The Twelve-Factor App for Node.js Developers

Transcript

1. The Twelve-Factor App
   for Node.js Developers
   by Nikita Galkin
   Feb 27, 2019
   

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2. 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
   2
   

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3. Takeaway Driven Development
   3
   TAKEAWAY
   ADOPT
   TDD
   SHARE
   

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4. 12factor.net
   

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5. What is Quality?
   5
   Motivation
   ▰ Reduce the onboarding
   time
   ▰ A common language with
   DevOps Engineers
   ▰ Scale/Cloud/Production/etc
   -ready
   

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6. What is Quality?
   6
   Talk Structure
   ▰ Factor
   ▰ RTFM
   ▰ how to implement using
   Node.js
   ▰ exclusion cases or hacks
   

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7. 7
   I. Codebase
   

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8. What is Quality?
   8
   One codebase tracked in
   revision control, many
   deploys
   ▰ App vs Distributed System
   ▰ Code sharing by
   dependency manager.
   

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9. What is Quality?
   9
   How to match codebase and
   application at env?
   ▰ semver
   ▰ version in package.json
   ▰ git tag
   ▰ git describe --tag
   Example 2.2.0-44-g9f84663
   

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10. What is Quality?
    10
    I. Codebase
    ▰ BE & FE aka Full-stack repo
    ▰ App & lambda from one src
    ▰ Monorepo
    

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11. 11
    II. Dependencies
    

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12. What is Quality?
    12
    Explicitly declare and
    isolate dependencies
    ▰ declaration VS isolation
    ▰ never relies on implicit
    existence
    ▰ system tool can be a
    dependency
    

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13. What is Quality?
    13
    Package.json
    ▰ avoid npm install -g ...
    ▰ package-lock.json should published in git
    ▰ node & npm versions fixed at Tech Stack
    or you will have package-lock diff war
    ▰ post-install script is a good place for hacking
    node_modules
    

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14. 14
    Scoped packages
    

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15. What is Quality?
    15
    Shared code
    ▰ 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
    

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16. What is Quality?
    16
    

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17. What is Quality?
    17
    node_modules hacks
    ▰ Embedded or lambda: webpack
    ▰ Docker
    ▻ npm install --production
    ▻ npm prune --production
    ▻ node-prune
    ▻ docker in docker
    

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18. FROM node:10.15-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 yarn.lock $APP_WORKDIR
    WORKDIR $APP_WORKDIR
    RUN yarn install
    COPY . $APP_WORKDIR
    RUN yarn build
    RUN rm -rf tsconfig.json src
    RUN apk del build-deps
    RUN yarn install --production
    RUN yarn cache clean
    EXPOSE 3000
    CMD ["node", "dist/index.js"]
    

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19. 19
    III. Config
    

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20. What is Quality?
    20
    Store config in the
    environment
    ▰ Config is not part of the
    artifact
    ▰ could be made open source
    at any moment, without
    compromising any
    credentials.
    

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21. What is Quality?
    21
    .env
    ▰ Use .env file for local development
    ▰ Use .env.example file for description
    ▰ Use environment variables for any other
    environment
    ▰ Don’t use default config values in your code
    ▰ Break your start process if any value missed
    

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22. # .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
    

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23. 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;
    

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24. What is Quality?
    24
    Dima: process.env knows
    every env var. This is
    risky!
    Nikita: Then your project
    uses only 11 factors.
    

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25. 25
    IV. Backing
    services
    

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26. What is Quality?
    26
    Treat backing services as
    attached resources
    ▰ local and third party parity
    ▰ Attach URL or other
    locator/credentials stored
    in the config
    

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27. What is Quality?
    27
    Nice to have
    ▰ Tech stack for project
    or Readme.md with strict versions
    ▰ For local development
    docker-compose file
    or minikube config file
    

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28. 28
    V. Build, release,
    run
    

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29. What is Quality?
    29
    Strictly separate build and
    run stages
    ▰ Artifact
    ▰ Build
    ▰ Release
    ▰ Run time
    ▰ Dry run
    

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30. What is Quality?
    30
    Node.js artifact
    ▰ N/A
    ▰ Docker
    ▰ Lambda zip
    ▰ Application Zip
    ▻ Big size
    ▻ node-gyp compiled code can be broken on
    another computer
    

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31. 31
    VI. Processes
    (stateless)
    

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32. What is Quality?
    32
    Execute the app as one or
    more stateless processes
    ▰ stateless
    ▰ share-nothing
    ▰ state stored at
    backing-service
    

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33. Awesome Pair!
    Docker and Node.js
    has a common thing
    – single process
    

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34. 34
    6 Done, 6 Left
    Let’s move faster
    

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35. 35
    VII. Port binding
    Export services via port
    binding
    

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36. What is Quality?
    36
    ▰ Don’t hardcode port at the code,
    use env vars
    ▰ Bootstrap should fail,
    if the port is not available
    ▰ Dockerfile EXPOSE
    

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37. 37
    VIII. Concurrency
    Параллелизм
    

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38. What is Quality?
    38
    Scale out via the process
    model
    ▰ Unix
    ▰ process
    ▰ should never daemonize
    ▰ Use process manager like
    systemd
    

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39. 39
    IX. Disposability
    Maximize robustness with fast startup
    and graceful shutdown
    

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40. 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);
    

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41. 41
    X. Dev/prod parity
    Keep development, staging, and
    production as similar as possible
    

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42. What is Quality?
    42
    ▰ Same backing services
    ▰ Same lib versions
    ▰ Same bla-bla for
    Reproducibility
    

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43. 43
    XI. Logs
    Treat logs as event streams
    

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44. What is Quality?
    44
    ▰ 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
    ▰ bunyan has this format from the box
    ▰ for local development
    npm start | bunyan -o short
    

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45. stdout stderr
    

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46. 46
    XII. Admin
    processes
    Run admin/management tasks as
    one-off processes
    

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47. What is Quality?
    47
    ▰ Node.js has REPL
    ▰ Check node_modules/.bin
    every script starts with
    #!/usr/bin/env node
    ▰ Write your own script or reuse packages
    ▰ Use npx, for example
    npx https://gist.github.com/galkin/9b54683ec251d77b26fa4c7feec46df2
    

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48. 12factor.net
    

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49. 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
    

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