This is a bash script that creates a CloudFormation stack for a public certificate with DNS validation, based on input parameters provided as command line flags.

create-certificate-stack.sh

#!/bin/bash
# This is a bash script that creates a CloudFormation stack for a public certificate with DNS validation, 
# based on input parameters provided as command line flags.
# The script starts by defining the print_help function that displays the usage information for the script,
# along with the available command line flags.
# Next, the script uses the getopts command to parse the command line flags and store their values in variables
# (stack_name, csv_file, and domain_name). If any of the required flags are missing, the script will display 
# an error message and exit.
# The script then reads the contents of the CSV file into a bash array (subject_alternative_names), which 
# will be used to specify the SubjectAlternativeNames for the certificate.
# The script then converts the bash array into a string of comma-separated values (subject_alternative_names_string),
# which will be used to create the CloudFormation template file. The template file is created using the cat command,
# and includes the DomainName and SubjectAlternativeNames properties for the certificate.
# The script then uses the AWS CLI aws cloudformation create-stack command to create the CloudFormation stack,
# and waits for the stack creation to complete using the aws cloudformation wait stack-create-complete command.
# Finally, the script cleans up the CloudFormation template file using the rm command.

function print_help {
  echo "Usage: $0 [-s stack_name] [-c csv_file] [-d domain_name]"
  echo "  -s stack_name     Name of the CloudFormation stack to be created"
  echo "  -c csv_file       Name of the CSV file containing the SubjectAlternativeNames"
  echo "  -d domain_name    Domain name for the certificate"
  exit 1
}

# Get the command line flags
while getopts "s:c:d:" opt; do
  case ${opt} in
    s)
      stack_name="$OPTARG"
      ;;
    c)
      csv_file="$OPTARG"
      ;;
    d)
      domain_name="$OPTARG"
      ;;
    \?)
      echo "Invalid option: -$OPTARG"
      print_help
      ;;
    :)
      echo "Option -$OPTARG requires an argument."
      print_help
      ;;
  esac
done

# Check if the stack_name, csv_file, and domain_name flags were set
if [ -z "$stack_name" ] || [ -z "$csv_file" ] || [ -z "$domain_name" ]; then
  echo "ERROR: Missing required flags"
  print_help
fi

# Read the contents of the CSV file into a bash array
subject_alternative_names=()
while IFS=',' read -r line
do
  subject_alternative_names+=("$line")
done < "$csv_file"

# Convert the bash array into a string of comma-separated values
subject_alternative_names_string=""
for i in "${subject_alternative_names[@]}"; do
  subject_alternative_names_string="$subject_alternative_names_string'$i',"
done

# Remove the last comma
subject_alternative_names_string=${subject_alternative_names_string%?}

# Create the CloudFormation template file
template_file="template.yml"
cat > "$template_file" << EOL
---
AWSTemplateFormatVersion: '2010-09-09'
Resources:
  Certificate:
    Type: AWS::CertificateManager::Certificate
    Properties:
      DomainName: $domain_name
      SubjectAlternativeNames: [$subject_alternative_names_string]
      ValidationMethod: DNS
EOL

cat $template_file

# Create the CloudFormation stack
aws cloudformation create-stack \
  --stack-name "$stack_name" \
  --template-body "file://$template_file"

# Wait for the stack to complete
aws cloudformation wait stack-create-complete \
  --stack-name "$stack_name"

# Clean up the CloudFormation template file
rm "$template_file"