By Terry Goss, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=1561215

Things that go wrong when deploying Java with containers

Martin Lehmann

@theneva

FINN.no

(and how to avoid them)

Get to know your app!

App config confined to app repo
Easier to start apps locally and in CI
Higher dev/production parity
Automatic horisontal scaling
Overall improved performance at much lower cost

A tale of CPU and memory

OOMKilled!

CPU request = 1 core
Memory request = 1G
Memory limit = 1,3G
Max heap size = 0,6 * Limit = 0,78

requestParams.parallelStream()
  .map(…)

Have you ever used…

Thread pooling <3 72 CPUs

Java >= 8u131

(April 2017)

```
-XX:+UnlockExperimentalVMOptions
```
```
-XX:+UseCGroupMemoryLimitForHeap
```

By Chagai at English Wikipedia - Transferred from en.wikipedia to Commons., Public Domain, https://commons.wikimedia.org/w/index.php?curid=3839230

By maix - Based on blank map of Europe.svg, source: Time zones of Europe.png;, CC SA 1.0, https://commons.wikimedia.org/w/index.php?curid=1641488

UTC is great!
Except when locales aren't configured

What can we do?

Know your app before you run it!

(How) do you need to tune the JVM?
Do you have anything that scales by CPUs?
Which resources does your app really need?
Make it easy to do the right thing!

Help your developers!

FROM <container registry>/finntech/java8:8

ENV LC_ALL "no_NB.UTF-8"
ENV LANG "no_NB.UTF-8"
ENV TZ "Europe/Oslo"

ENV JAVA_OPTS -DLog4jContextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector

COPY build/libs/ad-input-server-*.war /app

https://github.com/fabric8io-images/java

FiaaS

https://github.com/fiaas/fiaas-deploy-daemon

So: avoid great white sharks by…

Knowing your app's requirements and dependencies!
Making it easy to do the right thing
Expecting failure, and enabling easy rollback