Work Journal - RACV 2020 - 2021

I was contracting to RACV Home Emergency as a senior full-stack engineer for about a year.

Nontechnical

• Finally I met an awesome tech lead - Asheesh Karwal, who:
  • has no big ego, does not try to be the loudest or smartest voice in the room
  • thinks through tasks beforehand, assesses technical solutions and challenges
  • kicks off tasks with individual engineers, hashes out ideas and concerns
  • writes code review comments with respect, usually proposes alternative code snippet
  • is willing to work on the not so glorious tech debts in the background
  • walks through his code changes with fellow engineers

Technical

• Technical decisions that caused high codebase maintenance overhead and steep learning curve for newcomers:

  • Dependency Injection in Javascript codebase, without a typing system
  • Hand-crafted GraphQL resolvers, without a convenient framework

• How to write a comprehensive system architecture design document

• Infra / DevOps

  • Epsagon - backend monitoring
  • Sentry - frontend bug tracking ⭐️
  • OpsGenie
  • AWS RDS Aurora Serverless
  • use AWS SSO to grant CLI access ⭐️
    • serverless.com framework doesn't support AWS SSO CLI2 well
  • AWS RDS DB tunnel with a bastion instance ⭐️

• Node.js backend

  • use AWS SSM and Secrets Manager for deployment configuration and env vars ⭐️
  • modularise and isolate data model CRUD operation around the domain
  • npm ci

    Copycopy code to clipboard
    1# yarn equivalent
    2yarn install --frozen-lockfile

  • eslint-no-return-await
  • sanitize-html ⭐️
  • lodash.template - lightweight than handlebars ⭐️
  • http://npm.broofa.com/ - see npm dependencies graph
  • optional chaining - available in node.js
  • umzug - framework-agnostic SQL-like DB migration tool for Node ⭐️
  • use key-value pairs to replace large switch-case-return ⭐️
  • knex.js - lightweight than TypeORM, suitable for Lambda function

• SQL

  Copycopy code to clipboard
  1INSERT IGNORE INTO ...
  2
  3INSERT INTO ... ON DUPLICATE KEY
  4
  5START TRANSACTIONS ... COMMIT
  6
  7DELETE/UPDATE ... WHERE ... LIMIT 1 ⭐️

• React/React Native frontend

  • double escaping issue
  • react-hook-form ⭐️
  • testing-library - UI unit test, kinda verbose
  • debug in Chrome Dev Tools
  • use context to implement periodic time-based refresh ⭐️

  Copycopy code to clipboard
  1const TimeContext = createContext({
  2    now: new Date(),
  3    updateTimeContext: () => {},
  4});
  5
  6const TimeProvider = ({ children }) => {
  7    const FORTY_SECONDS = 40000;
  8    const [now, setNow] = useState(new Date());
  9
  10    const updateTimeContext = () => setNow(new Date());
  11    useInterval(updateTimeContext, FORTY_SECONDS);
  12
  13    return (
  14        <TimeContext.Provider value={{ now, updateTimeContext }}>
  15            {children}
  16        </TimeContext.Provider>
  17    );
  18};
  19
  20export default TimeProvider;
  21export { TimeContext };

• GraphQL

  • apollo-boost vs apollo-client
  • use type condition ⭐️
  • union ⭐️
  • interface and implement
  • Solving N+1 problem with data loader ⭐️

• serverless

  • Authenticate API Gateway with Cognito User Pool, using Amplify libs on frontend
  • serverless-jetpack - speed up serverless framework deployment
  • fine-tune deployment package, example:

  Copycopy code to clipboard
  1package:
  2  exclude:
  3    - '*'
  4    - '*/**'
  5    - '!node_modules/**'
  6  include:
  7    - package.json
  8    - 'src/**'
  9    - '!src/**/__tests__'
  10    - '!src/**/__mocks__'

  • locally invoke Lambda function to perform tasks like RDS migrations, ad-hoc data reporting ⭐️
  • npm chrome-aws-lambda - so we could render React component as PDF ⭐️