This article shows how you can easily inject a generic key/value into Google Cloud Monitoring and set up alerts on it. I use it to alert on disk space, and now also low battery!
This morning I was in London, and I forgot my charger at home. With plenty of time but 🪫 little battery, I thought: hey! I need to have a way to predict when my battery is low! And I need to do it in a totally overkill way!
My battery was at 42%, which seemed a subtle indication my idea was worth blogging. Googling around, I found an article which gave me the tip on how to script my Mac’s battery (note this only works for a Macbook).
Ugly code here (hey! I’m in an airport with no charger, do you want Unit tests too?!?)
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#!/usr/bin/env ruby
# Note1. buridone is currently not used. It's for a more efficient use to extrapolate all info from a single file read.
# Note2. This does NOT work on M1. I've just fixed this in the github repo sakura. Find the updated 0.2 code there.
def processMacCapacity(buridone)
ret = {}
ret[:debug] = 'Will fill numerator and denominator until I nail it.'
ret[:capacity_pct] = 142 # clearlly wrong
# `ioreg -l -w0 | grep AppleRawMaxCapacity`.split
# => ["|", "|", "\"AppleRawMaxCapacity\"", "=", "4320"]
ret[:AppleRawMaxCapacity] = `ioreg -l -w0 | grep AppleRawMaxCapacity`.split[4].to_i
ret[:AppleRawCurrentCapacity] = `ioreg -l -w0 | grep AppleRawCurrentCapacity`.split[4].to_i
# => ["\"StateOfCharge\"=41"]
ret[:StateOfCharge] = `ioreg -l -w0 | grep BatteryData`.split(',').select{|e| e.match /StateOfCharge/ }[0].split('=')[1].to_i
ret[:AppleDesignCapacity] = `ioreg -l -w0 | grep BatteryData`.split(',').select{|e| e.match /DesignCapacity/ }[0].split('=')[1].to_i
# derived values..
# this should be your battery life i guess?x
ret[:BatteryCapacityPercent] = ret[:AppleRawCurrentCapacity]*100.0/ret[:AppleRawMaxCapacity]
ret[:battery_health] = ret[:AppleRawMaxCapacity]*100.0/ret[:AppleDesignCapacity]
return ret
end
def real_program
capacity_hash = processMacCapacity(`ioreg -l -w0 | grep Capacity`)
deb "capacity_hash: '''#{white capacity_hash}'''"
if $DEBUG
capacity_hash.each{|k,v|
puts "[DEB] #{k}:\t#{v}"
}
end
puts "1. 🔋 BatteryLife % 🔌🪫: #{capacity_hash[:BatteryCapacityPercent].round(2)}"
puts "2. 🔋 BatteryHealth % 🛟: #{capacity_hash[:battery_health].round(2)}"
end
def main(filename)
deb "I'm called by #{white filename}"
init # Enable this to have command line parsing capabilities!
real_program
end
main(__FILE__)
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I know, I call the same command 10 times and I could cache it. This is for the next iteration!
The best part of this is, not only I get my battery life, it also gives me my battery durability — so when I need to change battery. Woohoo!
There you go, let’s try it out, let me just remove the cable so you dont get a boring 100%.
TODO(ricc): finish
See article on Medium