Repro script for librato. You can remove the VCR stuff it that helps; I added it to log the requests and responses.

librato-repro-script.rb

require 'librato/metrics'
require 'vcr'

VCR.configure do |vcr|
  vcr.hook_into :faraday
  vcr.cassette_library_dir = Dir.pwd
end

puts "Running on ruby version: #{RUBY_DESCRIPTION}"
puts "Using librato-metrics version: #{Librato::Metrics::VERSION}"

$metric_name = "qless.builder.failed-job-counts-all-klasses"

def create_client
  librato_email = ENV.fetch('EMAIL') { raise "Must pass [email protected]" }
  librato_token = ENV.fetch('API_TOKEN') { raise "Must pass API_TOKEN=someapitoken" }
  $client = Librato::Metrics::Client.new
  $client.authenticate(librato_email, librato_token)
end

def remove_all_metrics_to_produce_a_clean_slate
  puts "Deleting all prior metrics to create a clean slate"
  names = $client.list.map { |m| m.fetch("name") }
  $client.delete(*names) if names.any?
end

def submit_metrics
  puts "Submitting metric"
  queue = $client.new_queue(source: "test")
  queue.add($metric_name => 2)
  queue.submit
end

def fetch_metric
  puts "Sleeping for a bit to avoid eventual consistency issues"
  sleep 5
  puts "Fetching metric"
  raw = $client.fetch($metric_name, count: 2)
  puts raw.inspect
end

VCR.use_cassette("librato") do
  create_client
  remove_all_metrics_to_produce_a_clean_slate
  submit_metrics
  fetch_metric
end

librato.yml

---
http_interactions:
- request:
    method: get
    uri: https://metrics-api.librato.com/v1/metrics
    body:
      encoding: US-ASCII
      string: ''
    headers:
      User-Agent:
      - librato-metrics/1.0.4 (ruby; 1.9.3p327; x86_64-darwin11.4.0) direct-faraday/0.8.8
      Content-Type:
      - application/json
      Authorization:
      - Basic <redacted>
  response:
    status:
      code: 200
      message: 
    headers:
      content-type:
      - application/json;charset=utf-8
      date:
      - Tue, 03 Sep 2013 18:56:07 GMT
      server:
      - nginx/1.0.15
      status:
      - 200 OK
      content-length:
      - '66'
      connection:
      - Close
    body:
      encoding: US-ASCII
      string: ! '{"query":{"offset":0,"length":0,"found":0,"total":0},"metrics":[]}'
    http_version: 
  recorded_at: Tue, 03 Sep 2013 18:56:05 GMT
- request:
    method: post
    uri: https://metrics-api.librato.com/v1/metrics
    body:
      encoding: UTF-8
      string: ! '{"gauges":[{"name":"qless.builder.failed-job-counts-all-klasses","value":2,"measure_time":1378234566}],"source":"test"}'
    headers:
      User-Agent:
      - librato-metrics/1.0.4 (ruby; 1.9.3p327; x86_64-darwin11.4.0) direct-faraday/0.8.8
      Content-Type:
      - application/json
      Authorization:
      - Basic <redacted>
  response:
    status:
      code: 200
      message: 
    headers:
      content-type:
      - application/json;charset=utf-8
      date:
      - Tue, 03 Sep 2013 18:56:08 GMT
      server:
      - nginx/1.0.15
      status:
      - 200 OK
      content-length:
      - '0'
      connection:
      - Close
    body:
      encoding: US-ASCII
      string: ''
    http_version: 
  recorded_at: Tue, 03 Sep 2013 18:56:07 GMT
- request:
    method: get
    uri: https://metrics-api.librato.com/v1/metrics/qless.builder.failed-job-counts-all-klasses?count=2&resolution=1
    body:
      encoding: US-ASCII
      string: ''
    headers:
      User-Agent:
      - librato-metrics/1.0.4 (ruby; 1.9.3p327; x86_64-darwin11.4.0) direct-faraday/0.8.8
      Content-Type:
      - application/json
      Authorization:
      - Basic <redacted>
  response:
    status:
      code: 404
      message: 
    headers:
      content-type:
      - application/json
      date:
      - Tue, 03 Sep 2013 18:56:14 GMT
      server:
      - nginx/1.0.15
      status:
      - 404 Not Found
      content-length:
      - '36'
      connection:
      - Close
    body:
      encoding: US-ASCII
      string: ! '{"errors":{"request":["Not Found"]}}'
    http_version: 
  recorded_at: Tue, 03 Sep 2013 18:56:13 GMT
recorded_with: VCR 2.4.0

output

$ EMAIL=<redacted> API_TOKEN=<redacted> bundle exec ruby librato-repro-script.rb
Running on ruby version: ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-darwin11.4.0]
Using librato-metrics version: 1.0.4
Deleting all prior metrics to create a clean slate
Submitting metric
Sleeping for a bit to avoid eventual consistency issues
Fetching metric
/Users/myron/code/vanguard/bundle/ruby/1.9.1/gems/librato-metrics-1.0.4/lib/librato/metrics/middleware/expects_status.rb:15:in `on_complete': {:method=>:get, :body=>"{\"errors\":{\"request\":[\"Not Found\"]}}", :url=>#<URI::HTTPS:0x007fa5c23aad80 URL:https://metrics-api.librato.com/v1/metrics/qless.builder.failed-job-counts-all-klasses?count=2&resolution=1>, :request_headers=>{"User-Agent"=>"librato-metrics/1.0.4 (ruby; 1.9.3p327; x86_64-darwin11.4.0) direct-faraday/0.8.8", "Content-Type"=>"application/json", "Authorization"=>"Basic <redacted>=="}, :parallel_manager=>nil, :request=>{:open_timeout=>20, :timeout=>30, :proxy=>nil}, :ssl=>{}, :request_body=>nil, :status=>404, :response_headers=>{"content-type"=>"application/json", "date"=>"Tue, 03 Sep 2013 18:49:50 GMT", "server"=>"nginx/1.0.15", "status"=>"404 Not Found", "content-length"=>"36", "connection"=>"Close"}, :response=>#<Faraday::Response:0x007fa5c3472ca8 @env={...}, @on_complete_callbacks=[]>} (Librato::Metrics::NotFound)
	from /Users/myron/code/vanguard/bundle/ruby/1.9.1/gems/faraday-0.8.8/lib/faraday/response.rb:9:in `block in call'
	from /Users/myron/code/vanguard/bundle/ruby/1.9.1/gems/faraday-0.8.8/lib/faraday/response.rb:63:in `on_complete'
	from /Users/myron/code/vanguard/bundle/ruby/1.9.1/gems/faraday-0.8.8/lib/faraday/response.rb:8:in `call'
	from /Users/myron/code/vanguard/bundle/ruby/1.9.1/gems/librato-metrics-1.0.4/lib/librato/metrics/middleware/count_requests.rb:22:in `call'
	from /Users/myron/code/vanguard/bundle/ruby/1.9.1/gems/librato-metrics-1.0.4/lib/librato/metrics/middleware/retry.rb:17:in `call'
	from /Users/myron/code/vanguard/bundle/ruby/1.9.1/gems/librato-metrics-1.0.4/lib/librato/metrics/middleware/request_body.rb:11:in `call'
	from /Users/myron/code/vanguard/bundle/ruby/1.9.1/gems/faraday-0.8.8/lib/faraday/connection.rb:253:in `run_request'
	from /Users/myron/code/vanguard/bundle/ruby/1.9.1/gems/faraday-0.8.8/lib/faraday/connection.rb:106:in `get'
	from /Users/myron/code/vanguard/bundle/ruby/1.9.1/gems/librato-metrics-1.0.4/lib/librato/metrics/client.rb:160:in `fetch'
	from librato-repro-script.rb:31:in `fetch_metric'
	from librato-repro-script.rb:38:in `<main>'