Use custom error

filebeat/fileset/pipelines.go

@@ -39,6 +39,25 @@ type PipelineLoader interface {
 	GetVersion() common.Version
 }
 
+// MultiplePipelineUnsupportedError is an error returned when a fileset uses multiple pipelines but is
+// running against a version of Elasticsearch that doesn't support this feature.
+type MultiplePipelineUnsupportedError struct {
+	module               string
+	fileset              string
+	esVersion            common.Version
+	minESVersionRequired common.Version
+}
+
+func (m MultiplePipelineUnsupportedError) Error() string {
+	return fmt.Sprintf(
+		"the %s/%s fileset has multiple pipelines, which are only supported with Elasticsearch >= %s. Currently running with Elasticsearch version %s",
+		m.module,
+		m.fileset,
+		m.minESVersionRequired.String(),
+		m.esVersion.String(),
+	)
+}
+
 // LoadPipelines loads the pipelines for each configured fileset.
 func (reg *ModuleRegistry) LoadPipelines(esClient PipelineLoader, overwrite bool) error {
 	for module, filesets := range reg.registry {
@@ -62,7 +81,7 @@ func (reg *ModuleRegistry) LoadPipelines(esClient PipelineLoader, overwrite bool
 			esVersion := esClient.GetVersion()
 			minESVersionRequired := common.MustNewVersion("6.5.0")
 			if len(pipelines) > 1 && esVersion.LessThan(minESVersionRequired) {
-				return fmt.Errorf("the %s/%s fileset has multiple pipelines, which are only supported with Elasticsearch >= %s. Currently running with Elasticsearch version %s", module, name, minESVersionRequired.String(), esVersion.String())
+				return MultiplePipelineUnsupportedError{module, name, esVersion, *minESVersionRequired}
 			}
 
 			var pipelineIDsLoaded []string

filebeat/fileset/pipelines_test.go

@@ -31,24 +31,24 @@ import (
 
 func TestLoadPipelinesWithMultiPipelineFileset(t *testing.T) {
 	cases := []struct {
-		name        string
-		esVersion   string
-		expectedErr string
+		name          string
+		esVersion     string
+		isErrExpected bool
 	}{
 		{
-			name:        "ES < 6.5.0",
-			esVersion:   "6.4.1",
-			expectedErr: "the mod/fls fileset has multiple pipelines, which are only supported with Elasticsearch >= 6.5.0. Currently running with Elasticsearch version 6.4.1",
+			name:          "ES < 6.5.0",
+			esVersion:     "6.4.1",
+			isErrExpected: true,
 		},
 		{
-			name:        "ES == 6.5.0",
-			esVersion:   "6.5.0",
-			expectedErr: "",
+			name:          "ES == 6.5.0",
+			esVersion:     "6.5.0",
+			isErrExpected: false,
 		},
 		{
-			name:        "ES > 6.5.0",
-			esVersion:   "6.6.0",
-			expectedErr: "",
+			name:          "ES > 6.5.0",
+			esVersion:     "6.6.0",
+			isErrExpected: false,
 		},
 	}
 
@@ -95,10 +95,10 @@ func TestLoadPipelinesWithMultiPipelineFileset(t *testing.T) {
 			assert.NoError(t, err)
 
 			err = testRegistry.LoadPipelines(testESClient, false)
-			if test.expectedErr == "" {
-				assert.NoError(t, err)
+			if test.isErrExpected {
+				assert.IsType(t, MultiplePipelineUnsupportedError{}, err)
 			} else {
-				assert.Error(t, err, test.expectedErr)
+				assert.NoError(t, err)
 			}
 		})
 	}