Class: Nerve::ServiceWatcher

Inherits:
Object
  • Object
show all
Includes:
Logging, Utils
Defined in:
lib/nerve/service_watcher.rb

Instance Method Summary collapse

Methods included from Logging

configure_logger_for, #log, logger_for

Methods included from Utils

#safe_run

Constructor Details

#initialize(service = {}) ⇒ ServiceWatcher

Returns a new instance of ServiceWatcher.



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# File 'lib/nerve/service_watcher.rb', line 10

def initialize(service={})
  log.debug "nerve: creating service watcher object"

  # check that we have all of the required arguments
  %w{name instance_id host port}.each do |required|
    raise ArgumentError, "missing required argument #{required} for new service watcher" unless service[required]
  end

  @name = service['name']

  # configure the reporter, which we use for talking to zookeeper
  @reporter = Reporter.new_from_service(service)

  # instantiate the checks for this service
  @service_checks = []
  service['checks'] ||= []
  service['checks'].each do |check|
    check['type'] ||= "undefined"
    begin
      service_check_class = ServiceCheck::CHECKS[check['type']]
    rescue
      raise ArgumentError,
        "invalid service check type #{check['type']}; valid types: #{ServiceCheck::CHECKS.keys.join(',')}"
    end

    check['host'] ||= service['host']
    check['port'] ||= service['port']
    check['name'] ||= "#{@name} #{check['type']}-#{check['host']}:#{check['port']}"
    @service_checks << service_check_class.new(check)
  end

  # how often do we initiate service checks?
  @check_interval = service['check_interval'] || 0.5

  log.debug "nerve: created service watcher for #{@name} with #{@service_checks.size} checks"
end

Instance Method Details

#check? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/nerve/service_watcher.rb', line 83

def check?
  @service_checks.each do |check|
    return false unless check.up?
  end
  return true
end

#run ⇒ Object 



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# File 'lib/nerve/service_watcher.rb', line 47

def run()
  log.info "nerve: starting service watch #{@name}"

  @reporter.start()
  was_up = false

  until $EXIT
    @reporter.ping?

    # what is the status of the service?
    is_up = check?
    log.debug "nerve: current service status for #{@name} is #{is_up.inspect}"

    if is_up != was_up
      if is_up
        @reporter.report_up
        log.info "nerve: service #{@name} is now up"
      else
        @reporter.report_down
        log.warn "nerve: service #{@name} is now down"
      end
      was_up = is_up
    end

    # wait to run more checks
    sleep @check_interval
  end
rescue StandardError => e
  log.error "nerve: error in service watcher #{@name}: #{e.inspect}"
  raise e
ensure
  log.info "nerve: ending service watch #{@name}"
  $EXIT = true
  @reporter.stop
end