Inconsistent outputs due to timezone

[benjaminRomano]

Background
I'm seeing cache misses due to the kotlin jars have different file timestamps. It appears, the kotlin rules depend on the system default timezone which may not be consistent across machines.

Suggested Fix
It seems that setting the timezone to "UTC" should resolve this issue, but I still saw inconsistencies in timestamps between CI and my local machine. I haven't had a chance to debug further, but one thing I was doing differently was depending on kotlin rules using git_repository instead of building the release artifact.

Workaround
I'm able to workaround this issue by setting my machines timezone to match our CI builder's timezone UTC for the time being.

[davidsantiago]

It looks like there's an old PR (#167) that touches the same line you've identified, but it looks like they're solving the problem differently. Does this PR look like it would fix the issue for you?

[benjaminRomano]

Interesting. I found the original commit that introduced this change here. It seems including the timezone is intentional.

[davidsantiago]

Do I understand from your comment that you updated the code in rules_kotlin to specify UTC as the time zone and it still had inconsistencies? Or did you mean updating the timezone of your local machine?

[benjaminRomano]

Sorry for slow response. I updated the code to use a standard timezone, UTC; however, this was not the correct solution as it causes the timezone information to always be encoded within the zip.

I tracked down the root cause when investigating a similar issue within Bazel's android rules. The problem is JDK 8 appears to have a bug when using unix epoch. It will encode the system's timezone into the zip archive making it non-reproducible. There's a good explanation of the issue within Gradle's archiving source code: https://github.com/gradle/gradle/blob/master/subprojects/core/src/main/java/org/gradle/api/internal/file/archive/ZipCopyAction.java#L42-L56

[cgruber]

Fixed in #304