Lambda container lifetime

handler.js

var startedAt = (new Date).toString();
var lastExecuted = null;

exports.ping = function(event, context, done) {
  lastExecutedCopy = lastExecuted;
  lastExecuted = (new Date).toString();
  done(null, {
    warm: !!lastExecutedCopy,
    startedAt: startedAt,
    last: lastExecutedCopy,
    now: lastExecuted
  });
};

test-timeouts.rb

require 'json'

def test(interval, desc)
  before = JSON.parse(`sls invoke -f ping`)
  sleep interval
  after = JSON.parse(`sls invoke -f ping`)
  outcome = after["warm"] ? "warm" : "cold"
  puts "Function was #{outcome} after #{desc}"
end

test(15 * 60, "fifteen minutes")