AWS::S3::Errors::InvalidAccessKeyId with valid credentials - ruby-on-rails

Question

I'm getting the following error when trying to upload a file to an S3 bucket:
AWS::S3::Errors::InvalidAccessKeyId: The AWS Access Key Id you provided does not exist in our records.
The file exists, the bucket exists, the bucket allows uploads, the credentials are correct, and using CyberDuck with the same credentials i can connect and upload files to that bucket just fine. Most answers around here point to the credentials being overridden by environment variables, that is not the case here, i've tried passing them directly as strings, and outputting them just to make sure, it's the right credentials.
v1
AWS.config(
:access_key_id => 'key',
:secret_access_key => 'secret'
)
s3 = AWS::S3.new
bucket = AWS::S3.new.buckets['bucket-name']
obj = bucket.objects['filename']
obj.write(file: 'path-to-file', acl:'private')
this is using the v1 version of the gem (aws-sdk-v1) but I've tried also using v3 and I get the same error.
v3
Aws.config.update({
region: 'eu-west-1',
credentials: Aws::Credentials.new('key_id', 'secret')
})
s3 = Aws::S3::Resource.new(region: 'eu-west-1')
bucket = s3.bucket('bucket-name')
obj = bucket.object('filename')
ok = obj.upload_file('path-to-file')
Note: the error is thrown on the obj.write line.
Note 2: This is a rake task from a Ruby on Rails 4 app.

Answer 1

Finally figured it out, the problem was that because we are using a custom endpoint the credentials were not found, I guess that works differently with custom endpoints.
Now to specify the custom endpoint you'll need to use a config option that for some reason is not documented (or at least I didn't find it anywhere), I actually had to go through paperclip's code to see how those guys were handling this.
Anyway here's how the config for v1 looks like with the added config for the endpoint:
AWS.config(
:access_key_id => 'key',
:secret_access_key => 'secret',
:s3_endpoint => 'custom.endpoint.com'
)
Hopefully that will save somebody some time.