12FactorAppInJava

12FactorAppInJava

I. Codebase
One codebase tracked in revision control, many deploys

1.Use VCS( Git, Mercurial, or Subversion. )
2.1 app 1 code repository
3.1 app 1 or many deploy(production , testing , develop1 , develop2 ...)
4.deploy can be different version , but from same code repo.

II. Dependencies
Explicitly declare and isolate dependencies

1. use maven,ivy or gradle to manage dependencies.
2. use sonar nexus will be plus


III. Config
Store config in the environment

1. less CONFIG IN AP Server setting
2. use properties
3. config store
    1. Resource handles to the database, Memcached, and other backing services
    2. Credentials to external services such as Amazon S3 or Twitter
    3. Per-deploy values such as the canonical hostname for the deploy
4. -> Config varies substantially ACROSS deploys, code does not.
5. “config” does not include internal application config
    1. Spring java config(@Configuration,application-context.xml)
6. Database can like ruby config/database.yml(http://stackoverflow.com/questions/5872264/correct-mysql-configuration-for-ruby-on-rails-database-yml-file)
7. STORE config file path in environment variables.
8. discuess
   1. (http://redd.it/2n122s , http://redd.it/2r38xr)
   2. http://movingfast.io/articles/environment-variables-considered-harmful/
   3. https://gist.github.com/telent/9742059
   4. https://spring.io/blog/2015/01/13/configuring-it-all-out-or-12-factor-app-style-configuration-with-spring
8. example
   1. http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/create_deploy_Java.managing.html#create_deploy_Java.managing.accessing
   2. http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/customize-containers-ec2.html#customize-containers-format-options
   3. http://blog.doismellburning.co.uk/2014/10/06/twelve-factor-config-misunderstandings-and-advice/

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

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

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