Ruby script to take a snapshot of a Librato chart

take_librato_snapshot.rb

#!/usr/bin/env ruby

require 'faraday'
require 'json'

conn = Faraday.new(url: "https://metrics-api.librato.com/v1/") do |f|
  f.basic_auth ENV['LIBRATO_USER'], ENV['LIBRATO_TOKEN']
  # f.response :logger
  f.adapter Faraday.default_adapter
end

# Get list of spaces
resp = conn.get("spaces")
if resp.success?
  spaces = JSON(resp.body)['spaces']
else
  raise resp.inspect
end

# Get space in question
space_name = "Librato Agent"
space = spaces.detect {|s| s['name'] == space_name}
raise "space #{space_name} not found" unless space

# Get charts on the space
resp = conn.get("spaces/#{space['id']}/charts")
if resp.success?
  charts = JSON(resp.body)
else
  raise resp.inspect
end

# Find the chart by name
chart_name = "Memory Free"
chart = charts.detect {|c| c['name'] == chart_name}
raise "chart #{chart_name} not found" unless chart

# Set up snapshot params
chart_id = chart['id']
chart_type = 'line'
# chart_type = 'stacked'
source = "*"
duration = 3600
end_time = Time.now.to_i
# chart_type = 'stacked'
params = {
  subject: {
    chart: {
      id: chart_id,
      source: source,
      type: chart_type
    }
  },
  duration: duration,
  end_time: end_time
}

# Take the snapshot
resp = conn.post do |req|
  req.url "snapshots"
  req.headers["Content-Type"] = 'application/json'
  req.body = params.to_json
end
if resp.success?
  payload = JSON(resp.body)
  snapshot_href = payload['href']
  job_href = payload['job_href']
else
  raise resp.inspect
end

# Poll job until it is finished
max_poll_time = 30
slept = 0
job_state = nil
interval = 1

until job_state == 'complete' || slept > max_poll_time
  puts "Job state is: #{job_state}"
  puts "sleeping #{interval}..."
  sleep interval
  # poll job
  puts "Polling..."
  resp = conn.get(job_href)
  if resp.success?
    job = JSON(resp.body)
    job_state = job['state']
  else
    raise resp.inspect
  end
  slept += interval
end

puts "Spent #{slept} seconds getting chart id #{chart_id}"

if job_state == 'complete'
  # Retrieve finished snapshot with image URL
  resp = conn.get(snapshot_href)
  if resp.success?
    snapshot_data = JSON(resp.body)
    image_href = snapshot_data['image_href']
    puts "Chart: #{chart['name']}"
    puts "Snapshot URL:\n"
    puts image_href
  else
    raise resp.inspect
  end
else
  puts "Job status: #{job_state}"
end