Environment agnostic applications with Spring

Slides from Szczecin Java User Group meetup that took place on the 17th of December 2014.

Story about building multienvironment applications, starting from Maven profiles, through simple property placeholder based solutions, Spring @Profiles and in the end Spring @Conditionals and Spring Boot

Transcript

1. Environment
   agnostic applications
   with Spring
   Maciej Walkowiak
   !
   

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2. " " "
   DEV TEST PROD
   How to write application for multiple
   different environments?
   

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3. Maven profiles
   Approach #1:
   

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4. Maven profiles
   mvn package -P prod
   

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5. Maven profiles
   # #
   MySQL Oracle
   

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6. Maven profiles
   # #
   MySQL Oracle
   

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7. Maven profiles
   mvn package -P prod,oracle
   # #
   MySQL Oracle
   

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8. Maven profiles
   $
   new feature!
   with two variants
   

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9. Maven profiles
   $
   new feature!
   with two variants
   

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10. Maven profiles
    $
    new feature!
    with two variants
    

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11. Maven profiles
    mvn package -P prod,oracle,feature-impl1
    $
    new feature!
    with two variants
    

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12. Maven profiles
    mvn package -P prod,oracle,feature-impl1,
    jboss,sec,s3,dk,wtf
    %
    

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13. Maven profiles
    mvn package -P prod,oracle,feature-impl1,
    jboss,sec,s3,dk,wtf
    %
    … and we’re still building one single artifact
    

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14. Configure in runtime
    Approach #2:
    

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15. • Tell application how to behave when you run it, not
    when you build it.
    • No environment specific configuration in build time.

    Build as simple as:
    Configure in runtime
    mvn package
    

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16. • Each environment has it’s own properties file on
    classpath

    

    • Picked from environmental variable
    Simple solutions often
    work
    location="classpath:application-${env}.properties"/>
    -Denv=dev
    

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17. • Since Spring 3.1 (December 2011)
    • Profiles tag group of beans into sets

    

    

    

    • There can be multiple profiles enabled at once
    • Activated by environmental variable
    Spring @Profiles
    -Dspring.profiles.active=dev
    & & &
    “dev” “test” “prod”
    

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18. Spring @Profiles
    

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19. Spring @Profiles
    

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20. Spring @Profiles
    %
    

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21. Spring @Profiles
    -Dspring.profiles.active=prod,oracle,feature-
    impl1,sec,s3,dk,wtf
    %
    

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22. Spring @Profiles
    -Dspring.profiles.active=prod,oracle,feature-
    impl1,sec,s3,dk,wtf
    %
    … too many profiles can hurt
    

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23. Spring 4 @Conditionals
    • Conditionally creates bean
    • @ConditionalOnExpression!
    • @ConditionalOnProperty!
    • @ConditionalOnClass!
    • @ConditionalOnWebApplication!
    • …!
    • “@YourCustomConditional”!
    • @Profile is just a @Conditional specialisation
    Spring Boot
    

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24. Spring 4 @Conditionals
    # one of: filesystem,s3,mongo

    storage=filesystem
    

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25. Spring 4 @Conditionals
    # one of: filesystem,s3,mongo

    storage=filesystem
    @ConditionalOnProperty(name = "storage", havingValue = "s3")

    class S3StorageService implements StorageService {

    }

    

    @ConditionalOnProperty(name = "storage", havingValue = "mongo")

    class MongoStorageService implements StorageService {

    }

    

    @ConditionalOnProperty(name = "storage", havingValue = "filesystem",
    matchIfMissing = true)

    class FileSystemStorageService implements StorageService {

    }
    

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26. Spring Boot
    • Automatically picks up right
    application-${profile}.properties !
    • YAML format support
    • Properties loading hierarchy
    Spring Boot
    

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27. Demo
    Spring Boot
    @Value
    @PropertySource
    @Configuration
    Properties
    Logback
    

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28. Build once run everywhere
    

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29. • make build process as simple as possible
    • externalize application configuration
    • externalize logging configuration
    • provide defaults!
    • use Spring Boot
    Build once run everywhere
    

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30. Q & A
    

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31. Thank you!
    ' maciejwalkowiak.pl
    (@maciejwalkowiak
    

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