In a blog post about creating a dockerized development environment there is a section where the following question and first paragraph answer are given:
What type of build artifacts do you want?
The build artifact I wanted in this example was a running container. Either Compose or docker would have been appropriate tools to that end. In your scenario you might prefer to have a distributable image, or you might prefer that the build produce a binary on your host operating system.
I read in another question that an artifact can be anything created during a process. From reading through other answers it seems like the context in which the term is used is important.
In the context of using Docker to create a development environment, what does build artifact mean?
Environment + Compiled output = Artifact.That is, the full environment including all tools, dependencies etc. needed to build the source (image), + the actually built/compiled result (runnables/libs), with the latter stored inside the former!
This way, in case of a crash/bug, everything is there for you, ready to be debugged no matter what dusty & old version of your software the issue occurred on. *
*: I didn't include source in above description, but that could also be preferable. Otherwise, since we all use version control, it can be mounted afterwards if necessary.
(note from comments)
"Artifact" is merely a word for something that is produced; in this context a byproduct when developing software. So the runnables/libs are the artifact(s) produced when compiling source, and the image is the artifact produced by the whole "build"-step, basically an artifact containing one or more other artifact(s)!
This makes more sense when you start working with automated build, test & deployment pipelines (AKA Continuous Delivery).
Note 1:
This would be the end-result, thus how you choose to setup any steps up until this point is up to you (split-image approach etc.).
Note 2:
I've just recently started playing with docker in combination with continuous delivery, so these are just my initial two cents :)
In terms of build pipelines in general the Artifact is the software component that is produced during the build, stored in a repository and ultimately deployed into your different environments.
For non-dockerized Java applications this is typically a JAR/WAR. For dockerized applications this is typically an image that contains the JAR/WAR.