Module: ElbPing::CLI

Defined in:
lib/elbping/cli.rb

Overview

Setup and initialization for running as a CLI app happens here. Specifically, on load it will read in environment variables and set up default values for the app.

Constant Summary collapse

OPTIONS =

Set up default options

{}
PARSER =

Build parser for command line options

OptionParser.new do |opts|
  opts.banner = "Usage: #{$0} [options] <elb uri>"

  opts.on("-L LENGTH", "--verb-length LENGTH", Integer,
    "Use verb LENGTH characters long (default: #{OPTIONS[:verb_len]})") do |n|
    OPTIONS[:verb_len] = n
  end
  opts.on("-W SECONDS", "--timeout SECONDS", Integer,
    "Use timeout of SECONDS for HTTP requests (default: #{OPTIONS[:timeout]})") do |n|
    OPTIONS[:timeout] = n
  end
  opts.on("-w SECONDS", "--wait SECONDS", Integer,
    "Wait SECONDS between pings (default: #{OPTIONS[:wait]})") do |n|
    OPTIONS[:wait] = n
  end
  opts.on("-c COUNT", "--count COUNT", Integer,
    "Ping each node COUNT times (default: #{OPTIONS[:count]})") do |n|
    OPTIONS[:count] = n
  end
end

Class Method Summary collapse

Class Method Details

.main ⇒ Object

Main entry point of the program. Specifically, this method will:

  • Parse and validate command line arguments

  • Use the ‘ElbPing::Resolver` to discover ELB nodes

  • Use the ‘ElbPing::HttpPinger` to ping ELB nodes

  • Track the statistics for these pings

  • And, finally, use call upon ‘ElbPing::Display` methods to output to stdout



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# File 'lib/elbping/cli.rb', line 59

def self.main
  # Catch ctrl-c
  run = true
  trap("SIGINT") {
    run = false
  }

  ##
  # Parse and validate command line arguments
  PARSER.parse!(ARGV) rescue usage

  if ARGV.size < 1
    usage
  end

  unless ARGV[0] =~ URI::regexp
    ElbPing::Display.error "ELB URI does not seem valid"
    usage
  end

  elb_uri_s = ARGV[0]
  elb_uri = URI.parse(elb_uri_s)

  ##
  # Discover ELB nodes
  #
  # TODO: Perhaps some retry logic
  begin
    nodes = ElbPing::Resolver.find_elb_nodes elb_uri.host
  rescue StandardError => e
    ElbPing::Display.error "Unable to query DNS for #{elb_uri.host}"
    ElbPing::Display.debug e
    exit(false)
  end

  if nodes.size < 1
    ElbPing::Display.error "Could not find any ELB nodes, no pings sent"
    exit(false)
  end

  ##
  # Set up summary objects for stats tracking of latency and loss
  stats = ElbPing::Stats.new
  nodes.each { |node| stats.add_node node }

  ##
  # Run the main loop of the program
  iteration = 0
  while run && (OPTIONS[:count] < 1 || iteration < OPTIONS[:count])

    sleep OPTIONS[:wait] if iteration > 0

    ##
    # Ping each node while tracking requests, responses, and latencies
    nodes.map { |node|
      break if not run

      status = ElbPing::HttpPinger.ping_node(node,
        elb_uri.port,
        (elb_uri.path == "") ? "/" : elb_uri.path,
        (elb_uri.scheme == 'https'),
        OPTIONS[:verb_len], OPTIONS[:timeout])

      # Display the response from the ping
      ElbPing::Display.response status

      # Register stats
      stats.register status
    }
    iteration += 1
  end
  # Display the stats summary
  ElbPing::Display.summary stats
end

.usage ⇒ Object

Displays usage



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# File 'lib/elbping/cli.rb', line 46

def self.usage
  ElbPing::Display.out PARSER.help
  exit(false)
end