API Lambda Example

This project contains a simple API for practice purpose and maybe for new learners like me who explores the aws serverless world.

A user can have N of posts and has a daily limit of posts that we can attach.

Techs Used

• Node js / Typescript
• AWS (Lambda, API Gateway, Route 53, CodeArtifact)
• Serverless Framework

Main library used in Node js

• Joi used for API validation
• Typegoose used to define Mongoose models using TypeScript classes
• Mongoose to interact with database
• Inversify an IoC container uses a class constructor to identify and inject its dependencies.

Architecture

I used the single purpose function in lambda trilogy. Functions are grouped into module and each module are attached to an API gateway and glued together using custom domain.

I used AWS CodeArtifact to make a private repository called ksr/shared where all common codes reside, we can used it in each module to avoid repetition of codes and also this is where all the queries abstracted using repository pattern belonged.

• One question that comes into my mind when making this is what if I needed the createPost method in the createUser method, well I just make a service in each module and just import it if needed in the future. By doing this I can avoid using the lambda invoke (aws-sdk) which will make the request more slower because it will initiate a new connection on the database.

Folder structure

Top folder is represented by module name (except for repositories), each files under src are lambda functions.

└── posts/
    ├── src/
    │   ├── createPost.ts
    │   └── getAllPosts.ts
    └── tests/
        └── ...
└── repositories/
    ├── di
    ├── modules
    ├── shared
    └── tests

repositories folder

repositories / @ksr/shared folder or the private repository that represents the common codes used by each modules (users, posts, users posts)

• di has files that are needed for dependency injection e.g. container.ts
• modules has files that represent each module (I used repository pattern)
• shared has files that are common and might be used in each lambda fns.

Notes: if we build or test the project there's additional folder included like coverage and dist

API reference

Get all users

• <API_GATEWAY_URL>/user-management/users (GET)

Create User

• <API_GATEWAY_URL>/user-management/user (POST)

  {
    "name": "test",
    "dailyLimit": 2
  }
  

Get all posts

• <API_GATEWAY_URL>/post-management/posts (GET)

Create post

• <API_GATEWAY_URL>/post-management/post (POST)

  {
    "title": "test6",
    "description": "desc6"
  }
  

Get all users posts

• <API_GATEWAY_URL>/user-post-management/users-posts (GET)

Attach posts to user

• <API_GATEWAY_URL>/user-post-management/user-post (POST)

  {
    posts: ["62aace7f0406a73d0c3742ec", "62aad0631e145e6b829d2625"],
    userId: "62aae23a7e64ab93f1b6eedc"
  }
  

Todos maybe

• CI/CD for each module and if we commit our code only the changed files under a specific module should be deployed (monorepo), I'm still exploring this and still not sure how to implement it lol.
• AWS cognito for auth purpose and to protect the API's
• multi environment setup