate the hostnames in the requests into bucket names and forward the requests to S3. These could be deployed behind ELB or could be deployed on Elastic IP addresses, load balanced using DNS from Route 53, so that you have static endpoint IP addresses for clients that need them.
Note also that any scenario involving Host: header rewrites for requests authorized by AWS Signature V4 will mean that you have to modify your application's code to sign the requests with the real hostname of the target S3 endpoint, while sending the requests to a different hostname. Sending requests directly to the bucket endpoint (including the transfer acceleration endpoint) is the only way to avoid this.
OK, so I have a an Amazon S3 bucket to which I want to allow users to upload files directly from the client over https.
In order to do this it became apparent that I would have to change the bucket name from a format using periods to a format using dashes. So :
my.bucket.com
became :
my-bucket-com
This being required due to a limitation of https authentication which can't deal with periods in the bucket name when resolving the S3 endpoint.
So everything is peachy, except now I'd like to allow access to those files while hiding the fact that they are being stored on Amazon S3.
The obvious choice seems to be to use Route 53 zone configuration records to add a CNAME record to point my url at the bucket, given that I already have the 'bucket.com' domain :
my.bucket.com > CNAME > my-bucket-com.s3.amazonaws.com
However, I now seem to have hit another limitation, in that Amazon seem to insist that the name of the CNAME record must match the bucket name exactly so the above example will not work.
My temporary solution is to use a reverse proxy on an EC2 instance while traffic volumes are low. But this is not a good or long term solution as it means that all S3 access is being funneled through the proxy server causing extra server load, and data transfer charges. Not to mention the solution really isn't scalable when traffic volumes start to increase.
So is it possible to achieve both of my goals above or are they mutually exclusive?
If I want to be able to upload directly from clients over https, I can't then hide the S3 url from end users accessing that content and vice versa?
Well there simply doesn't seem to be a straightforward way of achieving this.
There are 2 possible solutions :
1.) Put your S3 bucket behind Amazon Cloudfront - but this does incur a lot more charges, all be it with the added benefit of lower latency regional access to your content.
2.) The solution we will go with will simply be to split the bucket in to two.
One for upload from HTTPS clients my-bucket-com; And one for CNAME aliased access to that content my.bucket.com. This keeps the costs down, although it will involve extra steps in organising the content before it can be accessed.
Background
We use Amazon S3 in our project as a storage for files uploaded by clients.
For technical reasons, we upload a file to S3 with a temporary name, then process its contents and rename the file after it has been processed.
Problem
The 'rename' operation fails time after time with 404 (key not found) error, although the file being renamed had been uploaded successfully.
Amazon docs mention this problem:
Amazon S3 achieves high availability by replicating data across multiple servers within Amazon's data centers.
If a PUT request is successful, your data is safely stored. However, information about the changes must replicate across Amazon S3, which can take some time, and so you might observe the following behaviors:
We implemented a kind of polling as workaround: retry the 'rename' operation until it succeeds.
The polling stops after 20 seconds.
This workaround works in most cases: the file gets replicated within few seconds.
But sometimes — very rarely — 20 seconds are not enough; the replication in S3 takes more time.
Questions
What is the maximum time you observed between a successful PUT operation and complete replication on Amazon S3?
Does Amazon S3 offer a way to 'bypass' replication? (Query 'master' directly?)
Update: this answer uses some older terminology, which i have left in place, for the most part. AWS has changed the friendly name of "US-Standard" to be more consistent with the naming of other regions, but its regional endpoint for IPv4 still has the unusual name s3-external-1.amazonaws.com.
The us-east-1 region of S3 has an IPv4/IPv6 "dual stack" endpoint that follows the standard convention of s3.dualstack.us-east-1.amazonaws.com and if you are IPv6 enabled, this endpoint seems operationally-equivalent to s3-external-1 as discussed below.
The documented references to geographic routing of requests for this region seem to have largely disappeared, without much comment, but anecdotal evidence suggests that the following information is still relevant to that region.
Q. Wasn’t there a US Standard region?
We renamed the US Standard Region to US East (Northern Virginia) Region to be consistent with AWS regional naming conventions.
— https://aws.amazon.com/s3/faqs/#regions
Buckets using the S3 Transfer Acceleration feature use a global-style endpoint of ${bucketname}.s3-accelerate.amazonaws.com and it is not yet evident how this endpoint behaves with regard to us-east-1 buckets and eventual consistency, though it stands to reason that other regions should not be affected by this feature, if enabled. This feature improves transfer throughput for users who are more distant from the bucket by routing requests to the same S3 endpoints but proxying through the AWS "Edge Network," the same system that powers CloudFront. It is, essentially, a self-configuring path through CloudFront but without caching enabled. The acceleration comes from optimized network stacks and keeping the traffic on the managed AWS network for much of its path across the Internet. As such, this feature should have no impact on consistency, if you enable and use it on a bucket... but, as I mentioned, how it interacts with us-east-1 buckets is not yet known.
The US-Standard (us-east-1) region is the oldest, and presumably largest, region of S3, and does play by some different rules than the other, newer regions.
An important and relevant difference is the consistency model.
Amazon S3 buckets in [all regions except US Standard] provide read-after-write consistency for PUTS of new objects and eventual consistency for overwrite PUTS and DELETES. Amazon S3 buckets in the US Standard region provide eventual consistency.
http://aws.amazon.com/s3/faqs/
This is why I assumed you were using US Standard. The behavior you described is consistent with that design constraint.
You should be able to verify that this doesn't happen with a test bucket in another region... but, because data transfer from EC2 to S3 within the same region is free and very low latency, using a bucket in a different region may not be practical.
There is another option that is worth trying, has to do with the inner-workings of US-Standard.
US Standard is in fact geographically-distributed between Virginia and Oregon, and requests to "s3.amazonaws.com" are selectively routed via DNS to one location or another. This routing is largely a black box, but Amazon has exposed a workaround.
You can force your requests to be routed only to Northern Virginia by changing your endpoint from "s3.amazonaws.com" to "s3-external-1.amazonaws.com" ...
http://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region
... this is speculation on my part, but your issue may be exacerbated by geographic routing of your requests, and forcing them to "s3-external-1" (which, to be clear, is still US-Standard), might improve or eliminate your issue.
Update: The advice above has officially risen above speculation, but I'll leave it for historical reference. About a year I wrote the above, Amazon indeed announced that US-Standard does offer read-after-write consistency on new object creation, but only when the s3-external-1 endpoint is used. They explain it as though it's a new behavior, and that may be the case... but it also may simply be a change in the behavior the platform officially supports. Either way:
Starting [2015-06-19], the US Standard Region now supports read-after-write consistency for new objects added to Amazon S3 using the Northern Virginia endpoint (s3-external-1.amazonaws.com). With this change, all Amazon S3 Regions now support read-after-write consistency. Read-after-write consistency allows you to retrieve objects immediately after creation in Amazon S3. Prior to this change, Amazon S3 buckets in the US Standard Region provided eventual consistency for newly created objects, which meant that some small set of objects might not have been available to read immediately after new object upload. These occasional delays could complicate data processing workflows where applications need to read objects immediately after creating the objects. Please note that in US Standard Region, this consistency change applies to the Northern Virginia endpoint (s3-external-1.amazonaws.com). Customers using the global endpoint (s3.amazonaws.com) should switch to using the Northern Virginia endpoint (s3-external-1.amazonaws.com) in order to leverage the benefits of this read-after-write consistency in the US Standard Region. [emphasis added]
https://forums.aws.amazon.com/ann.jspa?annID=3112
If you are uploading a large number of files (hundreds per second), you might also be overwhelming S3's sharding mechanism. For very high numbers of uploads per second, it's important that your keys ("filenames") not be lexically sequential.
Depending on how Amazon handles DNS, you may also want to try another alternate variant of addressing your bucket if your code can handle it.
Buckets in US-Standard can be addressed either with http://mybucket.s3.amazonaws.com/key ... or http://s3.amazonaws.com/mybucket/key ... and the internal implementation of these two could, at least in theory, be different in a way that changes the behavior in a way that would be relevant to your issue.
As you noted, currently there is no guarantee or workaround eventual consistency directly from S3. In this talk from Netflix, the speaker mentions having seen a 7h (extremely rare IMHO) consistency delay. They even created a consistency layer on top of S3, s3mper ,that is open source and might help in your context.
Other than that, as #Michael - sqlbot suggested, us-standard dos not offer read-after-write consistency, and the observed consistency delays may be different there.