Class: Vector::Function::FlexibleDownScaling

Inherits:
Object
  • Object
show all
Includes:
HLogger
Defined in:
lib/vector/functions/flexible_down_scaling.rb

Instance Method Summary collapse

Methods included from HLogger

enable, #hlog, #hlog_ctx

Constructor Details

#initialize(options) ⇒ FlexibleDownScaling

Returns a new instance of FlexibleDownScaling.



8
9
10
11
12
13
 
# File 'lib/vector/functions/flexible_down_scaling.rb', line 8

def initialize(options)
  @cloudwatch = options[:cloudwatch]
  @up_down_cooldown = options[:up_down_cooldown]
  @down_down_cooldown = options[:down_down_cooldown]
  @max_sunk_cost = options[:max_sunk_cost]
end

Instance Method Details

#run_for(group, ps_check_procs) ⇒ Object 



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
79
80
81
82
83
84
85
 
# File 'lib/vector/functions/flexible_down_scaling.rb', line 15

def run_for(group, ps_check_procs)
  result = { :triggered => false }

  hlog_ctx("fds") do
    hlog_ctx("group:#{group.name}") do
      # don't check if no config was specified
      if @up_down_cooldown.nil? && @down_down_cooldown.nil?
        hlog("No cooldown periods specified, exiting")
        return result
      end

      # don't bother checking for a scaledown if desired capacity is
      # already at the minimum size...
      if group.desired_capacity == group.min_size
        hlog("Group is already at minimum size, exiting")
        return result
      end

      scaledown_policies = group.scaling_policies.select do |policy|
        policy.scaling_adjustment < 0
      end

      scaledown_policies.each do |policy|
        hlog_ctx("policy:#{policy.name}") do
          # TODO: support adjustment types other than ChangeInCapacity here
          if policy.adjustment_type == "ChangeInCapacity" &&
             ps_check_procs.any? {|ps_check_proc|
               ps_check_proc.call(group.desired_capacity + policy.scaling_adjustment) }
            hlog("Predictive scaleup would trigger a scaleup if group were shrunk")
            next
          end

          alarms = policy.alarms.keys.map do |alarm_name|
            @cloudwatch.alarms[alarm_name]
          end

          # only consider disabled alarms (enabled alarms will trigger
          # the policy automatically)
          disabled_alarms = alarms.select do |alarm|
            !alarm.enabled?
          end

          unless disabled_alarms.all? {|alarm| alarm.state_value == "ALARM" }
            hlog("Not all alarms are in ALARM state")
            next
          end

          unless outside_cooldown_period(group)
            hlog("Group is not outside the specified cooldown periods")
            next
          end

          unless has_eligible_scaledown_instance(group)
            hlog("Group does not have an instance eligible for scaledown due to max_sunk_cost")
            next
          end

          hlog("Executing policy")
          policy.execute(:honor_cooldown => true)

          result[:triggered] = true

          # no need to evaluate other scaledown policies
          return result
        end
      end
    end
  end

  result
end