Add support for .dockerignore

[brutasse]

Fixes #265.

Implementation is a bit more elaborate than docker's implementation and matches with the one proposed in moby/moby#6869 to handle permission issues more nicely.

[shin-]

Awesome, thanks! Do you think you could add some unit tests?

[brutasse]

@shin- I just added an integration test

[brutasse]

Is there anything else that needs to be done to help getting this merged?

[shin-]

Hey, sorry for the late response, I was MIA for a week and didn't get a chance to check back.

I'd be interested in a couple unit tests for the utils.tar function specifically with different exclude values, and checking that the resulting excludes the expected files (i.e. by listing the tarfile contents). Do you think that's something you could add? That way if we introduce a bug in the future it would be caught by the CI immediately (whereas integration tests are only run manually).

Thanks a ton for the work you've done so far!

[brutasse]

@shin- done. I've added a unit test for utils.tar that validates a couple of scenarios. In addition:

• Some tests were leaking temp dirs, I added a couple of addCleanup calls to properly delete them
• Python 2.6 doesn't have addCleanup() so I added an implementation for 2.6 that's loosely similar to what unittest does in Python >= 2.7

Let me know if anything else is needed.

[shin-]

Great, thanks a lot! Merging =)

[hamiltont]

Thanks a lot @brutasse and @shin- !

[brutasse]

✨ 🍰 🤘