feat(outputs.elasticsearch): Allow custom template index settings (#15471)

plugins/outputs/elasticsearch/README.md

@@ -328,6 +328,16 @@ to use them.
   # To pass custom HTTP headers please define it in a given below section
   # [outputs.elasticsearch.headers]
   #    "X-Custom-Header" = "custom-value"
+
+  ## Template Index Settings
+  ## Overrides the template settings.index section with any provided options.
+  ## Defaults provided here in the config
+  # template_index_settings = {
+  #   refresh_interval = "10s",
+  #   mapping.total_fields.limit = 5000,
+  #   auto_expand_replicas = "0-1",
+  #   codec = "best_compression"
+  # }
 ```
 
 ### Permissions

plugins/outputs/elasticsearch/elasticsearch.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"crypto/sha256"
 	_ "embed"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"math"
@@ -39,6 +40,7 @@ type Elasticsearch struct {
 	HealthCheckInterval config.Duration        `toml:"health_check_interval"`
 	HealthCheckTimeout  config.Duration        `toml:"health_check_timeout"`
 	IndexName           string                 `toml:"index_name"`
+	IndexTemplate       map[string]interface{} `toml:"template_index_settings"`
 	ManageTemplate      bool                   `toml:"manage_template"`
 	OverwriteTemplate   bool                   `toml:"overwrite_template"`
 	Username            config.Secret          `toml:"username"`
@@ -66,12 +68,7 @@ const telegrafTemplate = `
 	"index_patterns" : [ "{{.TemplatePattern}}" ],
 	{{ end }}
 	"settings": {
-		"index": {
+		"index": {{.IndexTemplate}}
-			"refresh_interval": "10s",
-			"mapping.total_fields.limit": 5000,
-			"auto_expand_replicas" : "0-1",
-			"codec" : "best_compression"
-		}
 	},
 	"mappings" : {
 		{{ if (lt .Version 7) }}
@@ -128,9 +125,18 @@ const telegrafTemplate = `
 	}
 }`
 
+const defaultTemplateIndexSettings = `
+{
+	"refresh_interval": "10s",
+	"mapping.total_fields.limit": 5000,
+	"auto_expand_replicas": "0-1",
+	"codec": "best_compression"
+}`
+
 type templatePart struct {
 	TemplatePattern string
 	Version         int
+	IndexTemplate   string
 }
 
 func (*Elasticsearch) SampleConfig() string {
@@ -369,19 +375,12 @@ func (a *Elasticsearch) manageTemplate(ctx context.Context) error {
 	}
 
 	if (a.OverwriteTemplate) || (!templateExists) || (templatePattern != "") {
-		tp := templatePart{
+		data, err := a.createNewTemplate(templatePattern)
-			TemplatePattern: templatePattern + "*",
+		if err != nil {
-			Version:         a.majorReleaseNumber,
-		}
-
-		t := template.Must(template.New("template").Parse(telegrafTemplate))
-		var tmpl bytes.Buffer
-
-		if err := t.Execute(&tmpl, tp); err != nil {
 			return err
 		}
-		_, errCreateTemplate := a.Client.IndexPutTemplate(a.TemplateName).BodyString(tmpl.String()).Do(ctx)
 
+		_, errCreateTemplate := a.Client.IndexPutTemplate(a.TemplateName).BodyString(data.String()).Do(ctx)
 		if errCreateTemplate != nil {
 			return fmt.Errorf("elasticsearch failed to create index template %s: %w", a.TemplateName, errCreateTemplate)
 		}
@@ -393,6 +392,33 @@ func (a *Elasticsearch) manageTemplate(ctx context.Context) error {
 	return nil
 }
 
+func (a *Elasticsearch) createNewTemplate(templatePattern string) (*bytes.Buffer, error) {
+	var indexTemplate string
+	if a.IndexTemplate != nil {
+		data, err := json.Marshal(&a.IndexTemplate)
+		if err != nil {
+			return nil, fmt.Errorf("elasticsearch failed to create index settings for template %s: %w", a.TemplateName, err)
+		}
+		indexTemplate = string(data)
+	} else {
+		indexTemplate = defaultTemplateIndexSettings
+	}
+
+	tp := templatePart{
+		TemplatePattern: templatePattern + "*",
+		Version:         a.majorReleaseNumber,
+		IndexTemplate:   indexTemplate,
+	}
+
+	t := template.Must(template.New("template").Parse(telegrafTemplate))
+	var tmpl bytes.Buffer
+
+	if err := t.Execute(&tmpl, tp); err != nil {
+		return nil, err
+	}
+	return &tmpl, nil
+}
+
 func (a *Elasticsearch) GetTagKeys(indexName string) (string, []string) {
 	tagKeys := []string{}
 	startTag := strings.Index(indexName, "{{")

plugins/outputs/elasticsearch/elasticsearch_test.go

@@ -2,6 +2,7 @@ package elasticsearch
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"math"
 	"net/http"
@@ -755,3 +756,51 @@ func TestAuthorizationHeaderWhenBearerTokenIsPresent(t *testing.T) {
 	err = e.Write(testutil.MockMetrics())
 	require.NoError(t, err)
 }
+
+func TestStandardIndexSettings(t *testing.T) {
+	e := &Elasticsearch{
+		TemplateName: "test",
+		IndexName:    "telegraf-%Y.%m.%d",
+		Log:          testutil.Logger{},
+	}
+	buf, err := e.createNewTemplate("test")
+	require.NoError(t, err)
+	var jsonData esTemplate
+	err = json.Unmarshal(buf.Bytes(), &jsonData)
+	require.NoError(t, err)
+	index := jsonData.Settings.Index
+	require.Equal(t, "10s", index["refresh_interval"])
+	require.Equal(t, float64(5000), index["mapping.total_fields.limit"])
+	require.Equal(t, "0-1", index["auto_expand_replicas"])
+	require.Equal(t, "best_compression", index["codec"])
+}
+
+func TestDifferentIndexSettings(t *testing.T) {
+	e := &Elasticsearch{
+		TemplateName: "test",
+		IndexName:    "telegraf-%Y.%m.%d",
+		IndexTemplate: map[string]interface{}{
+			"refresh_interval":           "20s",
+			"mapping.total_fields.limit": 1000,
+			"codec":                      "best_compression",
+		},
+		Log: testutil.Logger{},
+	}
+	buf, err := e.createNewTemplate("test")
+	require.NoError(t, err)
+	var jsonData esTemplate
+	err = json.Unmarshal(buf.Bytes(), &jsonData)
+	require.NoError(t, err)
+	index := jsonData.Settings.Index
+	require.Equal(t, "20s", index["refresh_interval"])
+	require.Equal(t, float64(1000), index["mapping.total_fields.limit"])
+	require.Equal(t, "best_compression", index["codec"])
+}
+
+type esTemplate struct {
+	Settings esSettings `json:"settings"`
+}
+
+type esSettings struct {
+	Index map[string]interface{} `json:"index"`
+}

plugins/outputs/elasticsearch/sample.conf

@@ -82,3 +82,13 @@
   # To pass custom HTTP headers please define it in a given below section
   # [outputs.elasticsearch.headers]
   #    "X-Custom-Header" = "custom-value"
+
+  ## Template Index Settings
+  ## Overrides the template settings.index section with any provided options.
+  ## Defaults provided here in the config
+  # template_index_settings = {
+  #   refresh_interval = "10s",
+  #   mapping.total_fields.limit = 5000,
+  #   auto_expand_replicas = "0-1",
+  #   codec = "best_compression"
+  # }