go-datadog-autoscaler

Autoscale AWS EC2 groups based on custom datadog metric queries.

Datadog config

Needs datadog API key and APP key.

AWS config

Needs aws credentials defined in the environment.

Scale UP/DOWN Intervals

You can now provide multiple intervals. The count value of the interval in which the metric query value falls will determine the change.

Imagine the following numberline:

-Inf --- 40 --- 50 --- 60<ScaleDOWN -- 'Stable Zone' -- ScaleUP>70 --- 80 --- 90 --- +Inf

If you want your metric to stay in the Stable Zone then you can provide iterative steps above or below it. The farther away it is from the Stable Zone, the more correction you can apply.

Assuming that the value is 95, you probably want to scale up by 5 to immediately relieve pressure but if it is 73, you might be ok scaling up by just 2. Same applies for the ScaleDOWN direction.

Using just a single element ScaleUP/ScaleDOWN interval will also work, with intervals defined as the example:

-Inf --- 60<ScaleDOWN -- 'Stable Zone' -- ScaleUP>90 --- +Inf

    # The "ScaleUp" operation (Required section)
    scaleUp:
        # Number of instances to add
      - count: 5
        # Trigger ScaleUp if the "Transformed" value is strictly > `threshold` value and < next higher threshold.
        threshold: 90
        # Honour cooldown
        cooldown: true
      - count: 3
        # Trigger ScaleUp if the "Transformed" value is strictly > `threshold` value and < next higher threshold.
        threshold: 80
        # Honour cooldown
        cooldown: true
      - count: 2
        # Trigger ScaleUp if the "Transformed" value is strictly > `threshold` value and < next higher threshold.
        threshold: 70
        # Honour cooldown
        cooldown: true

    # The "ScaleDown" operation (Required section)
    scaleDown:
        # Number of instances to remove from the autoscaling group
      - count: 1
        # Trigger ScaleDown if the "Transformed" value is strictly < `threshold` value and > next lower threshold.
        threshold: 60
        # Honour cooldown
        cooldown: true
      - count: 2
        # Trigger ScaleDown if the "Transformed" value is strictly < `threshold` value and > next lower threshold.
        threshold: 50
        # Honour cooldown
        cooldown: true
      - count: 4
        # Trigger ScaleDown if the "Transformed" value is strictly < `threshold` value and > next lower threshold.
        threshold: 40
        # Honour cooldown
        cooldown: true

##############################################################
# ScaleUP/DOWN thresholds are open intervals
#
# In the example above, consider the following metric values:
#
# 95 : Will scale UP by 5 for threshold 90 but below +Inf
# 87 : Will scale UP by 3 for threshold 80 but below 90
# 74 : Will scale UP by 2 for threshold 70 but below 80
#
# 65 : Will not have any effect
#
# 57 : Will scale DOWN by 1 for threshold 60 but above 50
# 45 : Will scale DOWN by 2 for threshold 50 but above 40
# 36 : Will scale DOWN by 4 for threshold 40 but above -Inf
##############################################################

TODO:

• Wire in "Honour Cooldown" when triggering autoscale. True by default