Posting object to Google Cloud Storage doesn't replace ${filename} variable - ruby

Question

As described here https://cloud.google.com/storage/docs/xml-api/post-object
I can use ${filename} as part of the key when uploading a file to GCS from the browser (using a signed request).
That's great, because it's the exact same variable S3 uses. But - a problem. It doesn't actually replace ${filename} with the name of the file when I upload. This works perfectly on S3, but with GCS I literally get $%7Bfilename%7D as the key in the response - clearly it's not replacing this with the correct value.
I'm building the request like so:
export function uploadVideo(video) {
return new Promise((resolve, reject) => {
if (!video) {
resolve(null);
return;
}
// this fetches a presigned post object from the server:
request.get('/presigned_post')
.query({format: 'json'})
.end((err, response)=> {
if (!err && response.ok) {
request
.post(`https://${response.body.url.host}/`)
.field(response.body.fields)
.field('Content-Type', image.type)
.attach('file', image, image.name)
.end((err, response) => {
if (err) {
console.log("Error uploading image: ", err);
reject(err);
} else {
resolve({
location: response.text.match('<Location>' + '(.*?)' + '</Location>')[1],
bucket: response.text.match('<Bucket>' + '(.*?)' + '</Bucket>')[1],
key: response.text.match('<Key>' + '(.*?)' + '</Key>')[1],
checksum: response.text.match('<ETag>"' + '(.*?)' + '"</ETag>')[1]
});
}
});
}
});
});
}
The key is some_folder/${filename} and this is included in the form data to google (in response.fields).
You can see I am providing the filename with .attach('file', image, image.name). It is uploading correctly, just not replacing the ${filename} var.
edit
I have narrowed down the issue more. We query S3 and GCS to get the fields in the presigned post. With S3, if I give a key of ${filename} then I get exactly that returned in the fields:
def presigned_post(bucket_name:, key:, **opts)
response = s3_resource.
bucket(bucket_name).
presigned_post(key: key, content_type_starts_with: '', **opts)
{
fields: response.fields,
url: { host: URI.parse(response.url).host }
}
end
Fields here will contain "key"=>"${filename}".
However in the GCS case, the following code returns :key=>"$%7Bfilename%7D" in the fields:
# https://cloud.google.com/storage/docs/xml-api/post-object#usage_and_examples
# https://www.rubydoc.info/gems/google-cloud-storage/1.0.1/Google/Cloud/Storage/Bucket:post_object
def presigned_post(bucket_name:, key:, acl:, success_action_status:, expiration: nil)
expiration ||= (Time.now + 1.hour).iso8601
policy = {
expiration: expiration,
conditions: [
["starts-with", "$key", "" ],
["starts-with", "$Content-Type", "" ],
{ acl: acl },
{ success_action_status: success_action_status }
]
}
post_obj = get_bucket!(bucket_name).post_object(key, policy: policy)
url_obj = { host: URI.parse(post_obj.url).host }
# Have to manually merge in these fields
fields = post_obj.fields.merge(
acl: acl,
success_action_status: success_action_status
)
return { fields: fields, url: url_obj }
end
If i manually change the key in the GCS request fields, then it works. Is that really what I'm supposed to do?

Answer 1

A fix for this issue was released in google-cloud-storage v1.24.0.

Answer 2

Figured out the issue is caused by:
def ext_path
URI.escape "/#{#bucket}/#{#path}"
end
in lib/google/cloud/storage/file.rb of the google-cloud-ruby-gem.
This is called by def post_object in that same file.
I am going to raise an issue on their Github page.