config: deprecate target_groups for static_configs

This change deprecates the `target_groups` option in favor
of `static_configs`. The old configuration is still accepted
but prints a warning.
Configuration loading errors if both options are set.

config/config.go

@@ -23,6 +23,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/prometheus/common/log"
 	"github.com/prometheus/common/model"
 	"gopkg.in/yaml.v2"
 )
@@ -399,7 +400,9 @@ type ScrapeConfig struct {
 	TLSConfig TLSConfig `yaml:"tls_config,omitempty"`
 
 	// List of labeled target groups for this job.
-	TargetGroups []*TargetGroup `yaml:"target_groups,omitempty"`
+	// XXX(fabxc): `target_groups` is deprecated.
+	TargetGroups  []*TargetGroup `yaml:"target_groups,omitempty"`
+	StaticConfigs []*TargetGroup `yaml:"static_configs,omitempty"`
 	// List of DNS service discovery configurations.
 	DNSSDConfigs []*DNSSDConfig `yaml:"dns_sd_configs,omitempty"`
 	// List of file service discovery configurations.
@@ -445,9 +448,17 @@ func (c *ScrapeConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	if c.BasicAuth != nil && (len(c.BearerToken) > 0 || len(c.BearerTokenFile) > 0) {
 		return fmt.Errorf("at most one of basic_auth, bearer_token & bearer_token_file must be configured")
 	}
+	// Check `target_groups` deprecation.
+	if c.TargetGroups != nil && c.StaticConfigs != nil {
+		return fmt.Errorf("'target_groups' is deprecated, configure static targets via 'static_configs' only")
+	}
+	if c.TargetGroups != nil {
+		log.Warnf("The 'target_groups' option for scrape configurations is deprecated, use 'static_configs' instead")
+		c.StaticConfigs = c.TargetGroups
+	}
 	// Check for users putting URLs in target groups.
 	if len(c.RelabelConfigs) == 0 {
-		for _, tg := range c.TargetGroups {
+		for _, tg := range c.StaticConfigs {
 			for _, t := range tg.Targets {
 				if err = CheckTargetAddress(t[model.AddressLabel]); err != nil {
 					return err

config/config_test.go

@@ -57,7 +57,7 @@ var expectedConf = &Config{
 
 			BearerTokenFile: "testdata/valid_token_file",
 
-			TargetGroups: []*TargetGroup{
+			StaticConfigs: []*TargetGroup{
 				{
 					Targets: []model.LabelSet{
 						{model.AddressLabel: "localhost:9090"},
@@ -409,8 +409,8 @@ func TestBadConfigs(t *testing.T) {
 	}
 }
 
-func TestBadTargetGroup(t *testing.T) {
-	content, err := ioutil.ReadFile("testdata/tgroup.bad.json")
+func TestBadStaticConfigs(t *testing.T) {
+	content, err := ioutil.ReadFile("testdata/static_config.bad.json")
 	if err != nil {
 		t.Fatal(err)
 	}

config/testdata/conf.good.yml

@@ -32,7 +32,7 @@ scrape_configs:
     - files:
       - bar/*.yaml
 
-  target_groups:
+  static_configs:
   - targets: ['localhost:9090', 'localhost:9191']
     labels:
       my:   label

config/testdata/url_in_targetgroup.bad.yml

@@ -1,5 +1,5 @@
 scrape_configs:
 - job_name: prometheus
-  target_groups:
+  static_configs:
   - targets:
     - http://bad

retrieval/targetmanager.go

@@ -402,8 +402,8 @@ func providersFromConfig(cfg *config.ScrapeConfig) map[string]TargetProvider {
 	for i, c := range cfg.AzureSDConfigs {
 		app("azure", i, discovery.NewAzureDiscovery(c))
 	}
-	if len(cfg.TargetGroups) > 0 {
-		app("static", 0, NewStaticProvider(cfg.TargetGroups))
+	if len(cfg.StaticConfigs) > 0 {
+		app("static", 0, NewStaticProvider(cfg.StaticConfigs))
 	}
 
 	return providers