Dynamically skip builds on Travis CI?

[PeterDaveHello]

As we start to send pull requests to Docker official images automatically, and the process will detect if Dockerfiles are touched or not, then decide to send the pull request or not, maybe we can use the same method to directly return 0 on Travis CI to skip those Docker builds to save tons of time for those pull requests didn't revised Dockerfiles?

[PeterDaveHello]

cc @LaurentGoderre

[LaurentGoderre]

Not sure if it's something we should care about but the tags we are using as bas image are not immutable and get updates. There might be value in building all images when one of them changes. However, is the way the official images repo handles those enough for us and does the "benefit" of building everything outweigh the cost of those long builds.....

[PeterDaveHello]

For the cases that we didn't change any Dockerfiles, it should do the benefit, right?

[LaurentGoderre]

Yeah I think we can skip the build if we didn't touch any Dockefile

[PeterDaveHello]

I'll be unavailable to write this part right now, feel free to send a PR if anyone wants to ;)