Kubernetes SD authentication options cleanup

config/config.go

@@ -626,22 +626,6 @@ type MarathonSDConfig struct {
 	XXX map[string]interface{} `yaml:",inline"`
 }
 
-// KubernetesSDConfig is the configuration for Kubernetes service discovery.
-type KubernetesSDConfig struct {
-	Masters         []URL     `yaml:"masters"`
-	KubeletPort     int       `yaml:"kubelet_port,omitempty"`
-	InCluster       bool      `yaml:"in_cluster,omitempty"`
-	BearerTokenFile string    `yaml:"bearer_token_file,omitempty"`
-	Username        string    `yaml:"username,omitempty"`
-	Password        string    `yaml:"password,omitempty"`
-	RetryInterval   Duration  `yaml:"retry_interval,omitempty"`
-	RequestTimeout  Duration  `yaml:"request_timeout,omitempty"`
-	TLSConfig       TLSConfig `yaml:"tls_config,omitempty"`
-
-	// Catches all undefined fields and must be empty after parsing.
-	XXX map[string]interface{} `yaml:",inline"`
-}
-
 // UnmarshalYAML implements the yaml.Unmarshaler interface.
 func (c *MarathonSDConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	*c = DefaultMarathonSDConfig
@@ -657,6 +641,22 @@ func (c *MarathonSDConfig) UnmarshalYAML(unmarshal func(interface{}) error) erro
 	return checkOverflow(c.XXX, "marathon_sd_config")
 }
 
+// KubernetesSDConfig is the configuration for Kubernetes service discovery.
+type KubernetesSDConfig struct {
+	Masters         []URL      `yaml:"masters"`
+	KubeletPort     int        `yaml:"kubelet_port,omitempty"`
+	InCluster       bool       `yaml:"in_cluster,omitempty"`
+	BasicAuth       *BasicAuth `yaml:"basic_auth,omitempty"`
+	BearerToken     string     `yaml:"bearer_token,omitempty"`
+	BearerTokenFile string     `yaml:"bearer_token_file,omitempty"`
+	RetryInterval   Duration   `yaml:"retry_interval,omitempty"`
+	RequestTimeout  Duration   `yaml:"request_timeout,omitempty"`
+	TLSConfig       TLSConfig  `yaml:"tls_config,omitempty"`
+
+	// Catches all undefined fields and must be empty after parsing.
+	XXX map[string]interface{} `yaml:",inline"`
+}
+
 // UnmarshalYAML implements the yaml.Unmarshaler interface.
 func (c *KubernetesSDConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	*c = DefaultKubernetesSDConfig
@@ -668,6 +668,12 @@ func (c *KubernetesSDConfig) UnmarshalYAML(unmarshal func(interface{}) error) er
 	if len(c.Masters) == 0 {
 		return fmt.Errorf("Kubernetes SD configuration requires at least one Kubernetes master")
 	}
+	if len(c.BearerToken) > 0 && len(c.BearerTokenFile) > 0 {
+		return fmt.Errorf("at most one of bearer_token & bearer_token_file must be configured")
+	}
+	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")
+	}
 
 	return checkOverflow(c.XXX, "kubernetes_sd_config")
 }

config/config_test.go

@@ -203,9 +203,11 @@ var expectedConf = &Config{
 
 			KubernetesSDConfigs: []*KubernetesSDConfig{
 				{
-					Masters:        []URL{kubernetesSDHostURL()},
-					Username:       "myusername",
-					Password:       "mypassword",
+					Masters: []URL{kubernetesSDHostURL()},
+					BasicAuth: &BasicAuth{
+						Username: "myusername",
+						Password: "mypassword",
+					},
 					KubeletPort:    10255,
 					RequestTimeout: Duration(10 * time.Second),
 					RetryInterval:  Duration(1 * time.Second),
@@ -324,6 +326,12 @@ var expectedErrors = []struct {
 	}, {
 		filename: "bearertoken_basicauth.bad.yml",
 		errMsg:   "at most one of basic_auth, bearer_token & bearer_token_file must be configured",
+	}, {
+		filename: "kubernetes_bearertoken.bad.yml",
+		errMsg:   "at most one of bearer_token & bearer_token_file must be configured",
+	}, {
+		filename: "kubernetes_bearertoken_basicauth.bad.yml",
+		errMsg:   "at most one of basic_auth, bearer_token & bearer_token_file must be configured",
 	}, {
 		filename: "marathon_no_servers.bad.yml",
 		errMsg:   "Marathon SD config must contain at least one Marathon server",

config/testdata/conf.good.yml

@@ -107,8 +107,10 @@ scrape_configs:
   kubernetes_sd_configs:
   - masters:
     - 'https://localhost:1234'
-    username: 'myusername'
-    password: 'mypassword'
+
+    basic_auth:
+      username: 'myusername'
+      password: 'mypassword'
 
 - job_name: service-marathon
   marathon_sd_configs:

config/testdata/kubernetes_bearertoken.bad.yml

@@ -0,0 +1,10 @@
+scrape_configs:
+  - job_name: prometheus
+
+    kubernetes_sd_configs:
+    - masters:
+      - 'https://localhost:1234'
+
+      bearer_token: 1234
+      bearer_token_file: somefile
+

config/testdata/kubernetes_bearertoken_basicauth.bad.yml

@@ -0,0 +1,12 @@
+scrape_configs:
+  - job_name: prometheus
+
+    kubernetes_sd_configs:
+    - masters:
+      - 'https://localhost:1234'
+
+      bearer_token: 1234
+      basic_auth:
+        username: user
+        password: password
+

retrieval/discovery/kubernetes/discovery.go

@@ -624,16 +624,22 @@ func newKubernetesHTTPClient(conf *config.KubernetesSDConfig) (*http.Client, err
 		TLSClientConfig: tlsConfig,
 	}
 
-	bearerToken, err := ioutil.ReadFile(bearerTokenFile)
-	if err != nil {
-		return nil, err
+	// If a bearer token is provided, create a round tripper that will set the
+	// Authorization header correctly on each request.
+	bearerToken := conf.BearerToken
+	if len(bearerToken) == 0 && len(bearerTokenFile) > 0 {
+		b, err := ioutil.ReadFile(bearerTokenFile)
+		if err != nil {
+			return nil, fmt.Errorf("unable to read bearer token file %s: %s", bearerTokenFile, err)
+		}
+		bearerToken = string(b)
+	}
+	if len(bearerToken) > 0 {
+		rt = httputil.NewBearerAuthRoundTripper(bearerToken, rt)
 	}
 
-	if len(bearerToken) > 0 {
-		rt = httputil.NewBearerAuthRoundTripper(string(bearerToken), rt)
-	}
-	if len(conf.Username) > 0 && len(conf.Password) > 0 {
-		rt = httputil.NewBasicAuthRoundTripper(conf.Username, conf.Password, rt)
+	if conf.BasicAuth != nil {
+		rt = httputil.NewBasicAuthRoundTripper(conf.BasicAuth.Username, conf.BasicAuth.Password, rt)
 	}
 
 	return &http.Client{