Ec2 – Nextra

🧩 GOAL

✅ Find all EC2 instance IDs ✅ Fetch average CPU utilization for each ✅ Cover October and November (2 months) ✅ Output a clear list or table (instance ID + average CPU%)

🧠 Step-by-Step Solution

1️⃣ Get All EC2 Instance IDs

aws ec2 describe-instances \
  --region ap-south-1 \
  --query "Reservations[].Instances[].InstanceId" \
  --output text > instance_ids.txt

This will create a file instance_ids.txt with all instance IDs:

i-0123456789abcdef1
i-0a1234abcd5678
i-0ffedcba98765432
...

2️⃣ Loop Through Each Instance and Get CPU Average (for last 60 days)

#!/bin/bash
 
REGION="ap-south-1"
START_DATE=$(date -u -d '60 days ago' +%Y-%m-%dT%H:%M:%SZ)
END_DATE=$(date -u +%Y-%m-%dT%H:%M:%SZ)
 
echo "InstanceID,AverageCPU(%)" > ec2_cpu_report.csv
 
for instance in $(aws ec2 describe-instances \
    --region $REGION \
    --query "Reservations[].Instances[].InstanceId" \
    --output text); do
    
    avg_cpu=$(aws cloudwatch get-metric-statistics \
        --metric-name CPUUtilization \
        --start-time $START_DATE \
        --end-time $END_DATE \
        --period 86400 \
        --namespace AWS/EC2 \
        --statistics Average \
        --dimensions Name=InstanceId,Value=$instance \
        --region $REGION \
        --query "Datapoints[].Average" \
        --output text | awk '{ total += $1; count++ } END { if (count > 0) print total/count; else print 0 }')
    
    echo "$instance,${avg_cpu:-0}" >> ec2_cpu_report.csv
    echo "✔ Checked: $instance → Avg CPU = ${avg_cpu:-0}%"
done
 
echo "✅ Report generated: ec2_cpu_report.csv"

Save this as ec2_cpu_usage_report.sh, make it executable:

chmod +x ec2_cpu_usage_report.sh
./ec2_cpu_usage_report.sh

3️⃣ Output Example (`ec2_cpu_report.csv`):

Instance ID	Average CPU (%)
i-0123456789abcdef1	1.23
i-0a1234abcd5678	7.84
i-0ffedcba98765432	0.45

4️⃣ Interpretation:

Instances with <5% average CPU → likely idle / underutilized
Instances with >60–70% average CPU → potentially overloaded
You can use these insights for:
- Stopping idle ones
- Resizing (t3.xlarge → t3.medium, etc.)
- Applying Savings Plans

5️⃣ For October Only (Custom Date Range Example)

If you want October only, change:

START_DATE="2024-10-01T00:00:00Z"
END_DATE="2024-10-31T23:59:59Z"

And rerun the same script.

⚙️ Optional — More Metrics

You can easily expand this script to check:

NetworkIn / NetworkOut
DiskReadOps / DiskWriteOps
EBSIdleTime

For example:

--metric-name NetworkOut
--namespace AWS/EC2

💡 Best Practice:

Once you generate ec2_cpu_report.csv, sort it:

sort -t, -k2 -n ec2_cpu_report.csv

→ Gives you idle instances at the top (lowest CPU %).

Would you like me to modify this script so it:

Checks both CPU and Network usage (to detect truly idle EC2s), and
Generates a combined idle-instance summary (ready for cleanup)?

#!/bin/bash
# ---------------------------------------------------------------
#  EC2 Utilization Analyzer - Cost Optimization Helper
#  Finds Idle and Overutilized EC2 Instances (CPU + Network)
#  Region: ap-south-1
# ---------------------------------------------------------------
 
REGION="ap-south-1"
START_DATE=$(date -u -d '60 days ago' +%Y-%m-%dT%H:%M:%SZ)
END_DATE=$(date -u +%Y-%m-%dT%H:%M:%SZ)
OUTPUT_FILE="ec2_utilization_report.csv"
 
echo "InstanceID,Name,InstanceType,CPU_Avg(%),NetworkIn_Bytes,NetworkOut_Bytes,Status" > $OUTPUT_FILE
echo "🔍 Checking EC2 instances in region: $REGION ..."
 
INSTANCE_IDS=$(aws ec2 describe-instances \
  --region $REGION \
  --query "Reservations[].Instances[].InstanceId" \
  --output text)
 
for INSTANCE_ID in $INSTANCE_IDS; do
    # Get instance details
    read NAME TYPE <<< $(aws ec2 describe-instances \
      --region $REGION \
      --instance-ids $INSTANCE_ID \
      --query "Reservations[].Instances[].{Name:Tags[?Key=='Name']|[0].Value,Type:InstanceType}" \
      --output text)
 
    # --- Average CPU utilization ---
    CPU_AVG=$(aws cloudwatch get-metric-statistics \
      --metric-name CPUUtilization \
      --start-time $START_DATE \
      --end-time $END_DATE \
      --period 86400 \
      --namespace AWS/EC2 \
      --statistics Average \
      --dimensions Name=InstanceId,Value=$INSTANCE_ID \
      --region $REGION \
      --query "Datapoints[].Average" \
      --output text | awk '{ total += $1; count++ } END { if (count > 0) print total/count; else print 0 }')
 
    # --- Average Network In ---
    NET_IN=$(aws cloudwatch get-metric-statistics \
      --metric-name NetworkIn \
      --start-time $START_DATE \
      --end-time $END_DATE \
      --period 86400 \
      --namespace AWS/EC2 \
      --statistics Sum \
      --dimensions Name=InstanceId,Value=$INSTANCE_ID \
      --region $REGION \
      --query "Datapoints[].Sum" \
      --output text | awk '{ total += $1; count++ } END { if (count > 0) print total/count; else print 0 }')
 
    # --- Average Network Out ---
    NET_OUT=$(aws cloudwatch get-metric-statistics \
      --metric-name NetworkOut \
      --start-time $START_DATE \
      --end-time $END_DATE \
      --period 86400 \
      --namespace AWS/EC2 \
      --statistics Sum \
      --dimensions Name=InstanceId,Value=$INSTANCE_ID \
      --region $REGION \
      --query "Datapoints[].Sum" \
      --output text | awk '{ total += $1; count++ } END { if (count > 0) print total/count; else print 0 }')
 
    # --- Classification logic ---
    STATUS="NORMAL"
    if (( $(echo "$CPU_AVG < 5" | bc -l) )) && (( $(echo "($NET_IN + $NET_OUT) < 1000000" | bc -l) )); then
        STATUS="IDLE"
    elif (( $(echo "$CPU_AVG > 70" | bc -l) )); then
        STATUS="OVERUTILIZED"
    fi
 
    echo "$INSTANCE_ID,${NAME:-NoName},${TYPE:-Unknown},${CPU_AVG:-0},${NET_IN:-0},${NET_OUT:-0},$STATUS" >> $OUTPUT_FILE
    echo "✔ $INSTANCE_ID (${NAME:-NoName}) → CPU:${CPU_AVG:-0}% | NET_IN:${NET_IN:-0} | NET_OUT:${NET_OUT:-0} | $STATUS"
done
 
echo
echo "✅ Report generated: $OUTPUT_FILE"
echo "💡 Tip: Sort by 'Status' column (IDLE / OVERUTILIZED) to prioritize optimization."

Config and Ssl Gitfast