opt-out / filter CPUCreditBalanceLow alarm

[slang25]

For non t2 EC2 instances, this alarm is always in the insufficient state

[tomhaigh]

Could we allow null as a threshold to disable the alarm? although we would need to be able to distinguish between an opt-out vs using the default threshold (where value isn't specified at all at any level).

[AnthonySteele]

Agreed, there should be a way to opt out form an alarm entirely.

[tomhaigh]

Would it be better to make this alarm opt-in? as using t2 isn't a default choice. Is it too late to change it now?

[tomhaigh]

Currently you can set threshold like this:

{
    "AlarmName": 400
}

This is shorthand for:

{
    "AlarmName": { 
         "Threshold": 400,
         // other options here like percentile, number of periods    
    }
}

proposal

Suggest we allow opt-out by adding another property:

{
    "AlarmName": { 
         "Enabled": false,
        // other options here like threshold, percentile, number of periods . not relevant here though
    }
}

(Some alarm types in future could have the Enabled property defaulted to false so that they become opt-in rather than opt-out.)

We can then make it easier to opt out by introducing another shorthand which would expand to the above:

{
    "AlarmName": false
}

The bit I don't really like about this is that the shorthand maps to two different properties depending on whether it's a bool or another type. But it does make it less painful to configure.

Thoughts @AnthonySteele @slang25 @andrewclowes ?

[tomhaigh]

Didn't get any feedback so have proceeded with PR implementing the above

[tomhaigh]

opt out was implemented in #128