Constants should always be only assigned once. The logical OR assignment
of a constant is a relic of the past before we used zeitwerk for
autoloading and had bugs where a file could be loaded twice resulting in
constant redefinition warnings.
Previously we were opening the file handles, then putting them in a queue for upload. If that queue grows too large, we can hit a maximum open files limit.
This commit opens the file handle 'just in time', so the maximum number of open handles is equal to the upload concurrency (20).
AWS recommends running buckets without ACLs, and to use resource policies to manage access control instead.
This is not a bad idea, because S3 ACLs are whack, and while resource policies are also whack, they're a more constrained form of whack.
Further, some compliance regimes get antsy if you don't go with the vendor's recommended settings, and arguing that you need to enable ACLs on a bucket just to store images in there is more hassle than it's worth.
The new site setting (s3_use_acls) cannot be disabled when secure
uploads is enabled -- the latter relies on private ACLs for security
at this point in time. We may want to reexamine this in future.
Uploading lots of small files can be made significantly faster by parallelizing the `s3.put_object` calls. In testing, an UPLOAD_CONCURRENCY of 10 made a large restore 10x faster. An UPLOAD_CONCURRENCY of 20 made the same restore 18x faster.
This commit is careful to parallelize as little as possible, to reduce the chance of concurrency issues. In the worker threads, no database transactions are performed. All modification of shared objects is controlled with a mutex.
Unfortunately we do not have any existing tests for the `ToS3Migration` class. This change has been tested with a large site backup (120k uploads totalling 45GB)
`GlobalSetting.relative_url_root` comes from the destination site. We
can't be sure whether it was the same on the original site. It's safer
to use a wildcard here, so we can backup/restore sites with different
relative_url_root values.
* strip out the href and xlink:href attributes from use element that
are _not_ anchors in svgs which can be used for XSS
* adding the content-disposition: attachment ensures that
uploaded SVGs cannot be opened and executed using the XSS exploit.
svgs embedded using an img tag do not suffer from the same exploit
The `uplaods:migrate_to_s3` rake task should always use the environment variables, because you usually don't want to break your site's uploads during the migration. But restoring a backup should work with site settings as well as environment variables, otherwise you can't restore uploads to S3 from the web interface.
The rake task aborted the migration with "Already migrated" when all upload URLs linked to the correct S3 bucket even though the files didn't exist on S3. By removing the first check we force the rake task to check for the existance of uploads on S3.
