Use CreateKeyPair with an AWS SDK or CLI

    /// <summary>
    /// Create an Amazon EC2 key pair with a specified name.
    /// </summary>
    /// <param name="keyPairName">The name for the new key pair.</param>
    /// <returns>The Amazon EC2 key pair created.</returns>
    public async Task<KeyPair?> CreateKeyPair(string keyPairName)
    {
        try
        {
            var request = new CreateKeyPairRequest { KeyName = keyPairName, };

            var response = await _amazonEC2.CreateKeyPairAsync(request);

            var kp = response.KeyPair;
            // Return the key pair so it can be saved if needed.

            // Wait until the key pair exists.
            int retries = 5;
            while (retries-- > 0)
            {
                Console.WriteLine($"Checking for new KeyPair {keyPairName}...");
                var keyPairs = await DescribeKeyPairs(keyPairName);
                if (keyPairs.Any())
                {
                    return kp;
                }

                Thread.Sleep(5000);
                retries--;
            }
            _logger.LogError($"Unable to find newly created KeyPair {keyPairName}.");
            throw new DoesNotExistException("KeyPair not found");
        }
        catch (AmazonEC2Exception ec2Exception)
        {
            if (ec2Exception.ErrorCode == "InvalidKeyPair.Duplicate")
            {
                _logger.LogError(
                    $"A key pair called {keyPairName} already exists.");
            }

            throw;
        }
        catch (Exception ex)
        {
            _logger.LogError(
                $"An error occurred while creating the key pair.: {ex.Message}");
            throw;
        }
    }

    /// <summary>
    /// Save KeyPair information to a temporary file.
    /// </summary>
    /// <param name="keyPair">The name of the key pair.</param>
    /// <returns>The full path to the temporary file.</returns>
    public string SaveKeyPair(KeyPair keyPair)
    {
        var tempPath = Path.GetTempPath();
        var tempFileName = $"{tempPath}\\{Path.GetRandomFileName()}";
        var pemFileName = Path.ChangeExtension(tempFileName, "pem");

        // Save the key pair to a file in a temporary folder.
        using var stream = new FileStream(pemFileName, FileMode.Create);
        using var writer = new StreamWriter(stream);
        writer.WriteLine(keyPair.KeyMaterial);

        return pemFileName;
    }

###############################################################################
# function ec2_create_keypair
#
# This function creates an Amazon Elastic Compute Cloud (Amazon EC2) ED25519 or 2048-bit RSA key pair
# and writes it to a file.
#
# Parameters:
#       -n key_pair_name - A key pair name.
#       -f file_path - File to store the key pair.
#
# And:
#       0 - If successful.
#       1 - If it fails.
###############################################################################
function ec2_create_keypair() {
  local key_pair_name file_path response
  local option OPTARG # Required to use getopts command in a function.

  # bashsupport disable=BP5008
  function usage() {
    echo "function ec2_create_keypair"
    echo "Creates an Amazon Elastic Compute Cloud (Amazon EC2) ED25519 or 2048-bit RSA key pair"
    echo " and writes it to a file."
    echo "  -n key_pair_name - A key pair name."
    echo "  -f file_path - File to store the key pair."
    echo ""
  }

  # Retrieve the calling parameters.
  while getopts "n:f:h" option; do
    case "${option}" in
      n) key_pair_name="${OPTARG}" ;;
      f) file_path="${OPTARG}" ;;
      h)
        usage
        return 0
        ;;
      \?)
        echo "Invalid parameter"
        usage
        return 1
        ;;
    esac
  done
  export OPTIND=1

  if [[ -z "$key_pair_name" ]]; then
    errecho "ERROR: You must provide a key name with the -n parameter."
    usage
    return 1
  fi

  if [[ -z "$file_path" ]]; then
    errecho "ERROR: You must provide a file path with the -f parameter."
    usage
    return 1
  fi

  response=$(aws ec2 create-key-pair \
    --key-name "$key_pair_name" \
    --query 'KeyMaterial' \
    --output text) || {
    aws_cli_error_log ${?}
    errecho "ERROR: AWS reports create-access-key operation failed.$response"
    return 1
  }

  if [[ -n "$file_path" ]]; then
    echo "$response" >"$file_path"
  fi

  return 0
}

The utility functions used in this example.

###############################################################################
# function errecho
#
# This function outputs everything sent to it to STDERR (standard error output).
###############################################################################
function errecho() {
  printf "%s\n" "$*" 1>&2
}

##############################################################################
# function aws_cli_error_log()
#
# This function is used to log the error messages from the AWS CLI.
#
# The function expects the following argument:
#         $1 - The error code returned by the AWS CLI.
#
#  Returns:
#          0: - Success.
#
##############################################################################
function aws_cli_error_log() {
  local err_code=$1
  errecho "Error code : $err_code"
  if [ "$err_code" == 1 ]; then
    errecho "  One or more S3 transfers failed."
  elif [ "$err_code" == 2 ]; then
    errecho "  Command line failed to parse."
  elif [ "$err_code" == 130 ]; then
    errecho "  Process received SIGINT."
  elif [ "$err_code" == 252 ]; then
    errecho "  Command syntax invalid."
  elif [ "$err_code" == 253 ]; then
    errecho "  The system environment or configuration was invalid."
  elif [ "$err_code" == 254 ]; then
    errecho "  The service returned an error."
  elif [ "$err_code" == 255 ]; then
    errecho "  255 is a catch-all error."
  fi

  return 0
}

//! Create an Amazon Elastic Compute Cloud (Amazon EC2) instance key pair.
/*!
  \param keyPairName: A name for a key pair.
  \param keyFilePath: File path where the credentials are stored. Ignored if it is an empty string;
  \param clientConfiguration: AWS client configuration.
  \return bool: Function succeeded.
 */
bool AwsDoc::EC2::createKeyPair(const Aws::String &keyPairName, const Aws::String &keyFilePath,
                                const Aws::Client::ClientConfiguration &clientConfiguration) {
    Aws::EC2::EC2Client ec2Client(clientConfiguration);
    Aws::EC2::Model::CreateKeyPairRequest request;
    request.SetKeyName(keyPairName);

    Aws::EC2::Model::CreateKeyPairOutcome outcome = ec2Client.CreateKeyPair(request);
    if (!outcome.IsSuccess()) {
        std::cerr << "Failed to create key pair - "  << keyPairName << ". " <<
                  outcome.GetError().GetMessage() << std::endl;
    } else {
        std::cout << "Successfully created key pair named " <<
                  keyPairName << std::endl;
        if (!keyFilePath.empty()) {
            std::ofstream keyFile(keyFilePath.c_str());
            keyFile << outcome.GetResult().GetKeyMaterial();
            keyFile.close();
            std::cout << "Keys written to the file " <<
                      keyFilePath << std::endl;
        }

    }

    return outcome.IsSuccess();

}

To create a key pair

This example creates a key pair named MyKeyPair.

Command:

aws ec2 create-key-pair --key-name MyKeyPair

The output is an ASCII version of the private key and key fingerprint. You need to save the key to a file.

For more information, see Using Key Pairs in the AWS Command Line Interface User Guide.

    /**
     * Creates a new key pair asynchronously.
     *
     * @param keyName the name of the key pair to create
     * @param fileName the name of the file to write the key material to
     * @return a {@link CompletableFuture} that represents the asynchronous operation
     *         of creating the key pair and writing the key material to a file
     */
    public CompletableFuture<CreateKeyPairResponse> createKeyPairAsync(String keyName, String fileName) {
        CreateKeyPairRequest request = CreateKeyPairRequest.builder()
            .keyName(keyName)
            .build();

        CompletableFuture<CreateKeyPairResponse> responseFuture = getAsyncClient().createKeyPair(request);
        responseFuture.whenComplete((response, exception) -> {
            if (response != null) {
                try {
                    BufferedWriter writer = new BufferedWriter(new FileWriter(fileName));
                    writer.write(response.keyMaterial());
                    writer.close();
                } catch (IOException e) {
                    throw new RuntimeException("Failed to write key material to file: " + e.getMessage(), e);
                }
            } else {
                throw new RuntimeException("Failed to create key pair: " + exception.getMessage(), exception);
            }
        });

        return responseFuture;
    }

import { CreateKeyPairCommand, EC2Client } from "@aws-sdk/client-ec2";

/**
 * Creates an ED25519 or 2048-bit RSA key pair with the specified name and in the specified PEM or PPK format.
 * Amazon EC2 stores the public key and displays the private key for you to save to a file.
 * @param {{ keyName: string }} options
 */
export const main = async ({ keyName }) => {
  const client = new EC2Client({});
  const command = new CreateKeyPairCommand({
    KeyName: keyName,
  });

  try {
    const { KeyMaterial, KeyName } = await client.send(command);
    console.log(KeyName);
    console.log(KeyMaterial);
  } catch (caught) {
    if (caught instanceof Error && caught.name === "InvalidKeyPair.Duplicate") {
      console.warn(`${caught.message}. Try another key name.`);
    } else {
      throw caught;
    }
  }
};

suspend fun createEC2KeyPair(keyNameVal: String) {
    val request =
        CreateKeyPairRequest {
            keyName = keyNameVal
        }

    Ec2Client { region = "us-west-2" }.use { ec2 ->
        val response = ec2.createKeyPair(request)
        println("The key ID is ${response.keyPairId}")
    }
}

Example 1: This example creates a key pair and captures the PEM-encoded RSA private key in a file with the specified name. When you are using PowerShell, the encoding must be set to ascii to generate a valid key. For more information, see Create, Display, and Delete Amazon EC2 Key Pairs (https://docs.aws.amazon.com/cli/latest/userguide/cli-services-ec2-keypairs.html) in the AWS Command Line Interface User Guide.

(New-EC2KeyPair -KeyName "my-key-pair").KeyMaterial | Out-File -Encoding ascii -FilePath C:\path\my-key-pair.pem

class KeyPairWrapper:
    """
    Encapsulates Amazon Elastic Compute Cloud (Amazon EC2) key pair actions.
    This class provides methods to create, list, and delete EC2 key pairs.
    """

    def __init__(
        self,
        ec2_client: boto3.client,
        key_file_dir: Union[tempfile.TemporaryDirectory, str],
        key_pair: Optional[dict] = None,
    ):
        """
        Initializes the KeyPairWrapper with the specified EC2 client, key file directory,
        and an optional key pair.

        :param ec2_client: A Boto3 Amazon EC2 client. This client provides low-level
                           access to AWS EC2 services.
        :param key_file_dir: The folder where the private key information is stored.
                             This should be a secure folder.
        :param key_pair: A dictionary representing the Boto3 KeyPair object.
                         This is a high-level object that wraps key pair actions. Optional.
        """
        self.ec2_client = ec2_client
        self.key_pair = key_pair
        self.key_file_path: Optional[str] = None
        self.key_file_dir = key_file_dir

    @classmethod
    def from_client(cls) -> "KeyPairWrapper":
        """
        Class method to create an instance of KeyPairWrapper using a new EC2 client
        and a temporary directory for storing key files.

        :return: An instance of KeyPairWrapper.
        """
        ec2_client = boto3.client("ec2")
        return cls(ec2_client, tempfile.TemporaryDirectory())


    def create(self, key_name: str) -> dict:
        """
        Creates a key pair that can be used to securely connect to an EC2 instance.
        The returned key pair contains private key information that cannot be retrieved
        again. The private key data is stored as a .pem file.

        :param key_name: The name of the key pair to create.
        :return: A dictionary representing the Boto3 KeyPair object that represents the newly created key pair.
        :raises ClientError: If there is an error in creating the key pair, for example, if a key pair with the same name already exists.
        """
        try:
            response = self.ec2_client.create_key_pair(KeyName=key_name)
            self.key_pair = response
            self.key_file_path = os.path.join(
                self.key_file_dir.name, f"{self.key_pair['KeyName']}.pem"
            )
            with open(self.key_file_path, "w") as key_file:
                key_file.write(self.key_pair["KeyMaterial"])
        except ClientError as err:
            if err.response["Error"]["Code"] == "InvalidKeyPair.Duplicate":
                logger.error(
                    f"A key pair called {key_name} already exists. "
                    "Please choose a different name for your key pair "
                    "or delete the existing key pair before creating."
                )
            raise
        else:
            return self.key_pair

# This code example does the following:
# 1. Creates a key pair in Amazon Elastic Compute Cloud (Amazon EC2).
# 2. Displays information about available key pairs.
# 3. Deletes the key pair.

require 'aws-sdk-ec2'

# @param ec2_client [Aws::EC2::Client] An initialized EC2 client.
# @param key_pair_name [String] The name for the key pair and private
#   key file.
# @return [Boolean] true if the key pair and private key file were
#   created; otherwise, false.
# @example
#   exit 1 unless key_pair_created?(
#     Aws::EC2::Client.new(region: 'us-west-2'),
#     'my-key-pair'
#   )
def key_pair_created?(ec2_client, key_pair_name)
  key_pair = ec2_client.create_key_pair(key_name: key_pair_name)
  puts "Created key pair '#{key_pair.key_name}' with fingerprint " \
    "'#{key_pair.key_fingerprint}' and ID '#{key_pair.key_pair_id}'."
  filename = File.join(Dir.home, "#{key_pair_name}.pem")
  File.open(filename, 'w') { |file| file.write(key_pair.key_material) }
  puts "Private key file saved locally as '#{filename}'."
  true
rescue Aws::EC2::Errors::InvalidKeyPairDuplicate
  puts "Error creating key pair: a key pair named '#{key_pair_name}' " \
    'already exists.'
  false
rescue StandardError => e
  puts "Error creating key pair or saving private key file: #{e.message}"
  false
end

# Displays information about available key pairs in
# Amazon Elastic Compute Cloud (Amazon EC2).
#
# @param ec2_client [Aws::EC2::Client] An initialized EC2 client.
# @example
#   describe_key_pairs(Aws::EC2::Client.new(region: 'us-west-2'))
def describe_key_pairs(ec2_client)
  result = ec2_client.describe_key_pairs
  if result.key_pairs.count.zero?
    puts 'No key pairs found.'
  else
    puts 'Key pair names:'
    result.key_pairs.each do |key_pair|
      puts key_pair.key_name
    end
  end
rescue StandardError => e
  puts "Error getting information about key pairs: #{e.message}"
end

# Deletes a key pair in Amazon Elastic Compute Cloud (Amazon EC2).
#
# Prerequisites:
#
# - The key pair to delete.
#
# @param ec2_client [Aws::EC2::Client] An initialized EC2 client.
# @param key_pair_name [String] The name of the key pair to delete.
# @return [Boolean] true if the key pair was deleted; otherwise, false.
# @example
#   exit 1 unless key_pair_deleted?(
#     Aws::EC2::Client.new(region: 'us-west-2'),
#     'my-key-pair'
#   )
def key_pair_deleted?(ec2_client, key_pair_name)
  ec2_client.delete_key_pair(key_name: key_pair_name)
  true
rescue StandardError => e
  puts "Error deleting key pair: #{e.message}"
  false
end

# Example usage:
def run_me
  key_pair_name = ''
  region = ''
  # Print usage information and then stop.
  if ARGV[0] == '--help' || ARGV[0] == '-h'
    puts 'Usage:   ruby ec2-ruby-example-key-pairs.rb KEY_PAIR_NAME REGION'
    puts 'Example: ruby ec2-ruby-example-key-pairs.rb my-key-pair us-west-2'
    exit 1
  # If no values are specified at the command prompt, use these default values.
  # Replace us-west-2 with the AWS Region you're using for Amazon EC2.
  elsif ARGV.count.zero?
    key_pair_name = 'my-key-pair'
    region = 'us-west-2'
  # Otherwise, use the values as specified at the command prompt.
  else
    key_pair_name = ARGV[0]
    region = ARGV[1]
  end

  ec2_client = Aws::EC2::Client.new(region: region)

  puts 'Displaying existing key pair names before creating this key pair...'
  describe_key_pairs(ec2_client)

  puts '-' * 10
  puts 'Creating key pair...'
  unless key_pair_created?(ec2_client, key_pair_name)
    puts 'Stopping program.'
    exit 1
  end

  puts '-' * 10
  puts 'Displaying existing key pair names after creating this key pair...'
  describe_key_pairs(ec2_client)

  puts '-' * 10
  puts 'Deleting key pair...'
  unless key_pair_deleted?(ec2_client, key_pair_name)
    puts 'Stopping program. You must delete the key pair yourself.'
    exit 1
  end
  puts 'Key pair deleted.'

  puts '-' * 10
  puts 'Now that the key pair is deleted, ' \
    'also deleting the related private key pair file...'
  filename = File.join(Dir.home, "#{key_pair_name}.pem")
  File.delete(filename)
  if File.exist?(filename)
    puts "Could not delete file at '#{filename}'. You must delete it yourself."
  else
    puts 'File deleted.'
  end

  puts '-' * 10
  puts 'Displaying existing key pair names after deleting this key pair...'
  describe_key_pairs(ec2_client)
end

run_me if $PROGRAM_NAME == __FILE__

Rust implementation that calls the EC2 Client's create_key_pair and extracts the returned material.

    pub async fn create_key_pair(&self, name: String) -> Result<(KeyPairInfo, String), EC2Error> {
        tracing::info!("Creating key pair {name}");
        let output = self.client.create_key_pair().key_name(name).send().await?;
        let info = KeyPairInfo::builder()
            .set_key_name(output.key_name)
            .set_key_fingerprint(output.key_fingerprint)
            .set_key_pair_id(output.key_pair_id)
            .build();
        let material = output
            .key_material
            .ok_or_else(|| EC2Error::new("Create Key Pair has no key material"))?;
        Ok((info, material))
    }

A function that calls the create_key impl and securely saves the PEM private key.

    /// Creates a key pair that can be used to securely connect to an EC2 instance.
    /// The returned key pair contains private key information that cannot be retrieved
    /// again. The private key data is stored as a .pem file.
    ///
    /// :param key_name: The name of the key pair to create.
    pub async fn create(
        &mut self,
        ec2: &EC2,
        util: &Util,
        key_name: String,
    ) -> Result<KeyPairInfo, EC2Error> {
        let (key_pair, material) = ec2.create_key_pair(key_name.clone()).await.map_err(|e| {
            self.key_pair = KeyPairInfo::builder().key_name(key_name.clone()).build();
            e.add_message(format!("Couldn't create key {key_name}"))
        })?;

        let path = self.key_file_dir.join(format!("{key_name}.pem"));

        // Save the key_pair information immediately, so it can get cleaned up if write_secure fails.
        self.key_file_path = Some(path.clone());
        self.key_pair = key_pair.clone();

        util.write_secure(&key_name, &path, material)?;

        Ok(key_pair)
    }

    TRY.
        oo_result = lo_ec2->createkeypair( iv_keyname = iv_key_name ).                            " oo_result is returned for testing purposes. "
        MESSAGE 'Amazon EC2 key pair created.' TYPE 'I'.
      CATCH /aws1/cx_rt_service_generic INTO DATA(lo_exception).
        DATA(lv_error) = |"{ lo_exception->av_err_code }" - { lo_exception->av_err_msg }|.
        MESSAGE lv_error TYPE 'E'.
    ENDTRY.