s3: fix Cloudflare R2 integration tests after SDKv2 update #4989

Cloudflare will normally automatically decompress files with
`Content-Encoding: gzip` when downloaded. This is not what AWS S3 does
and it breaks the integration tests.

This fudges the integration tests to upload the test file with
`Cache-Control: no-transform` on Cloudflare R2 and puts a note in the
docs about this problem.

backend/s3/s3_internal_test.go

@@ -60,6 +60,16 @@ func (f *Fs) InternalTestMetadata(t *testing.T) {
 		// "tier" - read only
 		// "btime" - read only
 	}
+	// Cloudflare insists on decompressing `Content-Encoding: gzip` unless
+	// `Cache-Control: no-transform` is supplied. This is a deviation from
+	// AWS but we fudge the tests here rather than breaking peoples
+	// expectations of what Cloudflare does.
+	//
+	// This can always be overridden by using
+	// `--header-upload "Cache-Control: no-transform"`
+	if f.opt.Provider == "Cloudflare" {
+		metadata["cache-control"] = "no-transform"
+	}
 	obj := fstests.PutTestContentsMetadata(ctx, t, f, &item, true, contents, true, "text/html", metadata)
 	defer func() {
 		assert.NoError(t, obj.Remove(ctx))

docs/content/s3.md

@@ -2388,7 +2388,14 @@ acl = private
 Now run `rclone lsf r2:` to see your buckets and `rclone lsf
 r2:bucket` to look within a bucket.
 
-For R2 tokens with the "Object Read & Write" permission, you may also need to add `no_check_bucket = true` for object uploads to work correctly.
+For R2 tokens with the "Object Read & Write" permission, you may also
+need to add `no_check_bucket = true` for object uploads to work
+correctly.
+
+Note that Cloudflare decompresses files uploaded with
+`Content-Encoding: gzip` by default which is a deviation from what AWS
+does. If this is causing a problem then upload the files with
+`--header-upload "Cache-Control: no-transform"`
 
 ### Dreamhost