Fail with error when autodiscover providers have no defined configs

CHANGELOG.next.asciidoc

@@ -239,6 +239,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Add aws overview dashboard. {issue}11007[11007] {pull}12175[12175]
 - Add `decompress_gzip_field` processor. {pull}12733[12733]
 - Add `timestamp` processor for parsing time fields. {pull}12699[12699]
+- Fail with error when autodiscover providers have no defined configs. {pull}13078[13078]
 - Add a check so alias creation explicitely fails if there is an index with the same name. {pull}13070[13070]
 - Update kubernetes watcher to use official client-go libraries. {pull}13051[13051]
 - Add support for unix epoch time values in the `timestamp` processor. {pull}13319[13319]

libbeat/autodiscover/providers/docker/docker.go

@@ -20,10 +20,11 @@
 package docker
 
 import (
-	"errors"
+	"fmt"
 	"time"
 
 	"github.com/gofrs/uuid"
+	"github.com/pkg/errors"
 
 	"github.com/elastic/beats/libbeat/autodiscover"
 	"github.com/elastic/beats/libbeat/autodiscover/builder"
@@ -60,37 +61,45 @@ type Provider struct {
 // AutodiscoverBuilder builds and returns an autodiscover provider
 func AutodiscoverBuilder(bus bus.Bus, uuid uuid.UUID, c *common.Config) (autodiscover.Provider, error) {
 	cfgwarn.Beta("The docker autodiscover is beta")
+
+	errWrap := func(err error) error {
+		return errors.Wrap(err, "error setting up docker autodiscover provider")
+	}
+
 	config := defaultConfig()
 	err := c.Unpack(&config)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	watcher, err := docker.NewWatcher(config.Host, config.TLS, false)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	mapper, err := template.NewConfigMapper(config.Templates)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
+	}
+	if len(mapper) == 0 && !config.Hints.Enabled() {
+		return nil, errWrap(fmt.Errorf("no configs or hints defined for autodiscover provider"))
 	}
 
 	builders, err := autodiscover.NewBuilders(config.Builders, config.Hints)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	appenders, err := autodiscover.NewAppenders(config.Appenders)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	start := watcher.ListenStart()
 	stop := watcher.ListenStop()
 
 	if err := watcher.Start(); err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	return &Provider{

libbeat/autodiscover/providers/docker/docker_integration_test.go

@@ -23,6 +23,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/elastic/beats/libbeat/autodiscover/template"
+
 	"github.com/gofrs/uuid"
 	"github.com/stretchr/testify/assert"
 
@@ -45,6 +47,9 @@ func TestDockerStart(t *testing.T) {
 	bus := bus.New("test")
 	config := defaultConfig()
 	config.CleanupTimeout = 0
+
+	s := &template.MapperSettings{nil, nil}
+	config.Templates = *s
 	provider, err := AutodiscoverBuilder(bus, UUID, common.MustNewConfigFrom(config))
 	if err != nil {
 		t.Fatal(err)

libbeat/autodiscover/providers/jolokia/jolokia.go

@@ -18,7 +18,10 @@
 package jolokia
 
 import (
+	"fmt"
+
 	"github.com/gofrs/uuid"
+	"github.com/pkg/errors"
 
 	"github.com/elastic/beats/libbeat/autodiscover"
 	"github.com/elastic/beats/libbeat/autodiscover/template"
@@ -50,10 +53,14 @@ type Provider struct {
 // AutodiscoverBuilder builds a Jolokia Discovery autodiscover provider, it fails if
 // there is some problem with the configuration
 func AutodiscoverBuilder(bus bus.Bus, uuid uuid.UUID, c *common.Config) (autodiscover.Provider, error) {
+	errWrap := func(err error) error {
+		return errors.Wrap(err, "error setting up jolokia autodiscover provider")
+	}
+
 	config := defaultConfig()
 	err := c.Unpack(&config)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	discovery := &Discovery{
@@ -63,17 +70,20 @@ func AutodiscoverBuilder(bus bus.Bus, uuid uuid.UUID, c *common.Config) (autodis
 
 	mapper, err := template.NewConfigMapper(config.Templates)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
+	}
+	if len(mapper) == 0 {
+		return nil, errWrap(fmt.Errorf("no configs defined for autodiscover provider"))
 	}
 
 	builders, err := autodiscover.NewBuilders(config.Builders, nil)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	appenders, err := autodiscover.NewAppenders(config.Appenders)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	return &Provider{

libbeat/autodiscover/providers/kubernetes/kubernetes.go

@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"github.com/gofrs/uuid"
+	"github.com/pkg/errors"
 
 	"github.com/elastic/beats/libbeat/autodiscover"
 	"github.com/elastic/beats/libbeat/autodiscover/builder"
@@ -56,20 +57,25 @@ type Provider struct {
 // AutodiscoverBuilder builds and returns an autodiscover provider
 func AutodiscoverBuilder(bus bus.Bus, uuid uuid.UUID, c *common.Config) (autodiscover.Provider, error) {
 	cfgwarn.Beta("The kubernetes autodiscover is beta")
+
+	errWrap := func(err error) error {
+		return errors.Wrap(err, "error setting up kubernetes autodiscover provider")
+	}
+
 	config := defaultConfig()
 	err := c.Unpack(&config)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	client, err := kubernetes.GetKubernetesClient(config.KubeConfig)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	metagen, err := kubernetes.NewMetaGenerator(c)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	config.Host = kubernetes.DiscoverKubernetesNode(config.Host, kubernetes.IsInCluster(config.KubeConfig), client)
@@ -80,22 +86,25 @@ func AutodiscoverBuilder(bus bus.Bus, uuid uuid.UUID, c *common.Config) (autodis
 		Namespace:   config.Namespace,
 	})
 	if err != nil {
-		return nil, fmt.Errorf("kubernetes: Couldn't create watcher for %T due to error %+v", &kubernetes.Pod{}, err)
+		return nil, errWrap(fmt.Errorf("couldn't create watcher for %T due to error %+v", &kubernetes.Pod{}, err))
 	}
 
 	mapper, err := template.NewConfigMapper(config.Templates)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
+	}
+	if len(mapper) == 0 && !config.Hints.Enabled() {
+		return nil, errWrap(fmt.Errorf("no configs or hints defined for autodiscover provider"))
 	}
 
 	builders, err := autodiscover.NewBuilders(config.Builders, config.Hints)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	appenders, err := autodiscover.NewAppenders(config.Appenders)
 	if err != nil {
-		return nil, err
+		return nil, errWrap(err)
 	}
 
 	p := &Provider{