cherry-pick: Separate front- and back- end builds

Merge in DNS/adguard-home from imp-bamboo-specs to master

Squashed commit of the following:

commit 3415b650e48aefef3ad16030be3d797de4015403
Merge: e37c0a2b f58265ec
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Mon Aug 15 18:42:42 2022 +0300

    Merge branch 'master' into imp-bamboo-specs

commit e37c0a2bb52fab98e133332e8f54d500d0f96b06
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Aug 15 18:30:33 2022 +0300

    scripts: replace find with loop

commit 826a02f6a11000cce4b3205229d6bbb050c8dd73
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Mon Aug 15 18:00:41 2022 +0300

    all: ...again

commit 54aebf5d4aeba35e3dc320436236759f4d1ccdad
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Mon Aug 15 17:59:24 2022 +0300

    all: fix spec yaml

commit 87b92b30504f2427c40303265354afba4855e0bb
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Mon Aug 15 17:48:19 2022 +0300

    all: separate front- and back-end builds

scripts/make/build-release.sh

@@ -109,17 +109,17 @@ log "checking tools"
 
 # Make sure we fail gracefully if one of the tools we need is missing.  Use
 # alternatives when available.
-sha256sum_cmd='sha256sum'
-for tool in gpg gzip sed "$sha256sum_cmd" snapcraft tar zip
+use_shasum='0'
+for tool in gpg gzip sed sha256sum snapcraft tar zip
 do
 	if ! command -v "$tool" > /dev/null
 	then
-		if [ "$tool" = "$sha256sum_cmd" ] && command -v 'shasum' > /dev/null
+		if [ "$tool" = 'sha256sum' ] && command -v 'shasum' > /dev/null
 		then
-			# macOS doesn't have sha256sum installed by default, but
-			# it does have shasum.
+			# macOS doesn't have sha256sum installed by default, but it does
+			# have shasum.
 			log 'replacing sha256sum with shasum -a 256'
-			sha256sum_cmd='shasum -a 256'
+			use_shasum='1'
 		else
 			log "pieces don't fit, '$tool' not found"
 
@@ -127,7 +127,7 @@ do
 		fi
 	fi
 done
-readonly sha256sum_cmd
+readonly use_shasum
 
 # Data section.  Arrange data into space-separated tables for read -r to read.
 # Use a hyphen for missing values.
@@ -332,15 +332,40 @@ log "$build_archive"
 
 log "calculating checksums"
 
+# calculate_checksums uses the previously detected SHA-256 tool to calculate
+# checksums.  Do not use find with -exec, since shasum requires arguments.
+calculate_checksums() {
+	if [ "$use_shasum" -eq '0' ]
+	then
+		sha256sum "$@"
+	else
+		shasum -a 256 "$@"
+	fi
+}
+
 # Calculate the checksums of the files in a subshell with a different working
 # directory.  Don't use ls, because files matching one of the patterns may be
 # absent, which will make ls return with a non-zero status code.
+#
+# TODO(a.garipov): Consider calculating these as the build goes.
 (
+	set +f
+
 	cd "./${dist}"
 
-	find . ! -name . -prune \( -name '*.tar.gz' -o -name '*.zip' \)\
-		-exec "$sha256sum_cmd" {} +\
-		> ./checksums.txt
+	: > ./checksums.txt
+
+	for archive in ./*.zip ./*.tar.gz
+	do
+		# Make sure that we don't try to calculate a checksum for a glob pattern
+		# that matched no files.
+		if [ ! -f "$archive" ]
+		then
+			continue
+		fi
+
+		calculate_checksums "$archive" >> ./checksums.txt
+	done
 )
 
 log "writing versions"