The Twelve-Factor App for Node.js Developers at KharkivJS

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1. The Twelve-Factor App for Node.js Developers by Nikita Galkin Oct 5, 2019
2. What is Quality? 2 Motivation Reduce onboarding time A common language with DevOps Engineers Scale-ready app Cloud-ready app Production-ready app Etc-ready app
4. Nikita Galkin Love and Know: ▰ How to make developers and business happy ▰ Technical and process debt elimination Believe that: ▰ Any problem must be solved at the right level ▰ Software is easy. People Are Complicated ▰ A problem should be highlighted, an idea should be "sold", a solution should be demonstrated Links: Site GitHub Twitter Facebook
5. 12factor.net
6. I. Codebase One codebase tracked in revision control, many deploys
7. What is Quality? 9
9. 11 Scoped packages
10. What is Quality? 12 Shared code: ▰ Don’t use gitsubmodules, use scoped packages ▰ @project/code-style is good first chose Check Code Style and Violence by Anton Nemtsev ▰ On self-hosted repo npm config set @myco:registry http://reg.example.com ▰ With a self-hosted repo, use add .npmrc to git
11. II. Dependencies Explicitly declare and isolate dependencies
13. What is Quality? 15 Package.json ▰ avoid npm install -g ... ▰ package-lock.json should published in git ▰ node & npm versions fixed ▰ post-install script is a good place for hacking node_modules
14. What is Quality? 16
15. FROM node:10.16.3-alpine ENV APP_WORKDIR=/usr/src/app RUN apk update && apk upgrade && \ apk add --virtual build-deps git openssh-client py-pip make COPY package.json package-lock.json $APP_WORKDIR WORKDIR $APP_WORKDIR RUN npm install COPY . $APP_WORKDIR RUN npm run build RUN rm -rf tsconfig.json src RUN apk del build-deps RUN npm prune --production CMD ["node", "dist/index.js"]
16. III. Config Store config in the environment
17. What is Quality? 19 ▰ Config is not part of the artifact ▰ App could be made open source at any moment, without compromising any credentials.
18. What is Quality? 20 .env ▰ Use .env.example file for description ▰ Use .env file for local development ▰ Use environment variables for any other environment ▰ Don’t use default config values in your code ▰ Break your start process if any value missed
19. # .env.example # Default log level LOG_LEVEL=info # Graceful shutdown timeout in milliseconds SHUTDOWN_TIMEOUT=1000 # HTTP Boundary port HTTP_PORT=8000 # Redis connection string REDIS_URI=redis://127.0.0.1:6379
20. require('dotenv-safe').load({ allowEmptyValues: true, path: join(__dirname, '..', '.env'), sample: join(__dirname, '..', '.env.example') }); const logger = require('./logger'); logger.levels('stdout', process.env.LOG_LEVEL); const settings = { shutdownTimeout: process.env.SHUTDOWN_TIMEOUT, http: { port: process.env.HTTP_PORT, }, redis: { uri: process.env.REDIS_URI, }, }; module.exports = settings;
21. What is Quality? 23 Dima: process.env knows every env var. This is risky! Nikita: Then your project uses only 11 factors.
22. IV. Backing services Treat backing services as attached resources
23. What is Quality? 25 ▰ local and third party parity ▰ Use connection string is URL and can be used as locator/credentials ▰ Native Node.js module url has parse method ▰ Repeat III. Config one more time
24. What is Quality? 26 Nice to have ▰ Tech stack for project or Readme.md with strict versions ▰ For local development docker-compose file or minikube config file
25. V. Build, release, run Strictly separate build and run stages
26. What is Quality? 28 ▰ Artifact ▰ Build ▰ Release ▰ Run time ▰ Dry run
27. What is Quality? 29 Node.js artifact ▰ N/A ▰ Docker ▰ Lambda zip ▰ Application Zip ▻ Big size ▻ node-gyp compiled code can be broken on another computer
28. VI. Processes Execute the app as one or more stateless processes
29. What is Quality? 31
30. Awesome Pair! Docker and Node.js has a common thing – single process
32. VII. Port binding Export services via port binding
33. What is Quality? 35 ▰ Don’t hardcode port at the code, use env vars ▰ Bootstrap should fail, if the port is not available ▰ Dockerfile EXPOSE directive depence on deploy, but 9229...
34. VIII. Concurrency Scale out via the process model
35. What is Quality? 37 ▰ Unix process model ▰ should never daemonize ▰ Use process manager like systemd/pm2/etc ▰ process and cluster are first class citizen
36. IX. Disposability Maximize robustness with fast startup and graceful shutdown
37. const server = app.listen(settings.port, () => { logger.info(`Server started on port ${settings.port}`); }); function stopHandler(){ logger.info(`Stopping server on port ${settings.port}`); const timeout = setTimeout(() => { logger.info(`Server on port ${settings.port} stop forcefully`); process.exit(1); }, settings.stopTimeout); server.close(() => { logger.info(`Server on port ${settings.port} stopped`); clearTimeout(timeout); }); }; process.on('exit', (code) => logger.info(`Exit with code: ${code}`)); ['SIGTERM','SIGINT','SIGHUP'] .forEach(signal => process.on(signal, stopHandler);
38. X. Dev/prod parity Keep development, staging, and production as similar as possible
39. What is Quality? 41 ▰ Same backing services ▰ Same lib versions ▰ Same bla-bla for Reproducibility
40. XI. Logs Treat logs as event streams
41. What is Quality? 43 ▰ A twelve-factor app never concerns itself with routing or storage of its output stream ▰ Writes event stream, unbuffered, to stdout/stderr ▰ JSON format for simplification log parsing ▰ pino has this format from the box ▰ for local development use pino pretty
42. stdout stderr
43. XII. Admin processes Run admin/management tasks as one-off processes
44. What is Quality? 46 ▰ Node.js has REPL, so be DevOps Engineer ▰ Check node_modules/.bin every script starts with #!/usr/bin/env node ▰ Write your own script or reuse packages ▰ Database migrations ▰ Your own CLI with typescript decorators with clime package
45. 12factor.net
46. 49 THANKS! Happy coding with 12 factors! You can find me on Twitter as @galk_in Slides are available at speakerdeck.com/galkin or at my site galk.in