Scaleway SD: Add the ability to read token from file

Prometheus adds the ability to read secrets from files. This add
this feature for the scaleway service discovery.

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

config/config_test.go

@@ -1136,6 +1136,18 @@ var expectedErrors = []struct {
 		filename: "eureka_invalid_server.bad.yml",
 		errMsg:   "invalid eureka server URL",
 	},
+	{
+		filename: "scaleway_role.bad.yml",
+		errMsg:   `unknown role "invalid"`,
+	},
+	{
+		filename: "scaleway_no_secret.bad.yml",
+		errMsg:   "one of secret_key & secret_key_file must be configured",
+	},
+	{
+		filename: "scaleway_two_secrets.bad.yml",
+		errMsg:   "at most one of secret_key & secret_key_file must be configured",
+	},
 }
 
 func TestBadConfigs(t *testing.T) {

config/testdata/scaleway_no_secret.bad.yml

@@ -0,0 +1,5 @@
+scrape_configs:
+- scaleway_sd_configs:
+    - role: instance
+      project_id: 11111111-1111-1111-1111-111111111112
+      access_key: SCWXXXXXXXXXXXXXXXXX

config/testdata/scaleway_role.bad.yml

@@ -1,4 +1,7 @@
 scrape_configs:
 - scaleway_sd_configs:
     - role: invalid
+      project_id: 11111111-1111-1111-1111-111111111112
+      access_key: SCWXXXXXXXXXXXXXXXXX
+      secret_key_file: bar
 

config/testdata/scaleway_two_secrets.bad.yml

@@ -0,0 +1,8 @@
+scrape_configs:
+- scaleway_sd_configs:
+    - role: instance
+      project_id: 11111111-1111-1111-1111-111111111112
+      access_key: SCWXXXXXXXXXXXXXXXXX
+      secret_key_file: bar
+      secret_key: 11111111-1111-1111-1111-111111111112
+

discovery/scaleway/baremetal.go

@@ -75,10 +75,18 @@ func newBaremetalDiscovery(conf *SDConfig) (*baremetalDiscovery, error) {
 		return nil, err
 	}
 
+	if conf.SecretKeyFile != "" {
+		rt, err = newAuthTokenFileRoundTripper(conf.SecretKeyFile, rt)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	profile, err := loadProfile(conf)
 	if err != nil {
 		return nil, err
 	}
+
 	d.client, err = scw.NewClient(
 		scw.WithHTTPClient(&http.Client{
 			Transport: rt,

discovery/scaleway/instance.go

@@ -76,7 +76,7 @@ func newInstanceDiscovery(conf *SDConfig) (*instanceDiscovery, error) {
 		zone:       conf.Zone,
 		project:    conf.Project,
 		accessKey:  conf.AccessKey,
-		secretKey:  string(conf.SecretKey),
+		secretKey:  conf.secretKeyForConfig(),
 		nameFilter: conf.NameFilter,
 		tagsFilter: conf.TagsFilter,
 	}
@@ -86,6 +86,13 @@ func newInstanceDiscovery(conf *SDConfig) (*instanceDiscovery, error) {
 		return nil, err
 	}
 
+	if conf.SecretKeyFile != "" {
+		rt, err = newAuthTokenFileRoundTripper(conf.SecretKeyFile, rt)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	profile, err := loadProfile(conf)
 	if err != nil {
 		return nil, err

discovery/scaleway/instance_test.go

@@ -28,6 +28,7 @@ import (
 
 var (
 	testProjectID     = "8feda53f-15f0-447f-badf-ebe32dad2fc0"
+	testSecretKeyFile = "testdata/secret_key"
 	testSecretKey     = "6d6579e5-a5b9-49fc-a35f-b4feb9b87301"
 	testAccessKey     = "SCW0W8NG6024YHRJ7723"
 )
@@ -137,3 +138,28 @@ func mockScalewayInstance(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 }
+
+func TestScalewayInstanceAuthToken(t *testing.T) {
+	mock := httptest.NewServer(http.HandlerFunc(mockScalewayInstance))
+	defer mock.Close()
+
+	cfgString := fmt.Sprintf(`
+---
+role: instance
+project_id: %s
+secret_key_file: %s
+access_key: %s
+api_url: %s
+`, testProjectID, testSecretKeyFile, testAccessKey, mock.URL)
+	var cfg SDConfig
+	require.NoError(t, yaml.UnmarshalStrict([]byte(cfgString), &cfg))
+
+	d, err := newRefresher(&cfg)
+	require.NoError(t, err)
+
+	ctx := context.Background()
+	tgs, err := d.refresh(ctx)
+	require.NoError(t, err)
+
+	require.Equal(t, 1, len(tgs))
+}

discovery/scaleway/scaleway.go

@@ -15,6 +15,9 @@ package scaleway
 
 import (
 	"context"
+	"io/ioutil"
+	"net/http"
+	"strings"
 	"time"
 
 	"github.com/go-kit/kit/log"
@@ -83,6 +86,8 @@ type SDConfig struct {
 	AccessKey string `yaml:"access_key"`
 	// SecretKey used to authenticate on Scaleway APIs.
 	SecretKey config.Secret `yaml:"secret_key"`
+	// SecretKey used to authenticate on Scaleway APIs.
+	SecretKeyFile string `yaml:"secret_key_file"`
 	// NameFilter to filter on during the ListServers.
 	NameFilter string `yaml:"name_filter,omitempty"`
 	// TagsFilter to filter on during the ListServers.
@@ -100,6 +105,15 @@ func (c SDConfig) Name() string {
 	return "scaleway"
 }
 
+// secretKeyForConfig returns a secret key that looks like a UUID, even if we
+// take the actuel secret from a file.
+func (c SDConfig) secretKeyForConfig() string {
+	if c.SecretKeyFile != "" {
+		return "00000000-0000-0000-0000-000000000000"
+	}
+	return string(c.SecretKey)
+}
+
 // UnmarshalYAML implements the yaml.Unmarshaler interface.
 func (c *SDConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	*c = DefaultSDConfig
@@ -117,8 +131,12 @@ func (c *SDConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 		return errors.New("project_id is mandatory")
 	}
 
-	if c.SecretKey == "" {
-		return errors.New("secret_key is mandatory")
+	if c.SecretKey == "" && c.SecretKeyFile == "" {
+		return errors.New("one of secret_key & secret_key_file must be configured")
+	}
+
+	if c.SecretKey != "" && c.SecretKeyFile != "" {
+		return errors.New("at most one of secret_key & secret_key_file must be configured")
 	}
 
 	if c.AccessKey == "" {
@@ -145,6 +163,7 @@ func (c SDConfig) NewDiscoverer(options discovery.DiscovererOptions) (discovery.
 
 // SetDirectory joins any relative file paths with dir.
 func (c *SDConfig) SetDirectory(dir string) {
+	c.SecretKeyFile = config.JoinDir(dir, c.SecretKeyFile)
 	c.HTTPClientConfig.SetDirectory(dir)
 }
 
@@ -190,7 +209,7 @@ func loadProfile(sdConfig *SDConfig) (*scw.Profile, error) {
 	prometheusConfigProfile := &scw.Profile{
 		DefaultZone:      scw.StringPtr(sdConfig.Zone),
 		APIURL:           scw.StringPtr(sdConfig.APIURL),
-		SecretKey:        scw.StringPtr(string(sdConfig.SecretKey)),
+		SecretKey:        scw.StringPtr(sdConfig.secretKeyForConfig()),
 		AccessKey:        scw.StringPtr(sdConfig.AccessKey),
 		DefaultProjectID: scw.StringPtr(sdConfig.Project),
 		SendTelemetry:    scw.BoolPtr(false),
@@ -198,3 +217,29 @@ func loadProfile(sdConfig *SDConfig) (*scw.Profile, error) {
 
 	return prometheusConfigProfile, nil
 }
+
+type authTokenFileRoundTripper struct {
+	authTokenFile string
+	rt            http.RoundTripper
+}
+
+// newAuthTokenFileRoundTripper adds the auth token read from the file to a request.
+func newAuthTokenFileRoundTripper(tokenFile string, rt http.RoundTripper) (http.RoundTripper, error) {
+	// fail-fast if we can't read the file.
+	_, err := ioutil.ReadFile(tokenFile)
+	if err != nil {
+		return nil, errors.Wrapf(err, "unable to read auth token file %s", tokenFile)
+	}
+	return &authTokenFileRoundTripper{tokenFile, rt}, nil
+}
+
+func (rt *authTokenFileRoundTripper) RoundTrip(request *http.Request) (*http.Response, error) {
+	b, err := ioutil.ReadFile(rt.authTokenFile)
+	if err != nil {
+		return nil, errors.Wrapf(err, "unable to read auth token file %s", rt.authTokenFile)
+	}
+	authToken := strings.TrimSpace(string(b))
+
+	request.Header.Set("X-Auth-Token", authToken)
+	return rt.rt.RoundTrip(request)
+}

discovery/scaleway/testdata/secret_key

@@ -0,0 +1 @@
+6d6579e5-a5b9-49fc-a35f-b4feb9b87301

docs/configuration/configuration.md

@@ -1589,7 +1589,12 @@ See below for the configuration options for Scaleway discovery:
 access_key: <string>
 
 # Secret key to use when listing targets. https://console.scaleway.com/project/credentials
-secret_key: <secret>
+# It is mutually exclusive with `secret_key_file`.
+[ secret_key: <secret> ]
+
+# Sets the secret key with the credentials read from the configured file.
+# It is mutually exclusive with `secret_key`.
+[ secret_key_file: <filename> ]
 
 # Project ID of the targets.
 project_id: <string>