update(rule_loader): deprecate all non-SemVer compatible values

Signed-off-by: Andrea Terzolo <andreaterzolo3@gmail.com>

unit_tests/engine/test_rule_loader.cpp

@@ -549,3 +549,57 @@ TEST_F(engine_loader_test, rewrite_rule)
 	auto rule_description = m_engine->describe_rule(&rule_name, {});
 	ASSERT_EQ(rule_description["rules"][0]["details"]["condition_compiled"].template get<std::string>(), "proc.name = cat");
 }
+
+TEST_F(engine_loader_test, required_engine_version_semver)
+{
+    std::string rules_content = R"END(
+- required_engine_version: 0.26.0
+
+- rule: test_rule
+  desc: test rule description
+  condition: evt.type = close
+  output: user=%user.name command=%proc.cmdline file=%fd.name
+  priority: INFO
+  enabled: false
+
+)END";
+
+	ASSERT_TRUE(load_rules(rules_content, "rules.yaml"));
+	ASSERT_FALSE(has_warnings());
+}
+
+TEST_F(engine_loader_test, required_engine_version_not_semver)
+{
+    std::string rules_content = R"END(
+- required_engine_version: 26
+
+- rule: test_rule
+  desc: test rule description
+  condition: evt.type = close
+  output: user=%user.name command=%proc.cmdline file=%fd.name
+  priority: INFO
+  enabled: false
+
+)END";
+
+	ASSERT_TRUE(load_rules(rules_content, "rules.yaml"));
+	ASSERT_TRUE(check_warning_message(WARNING_ENGINE_VERSION_NOT_SEMVER));
+}
+
+TEST_F(engine_loader_test, required_engine_version_invalid)
+{
+    std::string rules_content = R"END(
+- required_engine_version: seven
+
+- rule: test_rule
+  desc: test rule description
+  condition: evt.type = close
+  output: user=%user.name command=%proc.cmdline file=%fd.name
+  priority: INFO
+  enabled: false
+
+)END";
+
+	ASSERT_FALSE(load_rules(rules_content, "rules.yaml"));
+	ASSERT_TRUE(check_error_message("Unable to parse engine version"));
+}

userspace/engine/rule_loader_reader.cpp

@@ -368,6 +368,7 @@ static void read_item(
 
 			// Build proper semver representation
 			v.version = rule_loader::reader::get_implicit_engine_version(ver);
+			cfg.res->add_warning(falco::load_result::LOAD_DEPRECATED_ITEM, WARNING_ENGINE_VERSION_NOT_SEMVER, ctx);
 		} 
 		catch(std::exception& e)
 		{

userspace/engine/rule_loader_reader.h

@@ -32,6 +32,9 @@ limitations under the License.
 // Warning message used when `enabled` is used without override.
 #define WARNING_ENABLED_MESSAGE "The standalone 'enabled' key usage is deprecated. The correct approach requires also a 'replace' entry under the 'override' key (i.e. 'enabled: replace')."
 
+// Warning message used when the `required_engine_version` is not semver compatible.
+#define WARNING_ENGINE_VERSION_NOT_SEMVER "The 'required_engine_version' should be SemVer compatible. All non-SemVer compatible values are deprecated."
+
 namespace rule_loader
 {