outputs/postgresql: Refactor initialization to use telegraf convention

plugins/outputs/postgresql/postgresql.go

@@ -12,8 +12,6 @@ import (
 	"github.com/jackc/pgx/v4"
 	"github.com/jackc/pgx/v4/pgxpool"
 
-	"github.com/influxdata/toml"
-
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/config"
 	"github.com/influxdata/telegraf/models"
@@ -51,53 +49,51 @@ var sampleConfig = `
   ## with the same name as the user. This dbname is just for instantiating a
   ## connection with the server and doesn't restrict the databases we are trying
   ## to grab metrics for.
-  ##
-  #connection = "host=localhost user=postgres sslmode=verify-full"
 
   ## Postgres schema to use.
-  schema = "public"
+  # schema = "public"
 
   ## Store tags as foreign keys in the metrics table. Default is false.
-  tags_as_foreign_keys = false
+  # tags_as_foreign_keys = false
 
   ## Suffix to append to table name (measurement name) for the foreign tag table.
-  tag_table_suffix = "_tag"
+  # tag_table_suffix = "_tag"
 
   ## Deny inserting metrics if the foreign tag can't be inserted.
-  foreign_tag_constraint = false
+  # foreign_tag_constraint = false
 
   ## Store all tags as a JSONB object in a single 'tags' column.
-  tags_as_jsonb = false
+  # tags_as_jsonb = false
 
   ## Store all fields as a JSONB object in a single 'fields' column.
-  fields_as_jsonb = false
+  # fields_as_jsonb = false
 
   ## Templated statements to execute when creating a new table.
-  create_templates = [
-    '''CREATE TABLE {{.table}} ({{.columns}})''',
-  ]
+  # create_templates = [
+  #   '''CREATE TABLE {{.table}} ({{.columns}})''',
+  # ]
 
   ## Templated statements to execute when adding columns to a table.
   ## Set to an empty list to disable. Points containing tags for which there is no column will be skipped. Points
   ## containing fields for which there is no column will have the field omitted.
-  add_column_templates = [
-    '''ALTER TABLE {{.table}} ADD COLUMN IF NOT EXISTS {{.columns|join ", ADD COLUMN IF NOT EXISTS "}}''',
-  ]
+  # add_column_templates = [
+  #   '''ALTER TABLE {{.table}} ADD COLUMN IF NOT EXISTS {{.columns|join ", ADD COLUMN IF NOT EXISTS "}}''',
+  # ]
 
   ## Templated statements to execute when creating a new tag table.
-  tag_table_create_templates = [
-    '''CREATE TABLE {{.table}} ({{.columns}}, PRIMARY KEY (tag_id))''',
-  ]
+  # tag_table_create_templates = [
+  #   '''CREATE TABLE {{.table}} ({{.columns}}, PRIMARY KEY (tag_id))''',
+  # ]
 
   ## Templated statements to execute when adding columns to a tag table.
   ## Set to an empty list to disable. Points containing tags for which there is no column will be skipped.
-  tag_table_add_column_templates = [
-    '''ALTER TABLE {{.table}} ADD COLUMN IF NOT EXISTS {{.columns|join ", ADD COLUMN IF NOT EXISTS "}}''',
-  ]
+  # tag_table_add_column_templates = [
+  #   '''ALTER TABLE {{.table}} ADD COLUMN IF NOT EXISTS {{.columns|join ", ADD COLUMN IF NOT EXISTS "}}''',
+  # ]
 
   ## When using pool_max_conns>1, an a temporary error occurs, the query is retried with an incremental backoff. This
   ## controls the maximum backoff duration.
-  retry_max_backoff = "15s"
+  # retry_max_backoff = "15s"
 
   ## Enable & set the log level for the Postgres driver.
   # log_level = "info" # trace, debug, info, warn, error, none
@@ -135,13 +131,60 @@ func init() {
 }
 
 func newPostgresql() *Postgresql {
-	p := &Postgresql{
-		Logger: models.NewLogger("outputs", "postgresql", ""),
+	return &Postgresql{}
+}
+
+func (p *Postgresql) Init() error {
+	if p.Schema == "" {
+		p.Schema = "public"
+	}
+
+	if p.TagTableSuffix == "" {
+		p.TagTableSuffix = "_tag"
 	}
-	if err := toml.Unmarshal([]byte(p.SampleConfig()), p); err != nil {
-		panic(err.Error())
+
+	if p.CreateTemplates == nil {
+		t := &sqltemplate.Template{}
+		t.UnmarshalText([]byte(`CREATE TABLE {{.table}} ({{.columns}})`))
+		p.CreateTemplates = []*sqltemplate.Template{t}
+	}
+
+	if p.AddColumnTemplates == nil {
+		t := &sqltemplate.Template{}
+		t.UnmarshalText([]byte(`ALTER TABLE {{.table}} ADD COLUMN IF NOT EXISTS {{.columns|join ", ADD COLUMN IF NOT EXISTS "}}`))
+		p.AddColumnTemplates = []*sqltemplate.Template{t}
 	}
-	return p
+
+	if p.TagTableCreateTemplates == nil {
+		t := &sqltemplate.Template{}
+		t.UnmarshalText([]byte(`CREATE TABLE {{.table}} ({{.columns}}, PRIMARY KEY (tag_id))`))
+		p.TagTableCreateTemplates = []*sqltemplate.Template{t}
+	}
+
+	if p.TagTableAddColumnTemplates == nil {
+		t := &sqltemplate.Template{}
+		t.UnmarshalText([]byte(`ALTER TABLE {{.table}} ADD COLUMN IF NOT EXISTS {{.columns|join ", ADD COLUMN IF NOT EXISTS "}}`))
+		p.TagTableAddColumnTemplates = []*sqltemplate.Template{t}
+	}
+
+	if p.RetryMaxBackoff == 0 {
+		p.RetryMaxBackoff = config.Duration(time.Second * 15)
+	}
+
+	if p.LogLevel == "" {
+		p.LogLevel = "info"
+	}
+
+	if p.TagTableAddColumnTemplates == nil {
+		t := &sqltemplate.Template{}
+		t.UnmarshalText([]byte(`ALTER TABLE {{.table}} ADD COLUMN IF NOT EXISTS {{.columns|join ", ADD COLUMN IF NOT EXISTS "}}`))
+	}
+
+	if p.Logger == nil {
+		p.Logger = models.NewLogger("outputs", "postgresql", "")
+	}
+
+	return nil
 }
 
 func (p *Postgresql) SampleConfig() string { return sampleConfig }

plugins/outputs/postgresql/postgresql_test.go

@@ -2,14 +2,19 @@ package postgresql
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
-	"github.com/influxdata/telegraf/testutil"
 	"os"
+	"regexp"
 	"strings"
 	"sync"
 	"testing"
 	"time"
 
+	"github.com/influxdata/toml"
+
+	"github.com/influxdata/telegraf/testutil"
+
 	"github.com/jackc/pgx/v4"
 	"github.com/jackc/pgx/v4/pgxpool"
 	"github.com/stretchr/testify/assert"
@@ -211,6 +216,7 @@ type PostgresqlTest struct {
 
 func newPostgresqlTest(tb testing.TB) *PostgresqlTest {
 	p := newPostgresql()
+	p.Init()
 	logger := NewLogAccumulator(tb)
 	p.Logger = logger
 	pt := &PostgresqlTest{Postgresql: *p}
@@ -220,6 +226,26 @@ func newPostgresqlTest(tb testing.TB) *PostgresqlTest {
 	return pt
 }
 
+// Verify that the documented defaults match the actual defaults.
+//
+// Sample config must be in the format documented in `docs/developers/SAMPLE_CONFIG.md`.
+func TestPostgresqlSampleConfig(t *testing.T) {
+	p1 := newPostgresql()
+	require.NoError(t, p1.Init())
+
+	p2 := newPostgresql()
+	re := regexp.MustCompile(`(?m)^\s*#`)
+	conf := re.ReplaceAllLiteralString(p1.SampleConfig(), "")
+	require.NoError(t, toml.Unmarshal([]byte(conf), p2))
+	require.NoError(t, p2.Init())
+
+	// Can't use assert.Equal() because it dives into unexported fields that contain unequal values.
+	// Serializing to JSON is effective as any differences will be visible in exported fields.
+	p1json, _ := json.Marshal(p1)
+	p2json, _ := json.Marshal(p2)
+	assert.JSONEq(t, string(p1json), string(p2json), "Sample config does not match default config")
+}
+
 func TestPostgresqlConnect(t *testing.T) {
 	p := newPostgresqlTest(t)
 	require.NoError(t, p.Connect())

plugins/outputs/postgresql/sqltemplate/template.go

@@ -124,15 +124,6 @@ import (
 	"github.com/Masterminds/sprig"
 )
 
-// TableCreateTemplate is the default template used for creating new tables.
-var TableCreateTemplate = newTemplate(`CREATE TABLE {{.table}} ({{.columns}})`)
-
-// TagTableCreateTemplate is the default template used when creating a new tag table.
-var TagTableCreateTemplate = newTemplate(`CREATE TABLE {{.table}} ({{.columns}}, PRIMARY KEY (tag_id))`)
-
-// TableAddColumnTemplate is the default template used when adding new columns to an existing table.
-var TableAddColumnTemplate = newTemplate(`ALTER TABLE {{.table}} ADD COLUMN IF NOT EXISTS {{.columns|join ", ADD COLUMN IF NOT EXISTS "}}`)
-
 var templateFuncs = map[string]interface{}{
 	"quoteIdentifier": QuoteIdentifier,
 	"quoteLiteral":    QuoteLiteral,