Java & containers: what I wish I knew before I have used it

They told you that using Java with containers were great, but they never mentioned that wouldn't be that easy, right?
You really got all advantages of containers like isolation, scalability, ease of deployment, and version management, but what about the pitfalls when using it with Java? Memory management, image size, initialization time… sometimes they can be tricky!
But there's a way out! Luckily there are have some best practices that will rescue your application from failing. From the Dockerfile to the Java updates (from 9 to 14 and beyond), you can have the best of both worlds right on your hands.
Join this practical session and transform the way you deal with Java and containers. Today.

Transcript

1. Java & containers: what I wish I knew before I used it Elder Moraes Developer Advocate @elderjava
2. @elderjava 2 Photo by Andy Li on Unsplash
3. @elderjava 3 Source: https://www.bricoleurbanism.org/whimsicality/personal-container-management/
4. @elderjava 4 eldermoraes.com/join Java Champion Developer Advocate at Red Hat Board member at SouJava Author of Jakarta EE Cookbook Helps Java developers to build and deliver awesome application so they can work on great projects
5. @elderjava 5 Common Issues when combining Java & containers • Long build time • Huge image size • Hard maintainability • Resources allocation
6. @elderjava 6 https://github.com/eldermoraes/java_and_containers
7. @elderjava 7 Long build time How to avoid
8. @elderjava 8 Mind order for caching Do this Avoid this
9. @elderjava 9 Be specific for caching Do this Avoid this
10. @elderjava 10 Group units for caching Do this Avoid this
11. @elderjava 11 Huge image size How to get rid of
12. @elderjava 12 Mind unnecessary dependencies Avoid this Do this
13. @elderjava 13 Eliminate package manager cache Avoid this Do this
14. @elderjava 14 Choose minimal size images SIZE REPOSITORY TAG
15. @elderjava 15 Use optimized tools/frameworks
16. @elderjava 16 Hard maintainability How to stay away from
17. @elderjava 17 Use official images Avoid this Do this
18. @elderjava 18 Be specific with tags Avoid this Do this
19. @elderjava 19 Reference https://www.docker.com/blog/intro-guide-to- dockerfile-best-practices/
20. @elderjava 20 Resources allocation How to manage
21. @elderjava 21 For Java 8u121 and before Container? cgroups?
22. @elderjava 22 For Java 8u121 and before "Control groups (cgroups) is a kernel feature that limits, accounts for and isolates the CPU, memory, disk I/O and network's usage of one or more processes." Source: https://www.linuxjournal.com/content/everything-you-need-know-about-linux-containers-part-i-linux-control-groups-and-process
23. @elderjava 23 For Java 8u121 and before https://github.com/fabric8io-images/run-java-sh
24. @elderjava 24 For Java 8u131 and Java 9 • ParallelGCThreads: helps to limit the cpu usage of a container • UseCGroupMemoryLimitForHeap: JVM uses the cgroups limits to calculate memory defaults • MaxRAMFraction: percentage of available RAM that can be used
25. @elderjava 25 For Java 8u191 and Java 10 • InitialRAMPercentage: initial percentage of heap allocation • MaxRAMPercentage: maximum percentage of heap allocation • MinRAMPercentage: minimum percentage of heap allocation • # of CPUs is calculated from container allocation by default (JDK-8196595)
26. @elderjava 26 For Java 11 • -XshowSettings (Container Metrics): display the system or container configuration • JDK-8197867: improve CPU calculations for both containers and JVM hotspot (see PreferContainerQuotaForCPUCount)
27. @elderjava 27 For Java 12 and 13 • jhsdb now can be attached to Java processes running in containers (JDK-8205992) • Container support improved for Java Flight Recorder (JDK-8203359) • Improve systemd slice memory limit support (JDK-8217338)
28. @elderjava 28 For Java 14 • JFR Event Streaming: expose JDK Flight Recorder data for continuous monitoring (easier for observability in clusters) • Packaging Tool: tool for packaging self-contained Java applications (incubator)
29. @elderjava 29 Conclusions • Yes, Java and containers can get along! • Be intentional when building your Dockerfiles • Better start with Java 11+ • If you *really* need 8 (why?), be extra cautious
30. @elderjava 30 developer.redhat.com