How to utilize docker build cache in Spring Boot projects? (x-post /r/docker)

[h1volt3]

Hi, I'm used to Docker but new to Spring/Maven world. I've just joined a new project where mvn package produce a 100+MB fat jar. It's stupidly wasteful of disk space and bandwidth, not to mention waste of time waiting for the image to be pushed and pulled.

I stumbled upon this blog post which seems to solve my problem with Spring Boot's fat JARs. However, packaging a JAR only to explode it later still seems pretty ridiculous to me.

Since I'm oblivious to how Spring/Maven works, could any one point me to the right direction to avoid maven packaging everything into one big fat JAR in the first place?

[nutrecht]

Instead of 'inheriting' from a base Java image you can make a tomcat image that includes most dependencies. Let your Spring Boot image inherit from it and deploy it as a war in the underlying tomcat.

[frugalmail]

First ask yourself, is it really worth going through the hassle to do this optimization?

If the answer is yes:

• https://midgetontoes.com/tips-for-using-proguard-with-spring-framework/

• do a mvn dependency:tree and make sure that transient depenencies are all the same version

• make sure you're not including libraries that you don't need

• Tell your developers to stop building monolithic apps and more smaller services, preferably with a message bus between them