Stack Name - AWS Lambda

Synopsis

The is the base reusable implementation for AWS Lambda type tech stacks while indirectly using Hibernate for relation database integration The stack includes:

• Spark Micro Framework:
  • A lightweight alternative to heavier Java frameworks like Spring or Strut2, and is great for microservices implementations
  • Provide a remote replica Restful API with constant relational database connection to ensure fast execution time with minimal latency for Lambda functions executing in scenarios where the data must be stored in a relational database
  • Hibernate:
    • An object–relational mapping tool for the Java programming language. It provides a framework for mapping an object-oriented domain model to a relational database

Design Consideration

Problem To date, it is frowned upon using Lambda functions in scenarios where direct connectivity to a relational database is required.  This is due to the unacceptable latency caused by making a database connection per call.  Since a server-less function is stateless by definition, a database connection cannot be cached. Also, a relational database has concurrent connection limitations. Solution Harbormaster overcomes this well known Lambda to Relational DB problem by generating a replica Restful API.  Each Lambda function delegates to an associate Restful API to perform the read/write to the database.  This design keeps in place the value of a server-less API while providing the integrity and low-latency demanded of consumers.  Importantly, other applications can take advantage of the Restful API as well.

Details

Author	dev@harbormaster.ai
Access	Public
Derived From	.java.tech.stack .lambda.tech.stack .hibernate.tech.stack
Long Name	AWS Lambda
Short Name	Lambda
Language(s)	Java 8+, NodeJS, YAML, XML, Velocity Macros
Git Url	https://github.com/Harbormaster-AI/cli/blob/main/samples/yamls/project.as.code/aws-lambda-rdbms-project-as-code.yml
Example Project YAML	https://github.com/Harbormaster-AI/cli/blob/main/samples/yamls/project.as.code/aws-lambda-rdbms-project-as-code.yml

Contents

Along with what is supported by the parent tech stacks the following are overridden and additional capabilities:

• Build:
  • Overloaded CI vendor specific macros to apply specifics for this tech stack, such as AWS and Hibernate settings, etc..
• Spark Micro Web Framework:
  • All templates and Velocity macros used to create a complete Restful API for all CRUD capabilities along with persistence via Hibernate

Important AWS Considerations

Using Terraform

If Harbormaster is enabled to generate Terraform file(s) for AWS, it will create a secure EC2 instance with a running MongoDB database instance.  Each lambda function will have an environment variable assigned called mongoDbServerAddresses.  Its value is the URL(s) to the MongoDB instance(s) to be used by each lambda function for reading and writing.

Authentication

For any CI platform, be sure to assign environment variables USERAWSACCESSKEY and USERAWSSECRETKEY to their respective values as assigned by AWS.  Refer to the CI platform on how to assign environment variables.

Options

See .lambda.tech.stack options and .hibernate.tech.stack.options

Options

Option Name	description	Type	values
apollo
service		input
buildAndCopyResultLayer	build and push DAO layer as an executable jar file	boolean	default: true
securityRemoteUrl	security account with URL to copy DAO Restful API to	input
fileLocation	file location on remote service to copy DAO restful API	select	react angular
privateKeyFileLocation	private SSH key file location
passphrase	passphrase for key file, leave empty if none	input

Usage

See .lambda.tech.stack usage

Deploy the Generated Restful API Layer

In the root directory of the generated project is a generated Maven pom-restful-api.xml file that contains the declarations and dependencies to run the Restful API Layer within the Spark container.

mvn clean install -f pom-restful-api.xml

By default, Spark listens on port 4567, accessible through the browser via:

http://your_host_name_or_ip_address:4567