Resolves: #306

Problem

When virtual_host and bucket_as_host are set in the ExAws configuration, the presigned_url and presigned_post functions ignore these settings and default to false. This causes bucket names to appear twice in generated URLs when using custom domain buckets.

Example issue:

• Config: virtual_host: true, bucket_as_host: true
• Generated URL: https://my-bucket.com/my-bucket.com/path/to/file
• Expected URL: https://my-bucket.com/path/to/file

This breaks multipart uploads and other S3 operations when using custom domains.

Root Cause

The presigned_url and presigned_post functions were hardcoded to default to false:

# Before - ignores config
virtual_host = Keyword.get(opts, :virtual_host, false)
bucket_as_host = Keyword.get(opts, :bucket_as_host, false)

Solution

Modified both functions to use config values as defaults while still allowing explicit options to override them:

# After - reads from config
virtual_host = Keyword.get(opts, :virtual_host, config[:virtual_host] || false)
bucket_as_host = Keyword.get(opts, :bucket_as_host, config[:bucket_as_host] || false)

Changes

1. Fixed presigned_url/5: Now reads virtual_host and bucket_as_host from config as defaults
2. Fixed presigned_post/4: Now reads virtual_host and bucket_as_host from config as defaults
3. Added comprehensive tests: Verify that config values are properly used when options are not provided

Testing

• ✅ Explicit options still override config values
• ✅ Config values are used as defaults when options not provided
• ✅ Backward compatibility maintained
• ✅ No more double bucket names in URLs with bucket_as_host=true

Related

• Fixes initiate_multipart_upload ignores the bucket_as_host #306
• Complements PR Fix bucket_as_host with virtual_host causing double bucket in URLs ex_aws#1162 (fixes regular S3 operations)

This fix ensures that presigned URLs work correctly with custom domain buckets when bucket_as_host=true is set in the ExAws configuration.