Pull request: all: switch to SOURCE_DATE_EPOCH for source date

Closes #4221.

Squashed commit of the following:

commit c84a5699280cf4c0b1c2ed034a44f05ffc74d30d
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Feb 1 21:13:30 2022 +0300

    all: switch to SOURCE_DATE_EPOCH for source date

CHANGELOG.md

@@ -21,6 +21,11 @@ and this project adheres to
 
 ### Changed
 
+- Instead of adding the build time information, the build scripts now use the
+  standardized environment variable [`SOURCE_DATE_EPOCH`][repr] to add the date
+  of the commit from which the binary was built ([#4221]).  This should simplify
+  reproducible builds for package maintainers and those who compile their own
+  AdGuard Home.
 - The setting `local_domain_name` is now in the `dhcp` block in the
   configuration file to avoid confusion ([#3367]).
 - The `dns.bogus_nxdomain` configuration file parameter now supports CIDR
@@ -74,6 +79,9 @@ In this release, the schema version has changed from 12 to 13.
 [#2993]: https://github.com/AdguardTeam/AdGuardHome/issues/2993
 [#3057]: https://github.com/AdguardTeam/AdGuardHome/issues/3057
 [#3367]: https://github.com/AdguardTeam/AdGuardHome/issues/3367
+[#4221]: https://github.com/AdguardTeam/AdGuardHome/issues/4221
+
+[repr]: https://reproducible-builds.org/docs/source-date-epoch/
 
 
 

internal/version/version.go

@@ -7,6 +7,7 @@ import (
 	"runtime/debug"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/AdguardTeam/golibs/stringutil"
 )
@@ -30,7 +31,7 @@ var (
 	goarm      string
 	gomips     string
 	version    string
-	buildtime string
+	committime string
 )
 
 // Channel returns the current AdGuard Home release channel.
@@ -106,7 +107,7 @@ const (
 	vFmtVerHdr    = "Version: "
 	vFmtChanHdr   = "Channel: "
 	vFmtGoHdr     = "Go version: "
-	vFmtTimeHdr   = "Build time: "
+	vFmtTimeHdr   = "Commit time: "
 	vFmtRaceHdr   = "Race: "
 	vFmtGOOSHdr   = "GOOS: " + runtime.GOOS
 	vFmtGOARCHHdr = "GOARCH: " + runtime.GOARCH
@@ -148,15 +149,23 @@ func Verbose() (v string) {
 		vFmtGoHdr,
 		runtime.Version(),
 	)
-	if buildtime != "" {
-		stringutil.WriteToBuilder(b, nl, vFmtTimeHdr, buildtime)
+
+	if committime != "" {
+		commitTimeUnix, err := strconv.ParseInt(committime, 10, 64)
+		if err != nil {
+			stringutil.WriteToBuilder(b, nl, vFmtTimeHdr, fmt.Sprintf("parse error: %s", err))
+		} else {
+			stringutil.WriteToBuilder(b, nl, vFmtTimeHdr, time.Unix(commitTimeUnix, 0).String())
 		}
+	}
+
 	stringutil.WriteToBuilder(b, nl, vFmtGOOSHdr, nl, vFmtGOARCHHdr)
 	if goarm != "" {
 		stringutil.WriteToBuilder(b, nl, vFmtGOARMHdr, "v", goarm)
 	} else if gomips != "" {
 		stringutil.WriteToBuilder(b, nl, vFmtGOMIPSHdr, gomips)
 	}
+
 	stringutil.WriteToBuilder(b, nl, vFmtRaceHdr, strconv.FormatBool(isRace))
 
 	info, ok := debug.ReadBuildInfo()

scripts/README.md

@@ -90,14 +90,15 @@ 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 alternative name for the Go compiler.
  *  `OUT`: output binary name.
  *  `PARALLELISM`: set the maximum number of concurrently run build commands
     (that is, compiler, linker, etc.).
+ *  `SOURCE_DATE_EPOCH`: the [standardized][repr] environment variable for the
+    Unix epoch time of the latest commit in the repository.  If set, overrides
+    the default obtained from Git.  Useful for reproducible builds.
  *  `VERBOSE`: verbosity level.  `1` shows every command that is run and every
     Go package that is processed.  `2` also shows subcommands and environment.
     The default value is `0`, don't be verbose.
@@ -107,6 +108,8 @@ Optional environment:
 Required environment:
  *  `CHANNEL`: release channel, see above.
 
+[repr]: https://reproducible-builds.org/docs/source-date-epoch/
+
 
 
  ###  `go-deps.sh`: Install Backend Dependencies

scripts/make/Dockerfile

@@ -5,16 +5,20 @@ FROM alpine:3.13
 ARG BUILD_DATE
 ARG VERSION
 ARG VCS_REF
-LABEL maintainer="AdGuard Team <devteam@adguard.com>" \
+
+LABEL\
+	maintainer="AdGuard Team <devteam@adguard.com>" \
+	org.opencontainers.image.authors="AdGuard Team <devteam@adguard.com>" \
 	org.opencontainers.image.created=$BUILD_DATE \
-  org.opencontainers.image.url="https://adguard.com/adguard-home.html" \
-  org.opencontainers.image.source="https://github.com/AdguardTeam/AdGuardHome" \
-  org.opencontainers.image.version=$VERSION \
-  org.opencontainers.image.revision=$VCS_REF \
-  org.opencontainers.image.vendor="AdGuard" \
-  org.opencontainers.image.title="AdGuard Home" \
 	org.opencontainers.image.description="Network-wide ads & trackers blocking DNS server" \
-  org.opencontainers.image.licenses="GPL-3.0"
+	org.opencontainers.image.documentation="https://github.com/AdguardTeam/AdGuardHome/wiki/" \
+	org.opencontainers.image.licenses="GPL-3.0" \
+	org.opencontainers.image.revision=$VCS_REF \
+	org.opencontainers.image.source="https://github.com/AdguardTeam/AdGuardHome" \
+	org.opencontainers.image.title="AdGuard Home" \
+	org.opencontainers.image.url="https://adguard.com/en/adguard-home/overview.html" \
+	org.opencontainers.image.vendor="AdGuard" \
+	org.opencontainers.image.version=$VERSION
 
 # Update certificates.
 RUN apk --no-cache --update add ca-certificates libcap tzdata && \

scripts/make/go-build.sh

@@ -65,9 +65,9 @@ then
 fi
 readonly version
 
-# Set date and time of the current build unless already set.
-buildtime="${BUILD_TIME:-$( date -u +%FT%TZ%z )}"
-readonly buildtime
+# Set date and time of the latest commit unless already set.
+committime="${SOURCE_DATE_EPOCH:-$( git log -1 --pretty=%ct )}"
+readonly committime
 
 # Set the linker flags accordingly: set the release channel and the current
 # version as well as goarm and gomips variable values, if the variables are set
@@ -78,7 +78,7 @@ readonly version_pkg
 ldflags="-s -w"
 ldflags="${ldflags} -X ${version_pkg}.version=${version}"
 ldflags="${ldflags} -X ${version_pkg}.channel=${channel}"
-ldflags="${ldflags} -X ${version_pkg}.buildtime=${buildtime}"
+ldflags="${ldflags} -X ${version_pkg}.committime=${committime}"
 if [ "${GOARM:-}" != '' ]
 then
 	ldflags="${ldflags} -X ${version_pkg}.goarm=${GOARM}"

scripts/make/version.sh

@@ -86,6 +86,7 @@ in
 	# minor release.  If the current commit is the new minor release,
 	# num_commits_since_minor is zero.
 	num_commits_since_minor="$( git rev-list "${last_minor_zero}..HEAD" | wc -l )"
+
 	# The output of darwin's implementation of wc needs to be trimmed from
 	# redundant spaces.
 	num_commits_since_minor="$( echo "$num_commits_since_minor" | tr -d '[:space:]' )"