Fix issue where autodiscover hints default configuration was not being copied. (#16987) (#17002)

* Fix issue where autodiscover hints default configuration was not being copied.

* Add changelog.

* Add test and update comment.

(cherry picked from commit 661ff14)

Author: blakerouse

CHANGELOG.next.asciidoc

@@ -119,6 +119,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Adding the var definitions in azure manifest files, fix for errors when executing command setup. {issue}16270[16270] {pull}16468[16468]
 - Fix merging of fileset inputs to replace paths and append processors. {pull}16450{16450}
 - Add queue_url definition in manifest file for aws module. {pull}16640{16640}
+- Fix issue where autodiscover hints default configuration was not being copied. {pull}16987[16987]
 
 *Heartbeat*
 

filebeat/autodiscover/builder/hints/config.go

@@ -58,8 +58,9 @@ func (c *config) Unpack(from *common.Config) error {
 				return nil
 			}
 		} else {
-			// full config provided, discard default
-			c.DefaultConfig = config
+			// full config provided, discard default. It must be a clone of the
+			// given config otherwise it could be updated across multiple inputs.
+			c.DefaultConfig = common.MustNewConfigFrom(config)
 		}
 	}
 

filebeat/autodiscover/builder/hints/config_test.go

@@ -0,0 +1,45 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package hints
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/elastic/beats/v7/libbeat/common"
+)
+
+func TestUnpackCopiesDefault(t *testing.T) {
+	userCfg := common.MustNewConfigFrom(common.MapStr{
+		"default_config": common.MapStr{
+			"type": "container",
+			"paths": []string{
+				"/var/log/containers/*${data.kubernetes.container.id}.log",
+			},
+		},
+	})
+
+	cfg1 := defaultConfig()
+	assert.NoError(t, userCfg.Unpack(&cfg1))
+
+	cfg2 := defaultConfig()
+	assert.NoError(t, userCfg.Unpack(&cfg2))
+
+	assert.NotEqual(t, cfg1.DefaultConfig, cfg2.DefaultConfig)
+}