Twelve-Factor app with Docker

Transcript

1. Twelve-Factor app with Docker
   Posobota 107.
   @ujovlado
   

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2. whoami
   Developer at Keboola
   interested in infrastructure/devops and UI/UX
   building data platform Keboola Connection
   writing about it at 500.keboola.com
   Occasional speaker, geek and blogger
   twitter.com/ujovlado
   medium.com/@ujovlado
   ujovlado.dev
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3. What is Twelve-Factor app?
   https://12factor.net
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4. I. Codebase
   One codebase tracked in revision control, many deploys
   II. Dependencies
   Explicitly declare and isolate dependencies
   III. Config
   Store config in the environment
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5. IV. Backing services
   Treat backing services as attached resources
   V. Build, release, run
   Strictly separate build and run stages
   VI. Processes
   Execute the app as one or more stateless processes
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6. VII. Port binding
   Export services via port binding
   VIII. Concurrency
   Scale out via the process model
   IX. Disposability
   Maximize robustness with fast startup and graceful shutdown
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7. X. Dev/prod parity
   Keep development, staging, and production as similar as
   possible
   XI. Logs
   Treat logs as event streams
   XII. Admin processes
   Run admin/management tasks as one-off processes
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8. Twelve-Factor app with Docker
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9. I. Codebase, II. Dependencies
   Doesn't matter if you have Docker or not
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10. III. Config
    Environment variables passed to container
    Typical example: APPLICATION_ENV=dev/prod
    Then decide if debug mode, extended logging is turned
    off/on or if there will be more verbose output
    You can use configuration file and pass it to app at "startup"
    phase
    File downloaded from some storage (e.g. AWS S3)
    Use "credentials storage" and create file manually
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11. IV. Backing services
    Everything outside of an app is a resource for you
    Container has to be ready to use different "provider" in seconds
    Typical examples:
    Local MySQL in other container vs. RDS
    SMTP configuration
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12. V. Build, release, run
    Copy whole code to image, install dependencies
    Push image to image repository
    Run container (optionally override ENTRYPOINT and CMD)
    There are no symlinks, when you need to deploy new version you
    start container with different image
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13. VI. Processes
    You should never run more services in one container
    If there are more processes, these processes should be child
    processes of main service (e.g. Apache)
    Workers has typically one process
    If main process (PID: 1) ends, container should end too
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14. VII. Port binding
    Your service should be a "black box" exposing only a port (and
    load balancer will forward traffic to this port)
    Very easy with Docker
    FROM php:7.3-apache
    Image with PHP and Apache which already exposing
    port 80
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15. VIII. Concurrency
    If processes are stateless there should'n be problem with
    concurrency
    You just start more containers
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16. IX. Disposability
    Docker image is pulled before first deploy, start will be fast
    More important is SIGTERM handling
    Example: Worker is processing messages from queue and
    after SIGTERM signal it will stop requesting more, process
    last message and end with 0 code
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17. X. Dev/prod parity
    Local build of image and code mounted as volume
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18. XI. Logs
    App should not care how its logs will be processed
    Log everything to stdout
    Other service will process your logs
    Other container with mounted Docker socket sending logs
    to other service
    Orchestration service will send logs to other service
    Syslog is overhead
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19. XII. Admin processes
    Same as other services, container ends after processing
    Example: DB migrations, Garbage Collection
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20. Questions?
    

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