Error http 422 with DirectUpload / ActiveStorage / Rails - rails-activestorage

Question

I try to add some images with ajax via DirectUpload / ActiveStorage / Rails 6.
I use the prerequisites into of ActiveStorage support, for use DirectUpload with Jquery :
https://edgeguides.rubyonrails.org/active_storage_overview.html#integrating-with-libraries-or-frameworks
const upload = new DirectUpload(file, url)
upload.create((error, blob) => {
if (error) {
// Handle the error
} else {
// Add an appropriately-named hidden input to the form with a
[..]
console.log(blob.key);
}
})
On my host, it works for all files. But when I try to publish my app into my hoster, I have an error for some files, always the same, after the request of DirectUpload :
Completed 422 Unprocessable Entity in 2ms (ActiveRecord: 0.0ms | Allocations: 689)
I looked the XHR requests into my webtools browser, but the payload seems the same into a file which works and another which fails :
{id: 219, key: "v2v1aqlk8gyygcc4smjeh0bbuc59", filename: "groupama logo.jpeg",…}
id: 219
key: "v2v1aqlk8gyygcc4smjeh0bbuc59"
filename: "logo.jpeg"
content_type: "image/jpeg"
metadata: {}
byte_size: 17805
checksum: "3GIVi2kNKClfH+d9HGYOfkA=="
created_at: "2020-04-09T08:25:40.000+02:00"
signed_id: "eyJfcmFpbHMiOnsibWVzc2zaFnZSI6IkJBaHBBZHM9IiwiZXhwIjpudWxsLCJwdXIiOiJibG9iX2lkIn19--7c0750cb8c86a955a04fa9a11dc5389cdeb5e7b0"
attachable_sgid: "BAh7CEkiCGdpZAY6BkVUSSIxsaZ2lkOi8vYXBwL0FjdGl2ZVN0b3JhZ2U6OkJsb2IvMjE5P2V4cGlyZXNfaW4GOwBUSSIMcHVycG9zZQY7AFRJIg9hdHRhY2hhYmxlBjsAVEkiD2V4cGlyZXNfYXQGOwBUMA==--64a945c38dc5d85c05156da50b9c38819b106e10"
direct_upload: {,…}
url: "http://localhost:8491/rails/active_storage/disk/eyJfcmFpbHMiOnsibWVzc2FnZSI6IkJBaDdDVG9JYTJWNVNTSWhkakoyTVdGeGJHczRaM2w1WjJOak5ITnRhbVZvTUdKaWRXTTFPUVk2QmtWVU9oRmpiMjaUwWlc1MFgzUjVjR1ZKSWc5cGJXRm5aUzlxY0dWbkJqc0dWRG9UWTI5dWRHVnVkRjlzWlc1bmRHaHBBbzFGT2cxamFHVmphM04xYlVraUhUTkhTVlpwTW10T1MwTnNaa2dyT1VoSFdVOW1hMEU5UFFZN0JsUT0iLCJleHAiOiIyMDIwLTA0LTA5VDA2OjMwOjQwLjg5NFoiLCJwdXIiOiJibG9iX3Rva2VuIn19--a2acedc0924f735c5cc08db8c4b76f76accc3c8d"
headers: {Content-Type: "image/jpeg"}
I tried this solution, by the monkey patch doesn't works for me, and another solution seems not working :
Rails API ActiveStorage DirectUpload produce 422 Error InvalidAuthenticityToken
I noticed, when I try to upload the logo image file without use DirectUpdate into input file, the file is correctly well send to my server.
= f.file_field :logos, direct_upload: true
Do you have any idea to test ?

Answer 1

My issue was coming with the IO which was use for copy the file. Into the ActiveStorage::DiskController#update, Rails use the request.body and IO.CopyStream for create the file, and a checksum file was done for verifiy the file created.
And the check fail and throw the 422 http error.
I noticed than the IO stream, in dev mode was a String_IO, whereas on my hoster, the IO was a Uswgi_IO. Because my hoster deliver the ruby on rails application with Uswgi.
The uwsgi_io not contains a length or size methods, and when ActiveStorage create the file with this IO, the size of file was weird. Weirdly too large.
I noticed if the RAW_POST_DATA was assign, then the request.body return a String_IO. And into the request.raw_post method, the body was read directly with the request.content_length :
raw_post_body.read(content_length)
https://api.rubyonrails.org/classes/ActionDispatch/Request.html#method-i-body
I created a new controller which inherits of ActiveStorage::DiskController, in order to assign the RAW_POST_DATA, before the Disk#update action.
class UploadController < ActiveStorage::DiskController
def update
request.env['RAW_POST_DATA'] = request.body.read(request.content_length)
super
end
end
And after, I override the ActiveStorage disk#update route by mine :
put '/rails/active_storage/disk/:encoded_token', to: 'upload#update
And it works !
ActionText works with ActiveStorage for store the images, and I had the same issue with the images too large.
My patch allows to make works ActionText on my hoster too.

Answer 2

Kudos for finding the culprit here, I was having the exact same issue on a uwsgi setup and I was trying to figure out why the content length was different when I found your post. Thanks for sharing !
I just took a slightly different approach with the fix as I didn't want to hack the AS routes, so I created a config/initializers file with the following code :
Rails.configuration.to_prepare do
ActiveStorage::DiskController.class_eval do
before_action :set_raw_post_data, only: :update
def set_raw_post_data
request.env['RAW_POST_DATA'] = request.body.read(request.content_length)
end
end
end
Maybe it would be worth creating an issue in https://github.com/unbit/uwsgi to let them know about this ?