From 1402145cdd169aede0bdc51ff025abe05a6a1a53 Mon Sep 17 00:00:00 2001
From: Ainar Garipov <a.garipov@adguard.com>
Date: Fri, 30 Apr 2021 19:51:23 +0300
Subject: [PATCH] Pull request: all: improve build reproducibility

Updates #2959.

Squashed commit of the following:

commit 2178c73835454b75b6b0790322df3975e1d14f10
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Apr 30 19:34:39 2021 +0300

    all: improve build reproducibility
---
 scripts/README.md        |  4 +++-
 scripts/make/go-build.sh | 14 +++++++-------
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/scripts/README.md b/scripts/README.md
index 68831ab6..d6ad3ada 100644
--- a/scripts/README.md
+++ b/scripts/README.md
@@ -65,7 +65,7 @@ Optional environment:
     verbosity level `2` in `go-build.sh`, set this to `3` when calling
     `build-release.sh`.
  *  `VERSION`: release version.  Will be set by `version.sh` if it is unset or
-    it has the default `Makefile` value of `v0.0.0`.
+    if it has the default `Makefile` value of `v0.0.0`.
 
  ###  `clean.sh`: Cleanup
 
@@ -78,6 +78,8 @@ Required environment:
  ###  `go-build.sh`: Build The Backend
 
 Optional environment:
+ *  `BUILD_TIME`: If set, overrides the build time information.  Useful for
+    reproducible builds.
  *  `GOARM`: ARM processor options for the Go compiler.
  *  `GOMIPS`: ARM processor options for the Go compiler.
  *  `GO`: set an alternarive name for the Go compiler.
diff --git a/scripts/make/go-build.sh b/scripts/make/go-build.sh
index 610e9ab0..1f7bcc96 100644
--- a/scripts/make/go-build.sh
+++ b/scripts/make/go-build.sh
@@ -10,7 +10,7 @@
 # every package that is processed if the caller requested verbosity
 # level greater than 0.  Also show subcommands if the requested
 # verbosity level is greater than 1.  Otherwise, do nothing.
-verbose="${VERBOSE:-0}"
+readonly verbose="${VERBOSE:-0}"
 if [ "$verbose" -gt '1' ]
 then
 	env
@@ -33,10 +33,10 @@ fi
 set -e -f -u
 
 # Allow users to set the Go version.
-go="${GO:-go}"
+readonly go="${GO:-go}"
 
 # Require the channel to be set and validate the value.
-channel="$CHANNEL"
+readonly channel="$CHANNEL"
 case "$channel"
 in
 ('development'|'edge'|'beta'|'release')
@@ -52,10 +52,10 @@ esac
 # Require the version to be set.
 #
 # TODO(a.garipov): Additional validation?
-version="$VERSION"
+readonly version="$VERSION"
 
-# Set date and time of the current build.
-buildtime="$(date -u +%FT%TZ%z)"
+# Set date and time of the current build unless already set.
+readonly buildtime="${BUILD_TIME:-$( date -u +%FT%TZ%z )}"
 
 # Set the linker flags accordingly: set the release channel and the
 # current version as well as goarm and gomips variable values, if the
@@ -106,7 +106,7 @@ fi
 export CGO_ENABLED="$cgo_enabled"
 export GO111MODULE='on'
 
-readonly build_flags="${BUILD_FLAGS:-$race_flags $out_flags $par_flags $v_flags $x_flags}"
+readonly build_flags="${BUILD_FLAGS:-$race_flags --trimpath $out_flags $par_flags $v_flags $x_flags}"
 
 # Don't use quotes with flag variables to get word splitting.
 "$go" generate $v_flags $x_flags ./main.go