12 Factor App. Best Practices for Scala Deployment

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12

Factor App

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2005

2015

WAR files

JAR files

App Servers

Microservices

Java

Scala

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Joe Kutner

@codefinger

JVM Platform Owner @Heroku

(4)

12

Factor App

a methodology

Scalability

Maintainability

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•

Immutable

•

Ephemeral

•

Declarative

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addSbtPlugin(

"com.typesafe.sbt" % "sbt-native-packager" % "0.7.6"

)

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The

12

Factors

• Codebase

• Dependencies • Config

• Backing services • Build, release, run • Processes • Port binding • Concurrency • Disposability • Dev/prod parity • Logs • Admin processes

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Thank You! Goodbye! (just kidding)

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The

12

Factors

• Codebase

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The

12

Factors

• Codebase

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BAD

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my-project ! build.sbt ! app ! conf ! public ! my-library ! build.sbt ! src ! main ! scala

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my-project ! build.sbt ! app ! conf ! public ! my-library ! my-sub-project ! build.sbt ! src ! main ! scala BAD

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The

12

Factors

• Codebase

• Dependencies

• Config

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Never rely on implicit existence of system-wide

packages Explicitly declare

and isolate dependencies

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global local BAD GOOD

Dependencies

~/.m2 ~/.ivy2 (ok in dev) target/

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Vendoring

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$ sbt stage ... $ tree target/universal/stage/lib/ target/universal/stage/lib/ "## ch.qos.logback.logback-classic-1.1.1.jar "## ch.qos.logback.logback-core-1.1.1.jar "## com.fasterxml.jackson.core.jackson-annotations-2.3... "## com.fasterxml.jackson.core.jackson-core-2.3.2.jar "## com.fasterxml.jackson.core.jackson-databind-2.3.2.jar "## com.google.guava.guava-16.0.1.jar ...

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The

12

Factors

• Codebase

• Dependencies

• Config

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Or was it “DUH”?

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Can you make your app open source

at any moment, without compromising any credentials?

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• Resource handles to the database,

Memcached, and other backing services • Credentials to external services such as

Amazon S3 or Twitter

• Per-deploy values such as the canonical hostname for the deploy

Anything that changes between deployment environments:

(does not include things like conf/routes)

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Configuration belongs in the environment,

not in the application Configuration should

be strictly separated

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db.default.url=${DATABASE_URL}

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The

12

Factors

• Codebase

• Backing services

• Build, release, run • Processes • Port binding • Concurrency • Disposability • Dev/prod parity • Logs • Admin processes

(38)

db.default.url=${DATABASE_URL}

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The

12

Factors

• Codebase

• Build, release, run

• Processes • Port binding • Concurrency • Disposability • Dev/prod parity • Logs • Admin processes

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$ sbt stage ... $ sbt deployHeroku ... # in the cloud! $ target/universal/stage/bin/my-app build release run

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$ sbt run

BAD

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The

12

Factors

• Codebase

• Dependencies

• Config

• Build, release, run

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$ sbt stage ... $ sbt deployHeroku ... # in the cloud! $ target/universal/stage/bin/scaladays build release run

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The

12

Factors

• Codebase

• Backing services • Build, release, run

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sticky sessions 😞

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The

12

Factors

• Codebase

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The twelve-factor app

is completely self-contained

The web app exports HTTP as a service by binding to a port

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.war

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.jar

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The

12

Factors

• Codebase

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Actors

Futures

Agents

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Scale Up

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web.1 web.2 worker.1 clock.1 Workload Diversity Number of Pr ocesses worker.2 worker.3

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The

12

Factors

• Codebase

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Graceful shutdown Quick startup

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Servers are not pets

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Application Servers are not disposable

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Microservices are disposable

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Easy to replace

Decoupled from

external infrastructure Easy to modify

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The

12

Factors

• Codebase

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dev

sqlite

postgres

stage

mysql

postgres

prod

postgres

=

≠

=

≠

=

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dev

jetty

stage

tomcat

jetty

prod

jboss

jetty

=

≠

=

≠

=

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dev

jetty

{}

stage

tomcat

{}

prod

jboss

{}

=

≠

=

≠

=

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disposable

reproducible

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The

12

Factors

• Codebase

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The

12

Factors

• Codebase

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Admin tasks should be run in isolated processes

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$ heroku run console

Running `console` attached to terminal... up, run.2581

Picked up JAVA_TOOL_OPTIONS: -Djava.rmi.server.useCode... Failed to created JLineReader: java.lang.NoClassDefFou... Falling back to SimpleReader.

Welcome to Scala version 2.11.1 (OpenJDK 64-Bit Server... Type in expressions to have them evaluated.

Type :help for more information. scala>

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web1

web2

web3

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$ heroku run sbt console

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addSbtPlugin(

"com.typesafe.sbt" % "sbt-native-packager" % "0.7.6"

)

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console: target/universal/stage/bin/my-app \ -main scala.tools.nsc.MainGenericRunner \ -usejavacp Procfile worker: target/universal/stage/bin/my-app \ -main com.example.MyWorker

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The

12

Factors

• Codebase

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http://

12

factor

.

net

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Add sbt-native-packager 1. Run `sbt stage` 2. Deploy to Heroku? 3.

Go to the sbt-native-packager talk

4.

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Joe Kutner

@codefinger

JVM Platform Owner @Heroku

http://12