AWS Classroomnotes 27/Sep/2023

Activity2: Create a mysql rds instance

Exercises

• Correct the below script to use subnet_group_name and security_group_id

#!/bin/bash

# get_default_vpc_id()
# This function gets the default vpc id
function get_default_vpc_id() 
{
    vpc_id=$(aws ec2 describe-vpcs --filters "Name=is-default,Values=true" --query "Vpcs[].VpcId" --output text)
    echo $vpc_id
}

# get_subnet_ids(vpc_id)
# This function gets the subnet ids based on vpc's passed
function get_subnet_ids()
{
    default_vpc_id=$(get_default_vpc_id)
    vpc_id=${1:-$default_vpc_id}
    subnets=$(aws ec2 describe-subnets --filters "Name=vpc-id,Values=$vpc_id" --query "Subnets[].SubnetId" --output text)
    echo $subnets
}

# exists(string, substring)
# This function gets the subnet ids based on vpc's passed
function exists() 
{
    #STR='GNU/Linux is an operating system'
    #SUB='Linux'
    STR=$1
    SUB=$2
    if [[ "$STR" == *"$SUB"* ]]; then
        echo "Exists"
    else
        echo "NotExists"
    fi


}

subnet_group_name='custom'
subnet_ids=$(get_subnet_ids)

all_subnet_groups=$(aws rds describe-db-subnet-groups --query "DBSubnetGroups[].DBSubnetGroupName"  --output text)
echo $all_subnet_groups
exists_output=$(exists "$all_subnet_groups" $subnet_group_name)
if [[  $exists_output == "Exists" ]]; then
    echo "Subnet group already exists"
else
    echo "creating subnet group with ids ${subnet_ids}"
    aws rds create-db-subnet-group \
        --db-subnet-group-name $subnet_group_name \
        --db-subnet-group-description "created from cli" \
        --subnet-ids $subnet_ids \
        --query "DBSubnetGroup.DBSubnetGroupName"
    echo "Created subnet group"
fi

# create_security_group(name,description,vpc_id, port, whom)
# This function gets the subnet ids based on vpc's passed
function create_security_group()
{
    all_ip='0.0.0.0/0'
    default_vpc_id=$(get_default_vpc_id)
    name=${1:-rdssg}
    description=${2:-rdssg}
    vpc_id=${3:-$default_vpc_id}
    port=${4:-3306}
    whom=${5:-$all_ip}
    all_security_groups=$(aws ec2 describe-security-groups \
        --filters Name=vpc-id,Values=$vpc_id \
        --query "SecurityGroups[].GroupName" \
        --output text \
        )
    exists_output=$(exists "$all_security_groups" $name)

    if [[  $exists_output == "Exists" ]]; then
        echo "Security group already exists"
    else
        echo "creating security group "
        group_id=$(aws ec2 create-security-group \
            --description "$description" \
            --group-name $name \
            --vpc-id $vpc_id \
            --query "GroupId" \
            --output text
        )
        echo "Created subnet"

        aws ec2 authorize-security-group-ingress \
                --group-id $group_id \
                --protocol tcp \
                --port ${port} \
                --cidr ${whom}
        echo "create a security group ingress rule"
    fi


}

security_group_name="myrdssg"
description="open mysql to every one"
create_security_group $security_group_name "$description"

# create_security_group(identifier,size,engine, username, password, storage_size,subnet_group,security_group_id)
# This function gets the subnet ids based on vpc's passed
function create_rds()
{
    identifier=$1
    size=${2:-db.t2.micro}
    engine=${3:-mysql}
    username=${4:-qtdevops}
    password=${5:-qtdevopsqtdevops}
    storage_size=${6:-20}
    aws rds create-db-instance \
        --db-instance-identifier "${identifier}" \
        --db-instance-class "${size}" \
        --engine "${engine}" \
        --master-username "${username}" \
        --master-user-password "${password}" \
        --allocated-storage ${storage_size} \

}

create_rds "qtdevopsfromcli"

• Create a script which create an ec2 instance and displays ssh command
  • note: add a tag creator=script
• Create a script which delete all the ec2 instances created by scripts
  • Find all the ec2 instances with tag creator=script and delete them