version: Make builds deterministic by dropping build time

Before converting to the new `WithGoBuildInformation()` monitoring
option in the preceding commit we always exposed the build time. We have
stopped doing that now and instead only expose information that Go puts
into the binary itself.

As a result, we can now drop the infrastructure to embed the build time
into the binary. This has the advantage that it significantly improves
incremental build times: previously we'd basically have to rebuild all
binaries every single time, as the embedded build time changes every
second. As we stop doing that we can in many cases skip this step. On my
machine this leads to a 3.5x build speedup.

    Benchmark 1: make
      Time (mean ± σ):     12.163 s ±  0.148 s    [User: 16.677 s, System: 3.496 s]
      Range (min … max):   12.044 s … 12.328 s    3 runs

    Benchmark 2: make GO_LDFLAGS=
      Time (mean ± σ):      3.469 s ±  0.060 s    [User: 5.593 s, System: 1.880 s]
      Range (min … max):    3.433 s …  3.539 s    3 runs

    Summary
      'make GO_LDFLAGS=' ran
        3.51 ± 0.07 times faster than 'make'

This has been benchmarked with the preceding commit which still embedded
the build time into the binary. By stubbing out the `GO_LDFLAGS`, which
is how we put the build time into the resulting binary, we are able to
emulate the new behaviour with this commit.

But besides the quality-of-life improvements for developers another
significant advantage is that we now have reproducible builds.

Changelog: fixed

1 files changed, 1 insertions, 9 deletions

diff --git a/internal/version/version.go b/internal/version/version.go
index 2d4fa67f3..a9db344bf 100644
--- a/internal/version/version.go
+++ b/internal/version/version.go
@@ -4,10 +4,7 @@ import (
 	"fmt"
 )
 
-var (
-	version   string
-	buildtime string
-)
+var version string
 
 // GetVersionString returns a standard version header
 func GetVersionString(binary string) string {
@@ -18,8 +15,3 @@ func GetVersionString(binary string) string {
 func GetVersion() string {
 	return version
 }
-
-// GetBuildTime returns the time at which the build took place
-func GetBuildTime() string {
-	return buildtime
-}