[Autodiscover] Handle input-not-finished errors in config reload

CHANGELOG.next.asciidoc

@@ -167,6 +167,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - [Metricbeat][Kubernetes] Change cluster_ip field from ip to keyword. {pull}20571[20571]
 - Rename cloud.provider `az` value to `azure` inside the add_cloud_metadata processor. {pull}20689[20689]
 - Add missing country_name geo field in `add_host_metadata` and `add_observer_metadata` processors. {issue}20796[20796] {pull}20811[20811]
+- [Autodiscover] Handle input-not-finished errors in config reload. {pull}20915[20915]
 
 *Auditbeat*
 

filebeat/input/log/input.go

@@ -175,7 +175,7 @@ func (p *Input) loadStates(states []file.State) error {
 
 			// In case a input is tried to be started with an unfinished state matching the glob pattern
 			if !state.Finished {
-				return &input.ErrInputNotFinished{State: state.String()}
+				return &common.ErrInputNotFinished{State: state.String()}
 			}
 
 			// Convert state to current identifier if different

filebeat/input/runnerfactory.go

@@ -59,7 +59,7 @@ func (r *RunnerFactory) Create(
 
 func (r *RunnerFactory) CheckConfig(cfg *common.Config) error {
 	_, err := r.Create(pipeline.NewNilPipeline(), cfg)
-	if _, ok := err.(*ErrInputNotFinished); ok {
+	if _, ok := err.(*common.ErrInputNotFinished); ok {
 		// error is related to state, and hence config can be considered valid
 		return nil
 	}

libbeat/cfgfile/list.go

@@ -92,7 +92,12 @@ func (r *RunnerList) Reload(configs []*reload.ConfigWithMeta) error {
 	for hash, config := range startList {
 		runner, err := createRunner(r.factory, r.pipeline, config)
 		if err != nil {
-			r.logger.Errorf("Error creating runner from config: %s", err)
+			if _, ok := err.(*common.ErrInputNotFinished); ok {
+				// error is related to state, we should not log at error level
+				r.logger.Debugf("Error creating runner from config: %s", err)
+			} else {
+				r.logger.Errorf("Error creating runner from config: %s", err)
+			}
 			errs = append(errs, errors.Wrap(err, "Error creating runner from config"))
 			continue
 		}

filebeat/input/errors.go → libbeat/common/errors.go

@@ -15,7 +15,7 @@
 // specific language governing permissions and limitations
 // under the License.
 
-package input
+package common
 
 import (
 	"fmt"