[RaphaelFakhri]

Closes #10577

Change Description

Background

With x-amz-metadata-directive: REPLACE, S3 replaces the object's content type with the Content-Type sent on the copy request. Copying an object onto itself with a new content type is the usual way to fix a wrong one. The lakeFS S3 gateway replaces only the user metadata and keeps the source content type.

Bug Fix

1. Problem: aws s3api copy-object --metadata-directive REPLACE --content-type application/json through the S3 gateway keeps the source content type (for example text/plain). The new user metadata is applied.
2. Root cause: handleCopy passes only the x-amz-meta-* headers to Catalog.CopyEntry, and CopyEntry copies ContentType from the source entry in every case.
3. Solution: Catalog.CopyEntry (and cloneEntry) take a contentType argument and set it on the new entry when replaceSrcMetadata is true, together with the metadata. The gateway passes the request's Content-Type. As with PUT, an empty value stores no content type and reads return the default. The API copy handler passes "" with replaceSrcMetadata set to false, so its behavior does not change.

Testing Details

• New test TestCopyObjectReplaceContentType in pkg/gateway/handler_test.go. It uploads an object with text/plain through the gateway, copies it with REPLACE and with COPY while sending Content-Type: application/json, and checks the Content-Type that HEAD returns: application/json for REPLACE, text/plain for COPY.
• Without the fix, the replace subtest fails (expected: "application/json", actual: "text/plain") and the copy subtest passes. With the fix, both pass.
• GetBasicHandler in pkg/gateway/testutil now gives the handler the catalog's block adapter when USE_BLOCK_ADAPTER is unset or mem. Each in-memory adapter keeps its own data, so before this change a copy through the test handler could not read an object written through the same handler. When USE_BLOCK_ADAPTER names another adapter, the handler still gets that adapter.
• go test ./pkg/gateway/... ./pkg/catalog/, go test -run Copy ./pkg/api/, go build ./..., go vet, and go tool golangci-lint run ./pkg/gateway/... ./pkg/catalog/ ./pkg/api/ (0 issues) pass.

Breaking Change?

No API, CLI, or client change. S3 gateway clients that send REPLACE now get the request's Content-Type on the copy, which matches S3.

Additional info

Reproduction from the issue, against the S3 gateway:

aws s3api put-object --bucket rep --key main/data.json --body data.json --content-type text/plain --metadata '{"k":"v"}'
aws s3api copy-object --bucket rep --key main/data.json --copy-source rep/main/data.json \
  --metadata-directive REPLACE --content-type application/json --metadata '{"k":"w"}'
aws s3api head-object --bucket rep --key main/data.json --query ContentType --output text
# before: text/plain
# after:  application/json

Contact Details

mail@raphaelfakhri.com

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