This are the slides for my lightning talk at the Vienna Scala Usergroup on September 14th 2017 about running Playframework Applications inside Docker containers.

1. PLAY ON DOCKER
Daniel Pfeiffer - @pfeiffer_d_

2. IT'S EASY BECAUSE
EVERYONE DOES IT

3. CLASSIC DOCKERFILE
BUILD THE IMAGE
FROM anapsix/alpine-java:8u141b15_jdk
COPY ./target/scala-2.12/assembly.jar /app/assembly.jar
EXPOSE 9000
ENTRYPOINT ["java", "-jar", "/app/assembly.jar"]
docker build -t com.github.dpfeiffer/play-docker-showcase .

4. DOCKERFILE WITH SBT
BUILD THE IMAGE
addSbtPlugin("se.marcuslonnberg" % "sbt-docker" % "1.4.1")
dockerfile in docker := {
new Dockerfile {
from("anapsix/alpine-java:8u141b15_jdk")
copy(assembly.value, "/app/assembly.jar")
expose(9000)
entryPoint("java", "-jar", "/app/assembly.jar")
}
}
sbt docker

5. I PREFER A START SCRIPT
#!/usr/bin/env bash
exec java -jar /app/assembly.jar
dockerfile in docker := {
new Dockerfile {
from("anapsix/alpine-java:8u141b15_jdk")
copy(assembly.value, "/app/assembly.jar")
copy(file("./start.sh"), "/app/start.sh")
run("chmod", "+x", "/app/start.sh")
expose(9000)
cmd("/app/start.sh")
}
}

6. HANDS ON

7. CODE
See my Github Repository

8. RUNNING THE APPLICATION
Build the Docker image with
Run the Docker image with
sbt docker
docker run -m 128M -it --rm -p 9000:9000 -name showcase
-e PLAY_HTTP_SECRET_KEY=changed
com.github.dpfeiffer/play-docker-showcase

9. USEFUL COMMANDS
View the Docker container stats
Enter the container bash
Get a memory overview of the JVM inside the
container
docker stats showcase
docker exec -it showcase /bin/bash
jcmd 1 VM.native_memory summary

10. WITH ‐XMX YOU SET THE MAX
MEMORY...

11. FINAL THOUGHTS
existing VM flags are not enough
non-heap at least is "predictable"
"micro" services on the JVM are not that micro
use small base images to save traffic
non heap grows over time, keep some space

12. LINKS
https://github.com/marcuslonnberg/sbt-docker
https://github.com/sbt/sbt-native-packager
http://trustmeiamadeveloper.com/2016/03/18/where-
is-my-memory-java/
https://www.playframework.com/documentation/2.6.x/
the-sbt-assembly-plugin
http://www.pointsoftware.ch/wp-
content/uploads/2012/10/JUtH_20121024_RuntimeData