calculate SLA from Cloudwatch metric

CalcwSLA.sh

#!/bin/bash

INSTANCE_ID="i-0axxxxxxxxxx"
NAMESPACE="AWS/EC2"
METRIC_NAME="StatusCheckFailed_Instance"
START_TIME=$(date -u -d '30 day ago' +%Y-%m-%dT%H:%M:%SZ)
END_TIME=$(date -u +%Y-%m-%dT%H:%M:%SZ)
AWS_PROFILE=my_profile

# Retrieve the metric data
DATA=$(aws cloudwatch get-metric-data \
  --metric-data-queries '[
    {
      "Id": "m1",
      "MetricStat": {
        "Metric": {
          "Namespace": "'"$NAMESPACE"'",
          "MetricName": "'"$METRIC_NAME"'",
          "Dimensions": [
            {
              "Name": "InstanceId",
              "Value": "'"$INSTANCE_ID"'"
            }
          ]
        },
        "Period": 300,
        "Stat": "Maximum"
      },
      "ReturnData": true
    }
  ]' \
  --start-time "$START_TIME" \
  --end-time "$END_TIME" \
  --scan-by 'TimestampDescending' \
  --query 'MetricDataResults[0].Values[]' \
  --profile "$AWS_PROFILE" \
  --output 'text')

# Calculate the SLA percentage
SUM=$(echo $DATA | tr ' ' '\n' | awk '{sum += $1} END {print sum}')
#echo "SUM=$SUM"
TOTAL=$(echo $DATA | tr ' ' '\n' | wc -l)
#echo "TOTAL=$TOTAL"
SLA=$(echo "scale=2; (100 * ($SUM * 5 - 43200)) / 43200" | bc | awk '{print ($1 < 0) ? -$1 : $1}' )
echo "SLA=$SLA"

# Print the result
echo "SLA for $METRIC_NAME on instance $INSTANCE_ID over the last 30 days: $SLA%"

Replace

INSTANCE_ID
AWS_PROFILE

to your aws

(echo "scale=2; (100 * ($SUM * 5 - 43200)) / 43200" | bc | awk '{print ($1 < 0) ? -$1 : $1}' )

$SUM = sum datapoint results
Example $SUM = 16

This command will perform the following sequence of calculations:

1. Multiply 16 and 5 to get 80.
2. Subtract 43200 from 80 to get -43120.
3. Multiply -43120 and 100 to get -4312000.
4. Divide -4312000 by 43200 to get -99.81481....
5. The absolute value of -99.81481... is 99.81481....
6. bc rounds the result to a scale of 2, which gives the final output of 99.81.

Therefore, the bc command will calculate the sequence of (16 * 5), 43200 - result from 1, (result from 2) * 100, and (result from 3) / 43200 as 99.81.