have 120 instances, which for this example translates to 235 volumes

add_tag.sh

#!/bin/bash
volCheck() {
    check="true"
    count=1
    # iterate through volumes, apply ec2 tags via tag()
    while [ "$check" = "true" ]; do   
        vol=$(echo $blockDevices | awk -F ' ' -v item=$count '{print $item}')
        if [ -n "$vol" ]; then #if vol exists, then call tag function
            echo "vol $vol exists"
            tag $vol
            ((count++))
        else
            check="false"
        fi
    done
}
# function that uses awscli to apply tags, is called form volCheck()
tag() {
    aws ec2 create-tags --region $REGION --resources $1 --tags Key=Location,Value=$LOCATION Key=Environment,Value=$ENVIRONMENT Key=Service,Value=$SERVICE Key=Role,Value=$ROLE Key=SubService,Value=VOL Key=Name,Value=$NAME
}
# grab ec2 instance metadata
INSTANCEID=$(curl -s http://111.111.111.254/latest/meta-data/instance-id)
REGION=$(curl -s http://111.111.111.254/latest/dynamic/instance-identity/document | jq -r .region)
INSTDATA=$(aws ec2 describe-instances --region $REGION --filters "Name=instance-id,Values=$INSTANCEID")

# specify tags 
TAGS=$(echo "$INSTDATA" | jq ".Reservations[0].Instances[0].Tags")
LOCATION=$(echo "$TAGS" | jq -r '.[] | select(.Key == "Location").Value')
ENVIRONMENT=$(echo "$TAGS" | jq -r '.[] | select(.Key == "Environment").Value')
SERVICE=$(echo "$TAGS" | jq -r '.[] | select(.Key == "Service").Value')
ROLE=$(echo "$TAGS" | jq -r '.[] | select(.Key == "Role").Value')
NAME=$(echo "$TAGS" | jq -r '.[] | select(.Key == "Name").Value')
# grab block devices from instance metadata
blockDevices=$(echo "$INSTDATA" | jq -r '.Reservations[0].Instances[0].BlockDeviceMappings[].Ebs.VolumeId')
# start tagging
volCheck
view raw

Let’s say you were tasked with ensuring that EC2 instance volumes have proper tags. Tags are used for many reasons including billing. You have 120 instances, which for this example translates to 235 volumes. This could be done manually but that sounds awful and impractical. If we take a manual approach we will have to tag more volumes every time an instance is created. Lets examine an on machine solution. We are going to look at a bash example. The AWS cli is required for these scripts to work.
So now we have some tagging automation and it works well. We have partially solved the problem for Linux and a PowerShell implementation can be very similar. If we put this into configuration management then we have a reliable hands off process. The main problem with the above example is that we have a solution that is dependent on a specific operating system. Let’s explore some other examples that we can plug and play anywhere.