Implement Presigned Post URLs #3902

GarrettBeatty · 2025-07-02T19:27:14Z

Description

Implement Presigned POST URL functionality

Motivation and Context

Implement AmazonS3Client is missing Create Presigned Post #1901 & DOTNET-8098.
https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-UsingHTTPPOST.html

Testing

I created a test project in javascript and .net and compared the responses and validated they are the same. You can follow https://github.com/aws/aws-sdk-net/blob/gcbeatty/presigntesting/README_S3_TEST.md if you want to test yourself.
Wrote unit tests and integration tests
Dryrun - 5cec01d1-6a76-49e5-8699-39803aa29592

Types of changes

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to change)

Checklist

My code follows the code style of this project
My change requires a change to the documentation
I have updated the documentation accordingly
I have read the README document
I have added tests to cover my changes
All new and existing tests passed

License

I confirm that this pull request can be released under the Apache 2 license

This reverts commit 2625b99.

This reverts commit d696e4f.

GarrettBeatty · 2025-07-09T18:20:51Z

sdk/src/Services/S3/Custom/AmazonS3Client.Extensions.cs

+
+            // Add the AWS signature fields
+            response.Fields[S3Constants.PostFormDataObjectKey] = request.Key ?? "";
+            response.Fields[S3Constants.PostFormDataPolicy] = signedPolicy.Policy;


please note that S3Constants.PostFormDataPolicy] is Policy with a capital P. All of the other fields are lowercase but i was wanting to re-use this existing field. It doesnt matter if its lowercase or uppercase when sending to s3 though

sdk/src/Services/S3/Custom/AmazonS3Client.Extensions.cs

GarrettBeatty · 2025-07-09T23:57:13Z

sdk/test/IntegrationTests/AWSSDK.IntegrationTests.NetFramework.csproj

@@ -51,6 +51,7 @@
    <Reference Include="System.ComponentModel.DataAnnotations" />
    <Reference Include="System.IO.Compression" />
    <Reference Include="System.Web" />
+    <Reference Include="System.Net.Http"/>


ive been trying to figure out why i need System.Net.Http here if i already have it defined in the S3 integration tests. if anyone knows let me know. without this added here i get

C:\codebuild\tmp\output\src17698009\src\aws-sdk-net\sdk\test\Services\S3\IntegrationTests\CreatePresignedPostTests.cs(303,35): error CS1069: The type name 'ByteArrayContent' could not be found in the namespace 'System.Net.Http'. This type has been forwarded to assembly 'System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' Consider adding a reference to that assembly. [C:\codebuild\tmp\output\src17698009\src\aws-sdk-net\sdk\test\IntegrationTests\AWSSDK.IntegrationTests.NetFramework.csproj]

dscpinheiro · 2025-07-10T00:11:57Z

generator/.DevConfigs/48cf8831-8233-4a7e-853c-5352f8ca948d.json

@@ -0,0 +1,18 @@
+{
+  "core": {
+    "updateMinimum": true,


Do you need the Core section here if the only service being changed is S3? Also, would it make sense to make this a Minor change for S3 since it's a new feature?

im updating code in the generator folder which is why i added core. but i guess you are saying generator is not part of core in this case

i can update to minor

It's not, we normally include Core only if the generator change would impact all (or multiple) services. But in this case your change is S3 only.

fixed in 20bb0e5

normj · 2025-07-14T18:12:49Z

sdk/src/Services/S3/Custom/Model/CreatePresignedPostRequest.cs

+        /// </summary>
+        public CreatePresignedPostRequest() 
+        {
+            Expires = AWSSDKUtils.CorrectedUtcNow.AddHours(1);


Why are we defaulting to an hour? Seems like this should be null requiring users to decide what the expiration should be and give it to us.

thats what javascript does https://github.com/aws/aws-sdk-js-v3/blob/main/packages/s3-presigned-post/src/createPresignedPost.ts#L43

same with python https://github.com/boto/botocore/blob/1bcde58b83bff9dfc2d81bd42a796aa069a0975b/botocore/signers.py#L671

Okay then make sure the documentation for the Expires property says this defaults to an hour from when the CreatePresignedPostRequest instance was created.

updated comment in bcd54bc

Copilot

Pull Request Overview

This PR implements S3 presigned POST URL functionality for the AWS SDK for .NET, enabling browser-based file uploads directly to S3 without requiring server-side processing. The implementation includes comprehensive support for policy conditions, form fields, and AWS signature authentication.

Adds complete presigned POST URL support with three condition types: exact match, starts-with, and content-length-range
Implements proper AWS signature v4 authentication with policy document generation and validation
Provides both synchronous and asynchronous APIs with comprehensive error handling and input validation

Reviewed Changes

Copilot reviewed 15 out of 16 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
S3PostCondition.cs	New model classes for policy conditions with factory methods and JSON serialization
CreatePresignedPostRequest.cs	Request model with bucket name, key, expiration, fields, and conditions
CreatePresignedPostResponse.cs	Response model containing URL and form fields for POST requests
AmazonS3Client.Extensions.cs	Core implementation with policy generation, signing, and endpoint resolution
EndpointResolver.tt	Template update to handle CreatePresignedPostRequest in endpoint resolution
Various test files	Comprehensive unit and integration tests covering all functionality

sdk/test/Services/S3/UnitTests/Custom/S3PostUploadSignedPolicyTests.cs

sdk/test/Services/S3/IntegrationTests/AWSSDK.IntegrationTests.S3.NetFramework.csproj

sdk/src/Services/S3/Custom/AmazonS3Client.Extensions.cs

generator/ServiceClientGeneratorLib/Generators/Endpoints/EndpointResolver.cs

muhammad-othman · 2025-07-17T22:43:48Z

sdk/src/Services/S3/Custom/AmazonS3Client.Extensions.cs

+                throw new AmazonS3Exception("Credentials must be specified, cannot call method anonymously");
+
+            // Resolve credentials asynchronously
+            var immutableCredentials = await credentials.GetCredentialsAsync().ConfigureAwait(false);


Why are we resolving this credential if we aren't using it later?

let me double check this

i updated in 22687c7 to use the resolved credentials. good catch

sdk/src/Services/S3/Custom/AmazonS3Client.Extensions.cs

muhammad-othman · 2025-07-17T22:47:31Z

sdk/src/Services/S3/Custom/AmazonS3Client.Extensions.cs

+        {
+            ValidateCreatePresignedPostRequest(request);
+
+            var credentials = Config.DefaultAWSCredentials ?? DefaultIdentityResolverConfiguration.ResolveDefaultIdentity<AWSCredentials>();


Same S3Express credentials comment.

GarrettBeatty · 2025-07-18T14:03:47Z

doing one final dry run before merging fe2e67f3-2b95-44c6-9d6f-0b1a64e760d7

GarrettBeatty changed the title ~~presigned post~~ Implement Presigned Post URLs Jul 2, 2025

GarrettBeatty force-pushed the gcbeatty/presignedpostbcl branch from 6c58f61 to dd78028 Compare July 8, 2025 02:34

GarrettBeatty force-pushed the gcbeatty/presignedpostimpl branch from 2625b99 to 8a43d25 Compare July 8, 2025 20:30

Base automatically changed from gcbeatty/presignedpostbcl to development July 8, 2025 23:29

GarrettBeatty force-pushed the gcbeatty/presignedpostimpl branch from 0dcb789 to 509c246 Compare July 8, 2025 23:31

GarrettBeatty added 22 commits July 9, 2025 11:26

presigned post

1d43e08

update comments

84354b2

update comments

0b12d72

update comments

d7fa60a

use public set

f5732f7

add unit tests

ca6fefa

Fix duplicate fields

56151bf

Fix url pathing

805b14d

Update fields and conditions logic to match python

78ac820

add integration tests

3de290a

Revert "Update fields and conditions logic to match python"

5084f72

This reverts commit 2625b99.

update it test

300557e

remove s3 express logic

ca23784

restructre it tests

4580173

add dev config

eb59489

update comments

f2c464e

fix test namespace

042a320

fix test namespace

7583c33

add replacement in key

e4bf85a

remove async tests from netframework

3ef3e3b

Revert "remove async tests from netframework"

d8b179d

This reverts commit d696e4f.

Remove async api check

2ee4790

GarrettBeatty force-pushed the gcbeatty/presignedpostimpl branch from 7a5fda0 to 2ee4790 Compare July 9, 2025 15:28

GarrettBeatty added 2 commits July 9, 2025 13:06

add System.Net.Http reference

3cd831d

add comment

87acbd6

GarrettBeatty commented Jul 9, 2025

View reviewed changes

GarrettBeatty added 3 commits July 9, 2025 14:24

update comments

29a99ef

fix build

3b5fadd

update comments

cac8fcc

GarrettBeatty marked this pull request as ready for review July 9, 2025 21:02

GarrettBeatty requested review from normj and boblodgett July 9, 2025 21:02

GarrettBeatty commented Jul 9, 2025

View reviewed changes

sdk/src/Services/S3/Custom/AmazonS3Client.Extensions.cs Show resolved Hide resolved

GarrettBeatty commented Jul 9, 2025

View reviewed changes

dscpinheiro reviewed Jul 10, 2025

View reviewed changes

GarrettBeatty requested review from muhammad-othman and removed request for boblodgett July 13, 2025 01:18

normj reviewed Jul 14, 2025

View reviewed changes

GarrettBeatty requested a review from Copilot July 15, 2025 14:21

Copilot AI reviewed Jul 15, 2025

View reviewed changes

GarrettBeatty added 2 commits July 15, 2025 17:24

update dev config

20bb0e5

update comment

bcd54bc

GarrettBeatty requested a review from normj July 15, 2025 21:27

Update 48cf8831-8233-4a7e-853c-5352f8ca948d.json

2988ccc

normj approved these changes Jul 16, 2025

View reviewed changes

muhammad-othman reviewed Jul 17, 2025

View reviewed changes

sdk/src/Services/S3/Custom/AmazonS3Client.Extensions.cs Show resolved Hide resolved

muhammad-othman reviewed Jul 17, 2025

View reviewed changes

use immutable credentials

22687c7

muhammad-othman approved these changes Jul 18, 2025

View reviewed changes

GarrettBeatty merged commit bb84f7c into development Jul 18, 2025
3 checks passed

GarrettBeatty deleted the gcbeatty/presignedpostimpl branch July 18, 2025 15:50

This was referenced Jul 21, 2025

Add CreatePresignedPostAsync to interface definitions #3926

Merged

Dotnetv4: Add CreatePresignedPost in S3 awsdocs/aws-doc-sdk-examples#7536

Open

Implement Presigned Post URLs #3902

Implement Presigned Post URLs #3902

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GarrettBeatty commented Jul 2, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Description

Motivation and Context

Testing

Types of changes

Checklist

License

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GarrettBeatty Jul 10, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Pull Request Overview

Reviewed Changes

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GarrettBeatty commented Jul 18, 2025

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GarrettBeatty commented Jul 2, 2025 •

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GarrettBeatty Jul 10, 2025 •

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