permit index-pattern only setup (elastic#7285) (elastic#7322)

with setup.dashboards.enabled=true, setup.dashboards.only_index=true always throws
"Error importing Kibana dashboards: fail to import the dashboards in Kibana"

(cherry picked from commit 4d678b4)

CHANGELOG.asciidoc

@@ -13,6 +13,8 @@ https://github.com/elastic/beats/compare/v6.3.0...6.3[Check the HEAD diff]
 
 *Affecting all Beats*
 
+- Allow index-pattern only setup when setup.dashboards.only_index=true. {pull}7285[7285]
+
 *Auditbeat*
 
 *Filebeat*

libbeat/dashboards/importer.go

@@ -278,8 +278,10 @@ func (imp Importer) ImportKibanaDir(dir string) error {
 	if !imp.cfg.OnlyDashboards {
 		check = append(check, "index-pattern")
 	}
+	wantDashboards := false
 	if !imp.cfg.OnlyIndex {
 		check = append(check, "dashboard")
+		wantDashboards = true
 	}
 
 	types := []string{}
@@ -306,7 +308,7 @@ func (imp Importer) ImportKibanaDir(dir string) error {
 		}
 	}
 
-	if !importDashboards {
+	if wantDashboards && !importDashboards {
 		return fmt.Errorf("No dashboards to import. Please make sure the %s directory contains a dashboard directory.",
 			dir)
 	}

libbeat/tests/system/test_dashboard.py

@@ -36,6 +36,32 @@ def test_load_dashboard(self):
 
         assert self.log_contains("Kibana dashboards successfully loaded") is True
 
+    @unittest.skipUnless(INTEGRATION_TESTS, "integration test")
+    @attr('integration')
+    def test_load_only_index_patterns(self):
+        """
+        Test loading dashboards
+        """
+        self.render_config_template()
+        beat = self.start_beat(
+            logging_args=["-e", "-d", "*"],
+            extra_args=["setup",
+                        "--dashboards",
+                        "-E", "setup.dashboards.file=" +
+                        os.path.join(self.beat_path, "tests", "files", "testbeat-dashboards.zip"),
+                        "-E", "setup.dashboards.beat=testbeat",
+                        "-E", "setup.dashboards.only_index=true",
+                        "-E", "setup.kibana.protocol=http",
+                        "-E", "setup.kibana.host=" + self.get_kibana_host(),
+                        "-E", "setup.kibana.port=" + self.get_kibana_port(),
+                        "-E", "output.elasticsearch.hosts=['" + self.get_host() + "']",
+                        "-E", "output.file.enabled=false"]
+        )
+
+        beat.check_wait(exit_code=0)
+
+        assert self.log_contains("Kibana dashboards successfully loaded") is True
+
     @unittest.skipUnless(INTEGRATION_TESTS, "integration test")
     @attr('integration')
     def test_export_dashboard(self):