AWS Cloudwatch - usage questions

• Do custom metrics refer when I use cloudwatch agent or scripting? Yes
• By default many metrics are available for use, I understand with data ingested but this does not generate charges, right? No charges for default metrics unless you need detailed metrics not available by default eg. EC2 detailed monitoring
• Are metrics charged only when I add metrics to alarms?, or per example if I install cloudwatch agent, the metrics that appear are charged as available in that moment, or only if I use within an alarm? Metrics and alarms are chargeable separately, independent of each other. So metrics are charged when you start sending it to Cloudwatch and alarms are charged for when created
• If I have multiple alarms with different thresholds for the same metric and instance. Per example; I need to monitor an EC2 CPU, so I create 03 alarms: warning (93%), critical (95%), fatal (98%). The cpu metric is charged 03 times or only one? *You'll be charged for three alarms *
• How can I create one alarm with multiple metric for a server, or one metric for multiple servers? Alarms are per resource and per metric. If you need averaging across resources of the same type (eg. EC2), you might look for relevant metrics at ALB, ASG or target group level; but this wont give you individual alarms
• If I have one metric in one alarm, the cost is for one metric and one alarm, or only for one of them? *Cost is for metric (if custom) and alarm. *

You can refer to https://aws.amazon.com/cloudwatch/pricing/ for more examples

--Syd