S3 File Resource for Chef

recipe.rb

# Source accepts http/https or the protocol region:// with the host as the bucket
# access_key_id and secret_access_key are just that
# Note resource name has changed from s3_file to s3_aware_remote_file

# for the eu-west-1 region: 
s3_aware_remote_file "/var/bulk/the_file.tar.gz" do
  source "s3-eu-west-1://your.bucket/the_file.tar.gz"
  access_key_id your_key
  secret_access_key your_secret
  owner "root"
  group "root"
  mode 0644
end

# for the us-east-1 region: 
s3_aware_remote_file "/var/bulk/the_file.tar.gz" do
  source "s3://your.bucket/the_file.tar.gz"
  access_key_id your_key
  secret_access_key your_secret
  owner "root"
  group "root"
  mode 0644
end

# for the http(s):
s3_aware_remote_file "/var/bulk/the_file.tar.gz" do
  source "http://hostname/path/the_file.tar.gz"
  access_key_id your_key
  secret_access_key your_secret
  owner "root"
  group "root"
  mode 0644
end

s3_file.rb

# coding: utf-8
#
# Author:: Christopher Peplin (<[email protected]>)
# Author:: Ivan Porto Carrero (<[email protected]>)
# Author:: Paul Poulain (<[email protected]>)
# Copyright:: Copyright (c) 2010 Bueda, Inc.
# Copyright:: Copyright (c) 2011 Mojolly Ltd.
# Copyright:: Copyright (c) 2011 mirada plc.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

require 'digest/sha1'
require 'openssl'
require 'cgi'
require 'base64'
require "net/http"
require "net/https"
require 'tempfile'

## The S3Sign class generates signed URLs for Amazon S3
class S3Sign

  def initialize(aws_access_key_id, aws_secret_access_key)
    @aws_access_key_id = aws_access_key_id
    @aws_secret_access_key = aws_secret_access_key
  end

  # builds the canonical string for signing.
  def canonical_string(method, path, headers={}, expires=nil)
    interesting_headers = {}
    headers.each do |key, value|
      lk = key.downcase
      if lk == 'content-md5' or lk == 'content-type' or lk == 'date' or lk =~ /^x-amz-/
        interesting_headers[lk] = value.to_s.strip
      end
    end

    # these fields get empty strings if they don't exist.
    interesting_headers['content-type'] ||= ''
    interesting_headers['content-md5'] ||= ''
    # just in case someone used this.  it's not necessary in this lib.
    interesting_headers['date'] = '' if interesting_headers.has_key? 'x-amz-date'
    # if you're using expires for query string auth, then it trumps date (and x-amz-date)
    interesting_headers['date'] = expires if not expires.nil?

    buf = "#{method}\n"
    interesting_headers.sort { |a, b| a[0] <=> b[0] }.each do |key, value|
      buf << ( key =~ /^x-amz-/ ? "#{key}:#{value}\n" : "#{value}\n" )
    end
    # ignore everything after the question mark...
    buf << path.gsub(/\?.*$/, '')
    # ...unless there is an acl or torrent parameter
    if    path =~ /[&?]acl($|&|=)/     then buf << '?acl'
    elsif path =~ /[&?]torrent($|&|=)/ then buf << '?torrent'
    end
    return buf
  end

  def hmac_sha1_digest(key, str)
    OpenSSL::HMAC.digest(OpenSSL::Digest::SHA1.new, key, str)
  end

  # encodes the given string with the aws_secret_access_key, by taking the
  # hmac-sha1 sum, and then base64 encoding it. then url-encodes for query string use
  def encode(str)
    CGI::escape(Base64.encode64(hmac_sha1_digest(@aws_secret_access_key, str)).strip)
  end

  # generate a url to put a file onto S3
  def put(bucket, key, expires_in=0, headers={})
    return generate_url('PUT', "/#{bucket}/#{CGI::escape key}", expires_in, headers)
  end

  # generate a url to put a file onto S3
  def get(bucket, key, expires_in=0, headers={})
    return generate_url('GET', "/#{bucket}/#{CGI::escape key}", expires_in, headers)
  end

  # generate a url with the appropriate query string authentication parameters set.
  def generate_url(method, path, expires_in, headers)
    #log "path is #{path}"
    expires = expires_in.nil? ? 0 : Time.now.to_i + expires_in.to_i
    canonical_string = canonical_string(method, path, headers, expires)
    encoded_canonical = encode(canonical_string)
    arg_sep = path.index('?') ? '&' : '?'
    return path + arg_sep + "Signature=#{encoded_canonical}&" + 
           "Expires=#{expires}&AWSAccessKeyId=#{@aws_access_key_id}"
  end

end

class Chef
  class Provider
    class S3AwareRemoteFile < Chef::Provider::RemoteFile

      def action_create
        # Only do the S3 logic if it looks like an S3 URL (case insensitive)
        if @new_resource.source.match(/^s3/i)
          Chef::Log.debug("Checking #{@new_resource} for changes")

          if current_resource_matches_target_checksum?
            Chef::Log.debug("File #{@new_resource} checksum matches target checksum (#{@new_resource.checksum}), not updating")
          else
            Chef::Log.debug("File #{@current_resource} checksum didn't match target checksum (#{@new_resource.checksum}), updating")
            fetch_from_s3(@new_resource.source) do |raw_file|
              if matches_current_checksum?(raw_file)
                Chef::Log.debug "#{@new_resource}: Target and Source checksums are the same, taking no action"
              else
                backup_new_resource
                Chef::Log.debug "copying remote file from origin #{raw_file.path} to destination #{@new_resource.path}"
                FileUtils.cp raw_file.path, @new_resource.path
                @new_resource.updated_by_last_action true
              end
            end
          end
          enforce_ownership_and_permissions

          @new_resource.updated
        else 
          # Appears not to be an S3 URL. Delegate to the superclass.
          self.class.superclass.instance_method("action_create").bind(self).call
        end
      end

      def fetch_from_s3(source)
        begin
          region, bucket, key = URI.split(source).compact
          key = key[1..-1]
          expires = @new_resource.expires || 30
          s3 = S3Sign.new(@new_resource.access_key_id, @new_resource.secret_access_key)
          access_key = @new_resource.access_key_id
          secret_key = @new_resource.secret_access_key
          headers = @new_resource.headers || {}
          Chef::Log.debug("Downloading #{key} from S3 bucket #{bucket}")
          file = Tempfile.new("chef-s3-file")
          host = "#{region||"s3"}.amazonaws.com"
          Chef::Log.debug("Connecting to s3 host: #{host}:443")
          http_client = Net::HTTP.new(host, 443)
          http_client.use_ssl = true
          http_client.verify_mode = OpenSSL::SSL::VERIFY_NONE
          http_client.start do |http|
            pth = s3.get(bucket, key, expires, headers)
            Chef::Log.debug("Requesting #{pth}")
            http.request_get(pth) do |res|
              res.read_body do |chunk|
                file.write chunk
              end
            end
          end
          Chef::Log.debug("File #{key} is #{file.size} bytes on disk")
    
          # If the file size is less than 1k, check the file didn't contain any errors (it would fail the checksum test if configured
          # but a helpful error message would be nice)
          # Error messages can look like this:
          #   <?xml version="1.0" encoding="UTF-8"?>
          #   <Error><Code>AccessDenied</Code><Message>Access Denied</Message><RequestId>FCD8E2E772C5583B</RequestId><HostId>jBnN9pZOHGb9xov9mbXhfsPKReFUjYZg9A240scOGQkSa2S/ekGMl2JZCeoXuEie</HostId></Error>
          # or maybe this:
          #   <?xml version="1.0" encoding="UTF-8"?>
          #   <Error><Code>NoSuchKey</Code><Message>The specified key does not exist.</Message><Key>not_here/Test.txtd</Key><RequestId>6BA9A12E179BD984</RequestId><HostId>K4Osi2DIoQ8I41RpHRqgp0doVMBgTpSorKSl+zFQQXJJWHyBv5YfHnFkH9DBQGbK</HostId></Error>
          if file.size < 1000
            file.rewind
            fileContents = file.read
            match = fileContents.match(/<Error><Code>(.*)<\/Code><Message>(.*)<\/Message>.*<\/Error>/)
            Chef::Log.warn("Match #{match}")
            if match
              Chef::Log.error("Got an S3 error downloading the file: #{match[1]} - #{match[2]}")
              Chef::Log.error("Response: #{fileContents}")
              raise "Error downloading file from S3: #{match[1]} (#{match[2]})"
              nil
            end
          end

          begin
            yield file
          ensure
            file.close
          end     
        rescue URI::InvalidURIError
          Chef::Log.warn("Expected an S3 URL but found #{source}")
          nil
        end
      end
    end
  end
end

class Chef
  class Resource
    class S3AwareRemoteFile < Chef::Resource::RemoteFile
      def initialize(name, run_context=nil)
        super
        @resource_name = :s3_aware_remote_file
      end

      def provider
        Chef::Provider::S3AwareRemoteFile
      end

      def access_key_id(args=nil)
        set_or_return(
          :access_key_id,
          args,
          :kind_of => String
        )
      end
        
      def secret_access_key(args=nil)
        set_or_return(
          :secret_access_key,
          args,
          :kind_of => String
        )
      end

      def headers(args={})
        set_or_return(
          :headers,
          args,
          :kind_of => Hash
        )
      end

      def expires(args=30)
        set_or_return(
          :expires,
          args,
          :kind_of => Integer
        )
      end
    end 
  end
end

# vim: set si ts=2 sw=2 sts=2 et:

This is an extension of the excellent work of peplin and casualjim (thanks), to add checking for XML error responses from Amazon and to add dual support for S3 and other protocols provided by the out-of-the-box RemoteFile (e.g. http(s)).

Note that the error checking is a bit of a hack. The problem is that in the event of an error (permissions or invalid S3 bucket name etc), the original implementation looked like it worked without raising an error, but the file that was downloaded actually contained an XML error message rather than the desired file contents. Therefore, this workaround basically parses the response file for an XML pattern:

fileContents.match(/<Error><Code>(.*)<\/Code><Message>(.*)<\/Message>.*<\/Error>/)

and might give false positives if the file you are downloading happens to be XML and contains that pattern. It could obviously be improved slightly by adding a match "starts with"..., but a better implmentation might involve looking at the response mime types or other headers.

It always gives a checksum didn't match target checksum (), updating

In the end a "DEBUG: Removing unused checksum cache file /var/chef/cache/checksu s/chef-file—tmp-chef-s3-file20120905-6387-1q3h1hh" always happens.

I've tested with other flavors of this gist, the same happens. The resource doesn't figure in the updated resource list, but the file seams to be transfered.

@poobury - Have you or @casualjim rolled this into a community cookbook?