@swiedenfeld I was about to merge it but then realized... if the app is long running, such cache may eventually explode and cause an OOM. Since the class is in core, we can use Guava's cache with TTL to prevent that.

@bsideup Good point. I was unaware it could be running long as I focused on its use in build step. There, the number of ignore patterns must be bounded by the lines in .dockerignore, isn't it? In which other dimensions can we expect it to grow?

For the TTL, do you suggest a reasonable time interval until cache entries expire?

@swiedenfeld there are a few usages of docker-java that run for hours, days or even months :D

Since it parses the user input, there is no guarantee that the set will be final, despite the relationship to "a few lines in .dockerignore.

For TTL, I'd suggest something like 1 hour. Alternatively, IIRC Guava can limit by the cache size, which may be another option (to limit it to 25Mb, or 10k patterns, or similar)

@swiedenfeld ping :)

pong :)
I'm still on this and already tried something. I am quite convinced it can work using a LoadingCache with expiration. Still I want to write a test for the expiration behaviour.

@swiedenfeld FYI I just changed some defaults and will merge as soon as CI is green :)
I appreciate the desire to contribute the tests, feel free to submit a follow up PR containing them 👍