Use Docker's multi-stage builds to reduce image size

[Hazmi35]

Docker images is built up from a series of layers. Each layer represents an instruction in the image’s Dockerfile. Meaning every instructions in the image's Dockerfile will have it's own layer, and will still exists on the final image.

I see that in line 20 on original Dockerfile, you are removing some dirty stuffs from gradle for runtime, that's good, but what you don't know that there is still a leftover in /root/.gradle, you could also remove it manually using rm but using multi-stage like this is more proper/better or you can say clean

With multi-stage builds, every dirty stuffs while compiling will not go into the final image, so no need to delete /root/.gradle or even /tmp/*, so with that, this PR will reduce image size from 514MB to 232MB

Old image layers:

New image layers:

And, on the final layer of new image:

[akbaryahya]

interesting, I just realized there is something left in root folder, I will try to finish #2 first and tonight I will make an image.
once again thank you

[Hazmi35]

Just rebased with main branch, this PR is ready

[Hazmi35]

interesting, I just realized there is something left in root folder, I will try to finish #2 first and tonight I will make an image. once again thank you

Why not build the image in GitHub Actions?

[akbaryahya]

actually i want to use it but i still don't know how to use it and when it was v1.0 it was too big so i thought it was not enough :/