Elastic Beanstalk examples using SDK for Ruby

# Class to manage Elastic Beanstalk applications
class ElasticBeanstalkManager
  def initialize(eb_client, logger: Logger.new($stdout))
    @eb_client = eb_client
    @logger = logger
  end

  # Lists applications and their environments
  def list_applications
    @eb_client.describe_applications.applications.each do |application|
      log_application_details(application)
      list_environments(application.application_name)
    end
  rescue Aws::ElasticBeanstalk::Errors::ServiceError => e
    @logger.error("Elastic Beanstalk Service Error: #{e.message}")
  end

  private

  # Logs application details
  def log_application_details(application)
    @logger.info("Name:        #{application.application_name}")
    @logger.info("Description: #{application.description}")
  end

  # Lists and logs details of environments for a given application
  def list_environments(application_name)
    @eb_client.describe_environments(application_name: application_name).environments.each do |env|
      @logger.info("  Environment:  #{env.environment_name}")
      @logger.info("    URL:        #{env.cname}")
      @logger.info("    Health:     #{env.health}")
    end
  rescue Aws::ElasticBeanstalk::Errors::ServiceError => e
    @logger.error("Error listing environments for application #{application_name}: #{e.message}")
  end
end

# Manages listing of AWS Elastic Beanstalk solution stacks
# @param [Aws::ElasticBeanstalk::Client] eb_client
# @param [String] filter - Returns subset of results based on match
# @param [Logger] logger
class StackLister
  # Initialize with AWS Elastic Beanstalk client
  def initialize(eb_client, filter, logger: Logger.new($stdout))
    @eb_client = eb_client
    @filter = filter.downcase
    @logger = logger
  end

  # Lists and logs Elastic Beanstalk solution stacks
  def list_stacks
    stacks = @eb_client.list_available_solution_stacks.solution_stacks
    orig_length = stacks.length
    filtered_length = 0

    stacks.each do |stack|
      if @filter.empty? || stack.downcase.include?(@filter)
        @logger.info(stack)
        filtered_length += 1
      end
    end

    log_summary(filtered_length, orig_length)
  rescue Aws::Errors::ServiceError => e
    @logger.error("Error listing solution stacks: #{e.message}")
  end

  private

  # Logs summary of listed stacks
  def log_summary(filtered_length, orig_length)
    if @filter.empty?
      @logger.info("Showed #{orig_length} stack(s)")
    else
      @logger.info("Showed #{filtered_length} stack(s) of #{orig_length}")
    end
  end
end

# Manages deployment of Rails applications to AWS Elastic Beanstalk
class RailsAppDeployer
  def initialize(eb_client, s3_client, app_name, logger: Logger.new($stdout))
    @eb_client = eb_client
    @s3_client = s3_client
    @app_name = app_name
    @logger = logger
  end

  # Deploys the latest application version to Elastic Beanstalk
  def deploy
    create_storage_location
    zip_file_name = create_zip_file
    upload_zip_to_s3(zip_file_name)
    create_and_deploy_new_application_version(zip_file_name)
  end

  private

  # Creates a new S3 storage location for the application
  def create_storage_location
    resp = @eb_client.create_storage_location
    @logger.info("Created storage location in bucket #{resp.s3_bucket}")
  rescue Aws::Errors::ServiceError => e
    @logger.error("Failed to create storage location: #{e.message}")
  end

  # Creates a ZIP file of the application using git
  def create_zip_file
    zip_file_basename = SecureRandom.urlsafe_base64
    zip_file_name = "#{zip_file_basename}.zip"
    `git archive --format=zip -o #{zip_file_name} HEAD`
    zip_file_name
  end

  # Uploads the ZIP file to the S3 bucket
  def upload_zip_to_s3(zip_file_name)
    zip_contents = File.read(zip_file_name)
    key = "#{@app_name}/#{zip_file_name}"
    @s3_client.put_object(body: zip_contents, bucket: fetch_bucket_name, key: key)
  rescue Aws::Errors::ServiceError => e
    @logger.error("Failed to upload ZIP file to S3: #{e.message}")
  end

  # Fetches the S3 bucket name from Elastic Beanstalk application versions
  def fetch_bucket_name
    app_versions = @eb_client.describe_application_versions(application_name: @app_name)
    av = app_versions.application_versions.first
    av.source_bundle.s3_bucket
  rescue Aws::Errors::ServiceError => e
    @logger.error("Failed to fetch bucket name: #{e.message}")
    raise
  end

  # Creates a new application version and deploys it
  def create_and_deploy_new_application_version(zip_file_name)
    version_label = File.basename(zip_file_name, ".zip")
    @eb_client.create_application_version(
      process: false,
      application_name: @app_name,
      version_label: version_label,
      source_bundle: {
        s3_bucket: fetch_bucket_name,
        s3_key: "#{@app_name}/#{zip_file_name}"
      },
      description: "Updated #{Time.now.strftime('%d/%m/%Y')}"
    )
    update_environment(version_label)
  rescue Aws::Errors::ServiceError => e
    @logger.error("Failed to create or deploy application version: #{e.message}")
  end

  # Updates the environment to the new application version
  def update_environment(version_label)
    env_name = fetch_environment_name
    @eb_client.update_environment(
      environment_name: env_name,
      version_label: version_label
    )
  rescue Aws::Errors::ServiceError => e
    @logger.error("Failed to update environment: #{e.message}")
  end

  # Fetches the environment name of the application
  def fetch_environment_name
    envs = @eb_client.describe_environments(application_name: @app_name)
    envs.environments.first.environment_name
  rescue Aws::Errors::ServiceError => e
    @logger.error("Failed to fetch environment name: #{e.message}")
    raise
  end
end