[PATCH v2] tag: add tag.gpgSign config option to force all tags be GPG-signed

[Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>]

As may CI/CD tools don't allow to control command line options when
executing `git tag` command, a default value in the configuration file
will allow to enforce tag signing if required.

The new config-file option tag.gpgSign enforces signed tags. Additional
command line option --no-gpg-sign is added to disable such behavior if
needed. E.g.:

    $ git tag -m "commit message"

will generate a GPG signed tag if tag.gpgSign option is true, while

    $ git tag --no-gpg-sign -m "commit message"

will skip the signing step.

Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
---
 Documentation/git-tag.txt |  7 +++++++
 builtin/tag.c             | 18 +++++++++++++++---
 t/t7004-tag.sh            | 21 +++++++++++++++++++++
 3 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-tag.txt b/Documentation/git-tag.txt
index a74e7b926d..d9dbfb4e37 100644
--- a/Documentation/git-tag.txt
+++ b/Documentation/git-tag.txt
@@ -64,6 +64,9 @@ OPTIONS
 -s::
 --sign::
 	Make a GPG-signed tag, using the default e-mail address's key.
+	The default behabior of tag GPG-signing controlled by `tag.gpgSign`
+	configuration variable if it exists, or disabled oder otherwise.
+	See linkgit:git-config[1].
 
 -u <keyid>::
 --local-user=<keyid>::
@@ -193,6 +196,10 @@ This option is only applicable when listing tags without annotation lines.
 	that of linkgit:git-for-each-ref[1].  When unspecified,
 	defaults to `%(refname:strip=2)`.
 
+--no-gpg-sign::
+	Countermand `tag.gpgSign` configuration variable that is
+	set to force each and every tag to be signed.
+
 <tagname>::
 	The name of the tag to create, delete, or describe.
 	The new tag name must pass all checks defined by
diff --git a/builtin/tag.c b/builtin/tag.c
index ef37dccf86..7f9aef4840 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -33,6 +33,7 @@ static const char * const git_tag_usage[] = {
 
 static unsigned int colopts;
 static int force_sign_annotate;
+static int sign_tag;
 
 static int list_tags(struct ref_filter *filter, struct ref_sorting *sorting,
 		     struct ref_format *format)
@@ -144,6 +145,11 @@ static int git_tag_config(const char *var, const char *value, void *cb)
 	int status;
 	struct ref_sorting **sorting_tail = (struct ref_sorting **)cb;
 
+	if (!strcmp(var, "tag.gpgsign")) {
+		sign_tag = git_config_bool(var, value);
+		return 0;
+	}
+
 	if (!strcmp(var, "tag.sort")) {
 		if (!value)
 			return config_error_nonbool(var);
@@ -392,6 +398,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 	struct ref_format format = REF_FORMAT_INIT;
 	int icase = 0;
 	int edit_flag = 0;
+	int no_gpg_sign = 0;
 	struct option options[] = {
 		OPT_CMDMODE('l', "list", &cmdmode, N_("list tag names"), 'l'),
 		{ OPTION_INTEGER, 'n', NULL, &filter.lines, N_("n"),
@@ -413,6 +420,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 					N_("use another key to sign the tag")),
 		OPT__FORCE(&force, N_("replace the tag if exists"), 0),
 		OPT_BOOL(0, "create-reflog", &create_reflog, N_("create a reflog")),
+		OPT_BOOL(0, "no-gpg-sign", &no_gpg_sign, N_("do not GPG-sign tag")),
 
 		OPT_GROUP(N_("Tag listing options")),
 		OPT_COLUMN(0, "column", &colopts, N_("show tag list in columns")),
@@ -445,6 +453,10 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 
 	argc = parse_options(argc, argv, prefix, options, git_tag_usage, 0);
 
+	if (no_gpg_sign) {
+		sign_tag = 0;
+	}
+
 	if (keyid) {
 		opt.sign = 1;
 		set_signing_key(keyid);
@@ -463,7 +475,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 	if (cmdmode == 'l')
 		setup_auto_pager("tag", 1);
 
-	if ((create_tag_object || force) && (cmdmode != 0))
+	if ((create_tag_object || force || no_gpg_sign) && (cmdmode != 0))
 		usage_with_options(git_tag_usage, options);
 
 	finalize_colopts(&colopts, -1);
@@ -556,8 +568,8 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 
 	create_reflog_msg(&object, &reflog_msg);
 
-	if (create_tag_object) {
-		if (force_sign_annotate && !annotate)
+	if (create_tag_object || sign_tag) {
+		if (sign_tag || (force_sign_annotate && !annotate))
 			opt.sign = 1;
 		create_tag(&object, object_ref, tag, &buf, &opt, &prev, &object);
 	}
diff --git a/t/t7004-tag.sh b/t/t7004-tag.sh
index 6aeeb279a0..98a07a29d2 100755
--- a/t/t7004-tag.sh
+++ b/t/t7004-tag.sh
@@ -932,6 +932,27 @@ test_expect_success GPG \
 	test_cmp expect actual
 '
 
+get_tag_header gpgsign-enabled $commit commit $time >expect
+echo "A message" >>expect
+echo '-----BEGIN PGP SIGNATURE-----' >>expect
+test_expect_success GPG \
+	'git tag configured tag.gpgsign enables GPG sign' \
+	'test_config tag.gpgsign true &&
+	git tag -m "A message" gpgsign-enabled &&
+	get_tag_msg gpgsign-enabled>actual &&
+	test_cmp expect actual
+'
+
+get_tag_header no-gpg-sign $commit commit $time >expect
+echo "A message" >>expect
+test_expect_success GPG \
+	'git tag --no-gpg-sign configured tag.gpgsign skip GPG sign' \
+	'test_config tag.gpgsign true &&
+	git tag -a --no-gpg-sign -m "A message" no-gpg-sign &&
+	get_tag_msg no-gpg-sign>actual &&
+	test_cmp expect actual
+'
+
 test_expect_success GPG \
 	'trying to create a signed tag with non-existing -F file should fail' '
 	! test -f nonexistingfile &&
-- 
2.21.0