Docker & Java
This repo contains demo materials for:
- Tips minimize java containers images
- Tricks for fast startup java apps running in containrs
- gotchas and issues while running java apps in containers and the improvements that has been made
The repo is splitte into multiple branchs, each contains a specific topic. The
Dockerfiles uses the generated jar after running the build (
mvn clean package). The build step could be integrated in the provided
Dockerfiles, but it would slow the demoing the intetntion of this repo, so I kept it outside. Below branch details:
master: simple netty app, running in a container
mod: Using Project Jigsaw’s
jlink, that offers the ability to produce a minimal JRE based on the modules our application requires.
alpine: This uses the early access alpine build of java 13, based on project protola: the community effort to port java to
cdc: This showcase the class data sharing (CDS) feature. CDC offers dynamic sharing of data between multiple Java Virtual Machines (JVM), which helps to reduce the startup time and memory footprint.
aot: Using Ahead Of Time compilation. It compiles the bytecode such that it is completely static which should lead to the fastest startup and initial execution speed.
graal: This part uses graal VM to create native images for existing JVM-based applications.
sb: This branch contains a simple instructions to run the petclinic application and test how it behaves running inside a java 8 docker container, and java 11!
bench.sh run each container and print at the end the total size of the image + the time it takes for teh container to run! for me I named the images:
mod. I prefixed each of them with
dc! Executing the scripts shows below results in my machine:
Image size Startup aot 463.864MB 654 ms cdc 443.183MB 689 ms plain 425.875MB 740 ms mod 55.6048MB 686 ms graal 9.49464MB 78 ms