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cloud engineer

AWS List of Auto Scaling Groups

Here’s a script to list Auto Scaling Groups from multiple AWS accounts. Accounts are in your AWS profiles.

#!/bin/bash
file='results-aws-asg.txt'
> $file
declare -a account=("default" "account-1" "account-2" "account-3" "account-4" "account-5")
declare -a region=("us-east-1" "us-east-2" "us-west-1" "us-west-2")
for i in "${account[@]}"
do
    echo '----------------------' >> $file
    echo 'Account: '$i >> $file
    for j in "${region[@]}"
    do
        echo 'Region: '$j >> $file
        aws autoscaling describe-auto-scaling-groups \
        --query "AutoScalingGroups[].[AutoScalingGroupName,LaunchConfigurationName]" \
        --profile $i \
        --region $j \
        --output text >> $file
    done
done

AWS Create Volume From Snapshot with Tags

Here’s another script that creates a volume from a snapshot, but also add the tags.

#!/bin/bash
read -p "server     : " server
read -p "volumeId   : " volume
read -p "snapshotId : " snapshot
read -p "region     : " region
read -p "zone       : " zone
read -p "profile    : " profile
# get tags
tags1=$(aws ec2 describe-volumes --volume-ids $volume --query 'Volumes[].Tags[]' --region $region --profile $profile)
# remove quotes
tags2=$(echo "$tags1" | tr -d '"')
# remove spaces
tags3=$(echo $tags2 | sed 's/ //g')
# replace : with =
tags4=$(echo $tags3 | sed 's/:/=/g')
# if empty value replace with quotes
tags5=$(echo $tags4 | sed 's/Value=}/Value=""}/g')
# create volume
aws ec2 create-volume \
--availability-zone $zone \
--encrypted \
--iops 3000 \
--volume-type gp3 \
--snapshot-id $snapshot \
--tag-specifications 'ResourceType=volume,Tags='$tags5'' \
--region $region \
--profile $profile

AWS Create Volume From Snapshot

Here’s a bash script that creates a volume from a snapshot in AWS.

#!/bin/bash
read -p "snapshotId : " snapshot
read -p "server     : " server
read -p "tag1       : " tag1
read -p "tag2       : " tag2
read -p "region     : " region
read -p "zone       : " zone
read -p "profile    : " profile
aws ec2 create-volume \
--availability-zone $zone \
--encrypted \
--iops 3000 \
--volume-type gp3 \
--snapshot-id $snapshot \
--tag-specifications "ResourceType=volume,Tags=[{Key=Name,Value="$server"},{Key=tag1,Value="$tag1"},{Key=tag2,Value="$tag2"}]" \
--region $region \
--profile $profile

Checking Nameservers

Handy little script to see if nameserver is on an array.

#!/bin/bash
declare -a servers=("127.0.0.53" "127.0.0.52" "127.0.0.51")
client=$(cat /etc/resolv.conf | grep nameserver)
for i in "${servers[@]}"
do
  if [[ $client =~ $i ]]
  then 
    using_unbound="true"
    break
  else
    using_unbound="false"
  fi
done
echo $using_unbound "|" $client

Windows Curl Command

If you have to download a file from the Internet on a Windows server, can certainly use the browser. But if the browser is rendering the file instead of downloading them, you may have to use the curl command which is already pre-installed on most Windows servers. Just open the command line. Here’s the the curl command to download a file.

curl.exe --output index.txt --url https://website.domain/index.txt

AWS List Account Aliases

Here’s how to list account aliases. I have four profiles in my credentials. I’m looping through all four and printing the aliases.

#!/bin/bash
file='results-aws-account-aliases.txt'
> $file
declare -a account=("default" "one" "two" "three")
for i in "${account[@]}"
do
    echo '----------------------' >> $file
    echo 'Account: '$i >> $file
    aws iam list-account-aliases \
    --profile $i 
done

Linux Screen

Just documenting the Linux Screen command.

Install screen first.

yum install screen
dnf install screen
apt install screen
zypper install screen

Start a new screen.

screen -S one
screen -S two
screen -S three

Detach from screen.

Ctrl+a+d

List active screens.

screen -ls 
There is a screen on:
        15575.one   (Detached)
        15581.two   (Detached)
        15593.three (Detached)
1 Socket in /var/run/screen/S-root.

Reattach to an existing screen.

screen -r one
screen -r two
screen -r three

If there’s only one active screen, you can run screen -r without the name.

screen -r

To exit or quit a screen, reattach and run exit.

screen -r three
# exit
[screen is terminating]