minikube binaries differ for every build

[bmwiedemann]

BUG REPORT:

Environment: Linux

Minikube version : 0.27.0

• OS : openSUSE-Tumbleweed

What happened:
When building the minikube openSUSE package, there are differences between every build.

build-compare's pkg-diff reports:

/usr/bin/minikube differs in ELF section .rodata
@@ -259384,10 +259384,10 @@
  14d6330 00044000 00000000 00000000 00000000  ..@.............
  14d6340 2f757372 2f6c6962 36342f67 6f2f312e  /usr/lib64/go/1.
  14d6350 31300000 00000000 00000000 00000000  10..............
- 14d6360 32303138 2d30372d 32315430 363a3532  2018-07-21T06:52
- 14d6370 3a33335a 00000000 00000000 00000000  :33Z............
- 14d6380 32303138 2d30372d 32315430 363a3532  2018-07-21T06:52
- 14d6390 3a33335a 00000000 00000000 00000000  :33Z............
+ 14d6360 32303138 2d30372d 32315430 363a3533  2018-07-21T06:53
+ 14d6370 3a35355a 00000000 00000000 00000000  :55Z............
+ 14d6380 32303138 2d30372d 32315430 363a3533  2018-07-21T06:53
+ 14d6390 3a35355a 00000000 00000000 00000000  :55Z............

What you expected to happen:
The build process should produce bit-identical binaries. E.g. use the $SOURCE_DATE_EPOCH environment variable instead of the current date as documented in
https://wiki.debian.org/ReproducibleBuilds/TimestampsProposal#Go

How to reproduce it (as minimally and precisely as possible):

osc checkout openSUSE:Factory/minikube
cd $_
osc build

[dlorenc]

Hmm, looks like this is coming from the build date we inject here: https://github.com/kubernetes/minikube/blob/master/hack/get_k8s_version.py#L65

Are you interested in changing this up? I'm not quite sure what the best general fix is.