Rails - Upload an Object Using a Pre-Signed URL (AWS SDK for Ruby)

presigned_url.rb

Aws.config.update({
  region: 'us-east-1',
  credentials: Aws::Credentials.new(ENV['AWS_ACCESS_KEY_ID'], ENV['AWS_SECRET_ACCESS_KEY'])
})

S3_BUCKET = Aws::S3::Resource.new.bucket(ENV['S3_BUCKET'])

@post = S3_BUCKET.presigned_post(key: "uploads/#{SecureRandom.uuid}/${filename}", success_action_status: '201', acl: 'public-read')

post = Aws::S3::Resource.new.bucket("fake").presigned_post(key: "uploads/#{SecureRandom.uuid}/${filename}", success_action_status: '201', acl: 'public-read')
#<Aws::S3::PresignedPost:0x007f90c1cadf88 @credentials=#<Aws::Credentials access_key_id="a">, @bucket_region="us-east-1", @bucket_name="fake", @url="https://fake.s3.amazonaws.com", @fields={"key"=>"uploads/f8f0cb43-9b34-4e76-b3e6-c930f1438ec6/${filename}", "success_action_status"=>"201", "acl"=>"public-read"}, @key_set=true, @signature_expiration=2016-12-29 14:04:58 -0500, @conditions=[{"bucket"=>"fake"}, ["starts-with", "$key", "uploads/f8f0cb43-9b34-4e76-b3e6-c930f1438ec6/"], {"success_action_status"=>"201"}, {"acl"=>"public-read"}]>

# POST to @post.url
# send all @post.fields (key => value)
# send image as file (field name)

# Response
# <?xml version="1.0" encoding="UTF-8"?>
# <PostResponse>
#     <Location>https://s3.amazonaws.com/S3_BUCKET/uploads/RANDOMLY_GENERATED/image.png</Location>
#     <Bucket>S3_BUCKET</Bucket>
#     <Key>uploads/RANDOMLY_GENERATED/image.png</Key>
#     <ETag>"1234567890asdfghjkl"</ETag>
# </PostResponse>

# "//#{@post.url}/<Key></Key>"

require 'aws-sdk-s3'

#credentials below for the IAM user I am using
s3 = Aws::S3::Client.new(
  region:               'us-west-2', #or any other region
  access_key_id:        AWS_ACCESS_KEY_ID,
  secret_access_key:    AWS_SECRET_ACCESS_KEY
)

signer = Aws::S3::Presigner.new(client: s3)
url = signer.presigned_url(
  :put_object,
  bucket: S3_BUCKET_NAME,
  key: "${filename}-#{SecureRandom.uuid}"
)

https://stackoverflow.com/questions/44741473/recommended-way-to-generate-a-presigned-url-to-s3-bucket-in-ruby