Class: Synapse::ServiceWatcher::BaseWatcher

Inherits:
Object
  • Object
show all
Includes:
Logging
Defined in:
lib/synapse/service_watcher/base.rb

Constant Summary collapse

LEADER_WARN_INTERVAL = 
30

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Logging

configure_logger_for, #log, logger_for

Constructor Details

#initialize(opts = {}, synapse) ⇒ BaseWatcher

Returns a new instance of BaseWatcher.



12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
 
# File 'lib/synapse/service_watcher/base.rb', line 12

def initialize(opts={}, synapse)
  super()

  @synapse = synapse
  @revision = 0

  # set required service parameters
  %w{name discovery}.each do |req|
    raise ArgumentError, "missing required option #{req}" unless opts[req]
  end

  @name = opts['name']
  @discovery = opts['discovery']

  # deprecated singular filter
  @singular_label_filter = @discovery['label_filter']
  unless @singular_label_filter.nil?
    log.warn "synapse: `label_filter` parameter is deprecated; use `label_filters` -- an array"
  end

  @label_filters = [@singular_label_filter, @discovery['label_filters']].flatten.compact

  @leader_election = opts['leader_election'] || false
  @leader_last_warn = Time.now - LEADER_WARN_INTERVAL

  @config_for_generator = Hash[
    @synapse.available_generators.collect do |generator_name, generator|
      watcher_provided_config = opts[generator_name] || {}
      normalized_generator_opts = generator.normalize_watcher_provided_config(
        @name, watcher_provided_config
      )
      [generator_name, normalized_generator_opts]
    end
  ]

  # set initial backends to default servers, if any
  @default_servers = opts['default_servers'] || []
  @backends = @default_servers

  @keep_default_servers = opts['keep_default_servers'] || false

  # If there are no default servers and a watcher reports no backends, then
  # use the previous backends that we already know about.
  @use_previous_backends = opts.fetch('use_previous_backends', true)

  # If backends discovered with this watcher lack ports or discovered
  # ports should be ignored, this option indicates that
  @backend_port_override = opts['backend_port_override'] || nil

  # For backwards compatability we support server_port_override
  # This will be removed in future versions
  if @backend_port_override.nil? && @config_for_generator['haproxy']
    @backend_port_override = @config_for_generator['haproxy']['server_port_override']
  end

  unless @backend_port_override.nil?
    unless @backend_port_override.to_s.match(/^\d+$/)
      raise ArgumentError, "Invalid backend_port_override value"
    end
  end

  # set a flag used to tell the watchers to exit
  # this is not used in every watcher
  @should_exit = false

  validate_discovery_opts
end

Instance Attribute Details

#config_for_generator ⇒ Object (readonly)

Returns the value of attribute config_for_generator.



10
11
12
 
# File 'lib/synapse/service_watcher/base.rb', line 10

def config_for_generator
  @config_for_generator
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



10
11
12
 
# File 'lib/synapse/service_watcher/base.rb', line 10

def name
  @name
end

#revision ⇒ Object (readonly)

Returns the value of attribute revision.



10
11
12
 
# File 'lib/synapse/service_watcher/base.rb', line 10

def revision
  @revision
end

Instance Method Details

#backends ⇒ Object 



102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
 
# File 'lib/synapse/service_watcher/base.rb', line 102

def backends
  filtered = backends_filtered_by_labels

  if @leader_election
    failure_warning = nil
    if filtered.empty?
      failure_warning = "synapse: service #{@name}: leader election failed: no backends to choose from"
    end

    all_backends_have_ids = filtered.all?{|b| b.key?('id') && b['id']}
    unless all_backends_have_ids
      failure_warning = "synapse: service #{@name}: leader election failed; not all backends include an id"
    end

    # no problems encountered, lets do the leader election
    if failure_warning.nil?
      smallest = filtered.sort_by{ |b| b['id']}.first
      log.debug "synapse: leader election chose one of #{filtered.count} backends " \
        "(#{smallest['host']}:#{smallest['port']} with id #{smallest['id']})"

      return [smallest]

    # we had some sort of problem, lets log about it
    elsif (Time.now - @leader_last_warn) > LEADER_WARN_INTERVAL
      @leader_last_warn = Time.now
      log.warn failure_warning
      return []
    end
  end

  return filtered
end

#haproxy ⇒ Object 



80
81
82
83
 
# File 'lib/synapse/service_watcher/base.rb', line 80

def haproxy
  log.warn "synapse: service watcher #{@name} accessing watcher.haproxy. This is DEPRECATED and will be removed in future iterations, use watcher.config_for_generator['haproxy'] instead."
  config_for_generator['haproxy']
end

#ping? ⇒ Boolean

this should be overridden to do a health check of the watcher

Returns:

  • (Boolean) 


98
99
100
 
# File 'lib/synapse/service_watcher/base.rb', line 98

def ping?
  true
end

#start ⇒ Object

this should be overridden to actually start your watcher



86
87
88
 
# File 'lib/synapse/service_watcher/base.rb', line 86

def start
  log.info "synapse: starting stub watcher; this means doing nothing at all!"
end

#stop ⇒ Object

this should be overridden to actually stop your watcher if necessary if you are running a thread, your loop should run ‘until @should_exit`



92
93
94
95
 
# File 'lib/synapse/service_watcher/base.rb', line 92

def stop
  log.info "synapse: stopping watcher #{self.name} using default stop handler"
  @should_exit = true
end