Docker Hub Automated builds do not cache layers

[CL0SeY]

Builds are slower on Docker Hub compared to building the same Dockerfile on a static same host. This is especially evident if bringing in a large number of dependencies (e.g. node npm install).

It would be good if layers from previous build could be re-used across runs. This would reduce the amount of CPU time builds take, and reduce bandwidth requirements.

[KonstantinSchubert]

I suspect that this is partially a feature, not a bug.

Consider a layer such as

RUN apt update

If you build this locally, you will notice that this layer gets cached. But the command is non-deterministic. After a couple of days, you do NOT want to cache this any longer, because you want your images to include the newer, more up-to-date package lists.

Locally, it is not a problem. You just tell docker build not to cache this time. For automated builds on docker hub, you would need a way to specify how often the cache should get invalidated.

I presume that the developers of Dockerhub did not want to deal with such problems and therefore decided to simply never cache.

I agree that it is annoying, though :)

[amcsi]

It takes me 15 minutes after every little push for my project to be built, because the node npm packages keep getting installed from scratch over and over again. So I take it I should stop using Docker Hub and created builds myself manually if I wanted layers to be cached :(

[SergeyKapshuchenko]

still not caching layers ?