Dealing with null bytes when creating ec2 with user_data using fog

Question

I am trying to provision an ec2 instance using fog, here is the code that I am using:

compute = Fog::Compute.new provider: 'AWS',
            region: 'us-east-1', aws_access_key_id: ACCESS_KEY,
            aws_secret_access_key: SECRET_ACCESS_KEY
options = {
          image_id: 'ami-xxxxxx',
          flavor_id: 'm1.small',
          #custom security group created in AWS Account with open ports
          groups: ['myGroup'],
          private_key_path: '~/.ssh/id_rsa',
          public_key_path: '~/.ssh/id_rsa.pub',
          username: 'ec2-user',
          user_data: File.read(Rails.root.join('public', 'somefile.zip'))
        }
compute.servers.bootstrap options

When, I run this. I get following error:

Fog::JSON::EncodeError: string contains null byte
from /home/gaurish/.rvm/gems/ruby-2.0.0-p247/gems/multi_json-1.8.2/lib/multi_json/adapters/oj.rb:20:in `dump'

As you may notice, above. I am supplying a ZIP file for user_data option. And this is what I think the problem occurs. My guess is that the zip file or encoding it to base64 somehow adds a null byte("\0") due to which Oj can't encode it to JSON format.

Now,

• Can anyone verify if its a bug in fog or am I doing anything wrong?
• Any workarounds to avoid null bytes?

Versions used:

• Fog 1.19
• multi_json-1.8.2
• oj-2.2.3

Answer 1

I have solved this issue. here is how:

file = File.open(path, 'rb') #path => path to zip file
contents = file.read
file.close
user_data = Base64.encode64 contents

now, this user_data can be safely passed into options[:user_data] hash without null byte errors. this issue is being tracked here:

https://github.com/fog/fog/issues/2506