{discovery,remote_write}/azure: Support default SDK authentication (#13099)

* discovery/azure: Offer default SDK authentication

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

config/config_test.go

@@ -1840,7 +1840,7 @@ var expectedErrors = []struct {
 	},
 	{
 		filename: "azure_authentication_method.bad.yml",
-		errMsg:   "unknown authentication_type \"invalid\". Supported types are \"OAuth\" or \"ManagedIdentity\"",
+		errMsg:   "unknown authentication_type \"invalid\". Supported types are \"OAuth\", \"ManagedIdentity\" or \"SDK\"",
 	},
 	{
 		filename: "azure_bearertoken_basicauth.bad.yml",

discovery/azure/azure.go

@@ -65,6 +65,7 @@ const (
 	azureLabelMachineSize          = azureLabel + "machine_size"
 
 	authMethodOAuth           = "OAuth"
+	authMethodSDK             = "SDK"
 	authMethodManagedIdentity = "ManagedIdentity"
 )
 
@@ -164,8 +165,8 @@ func (c *SDConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 		}
 	}
 
-	if c.AuthenticationMethod != authMethodOAuth && c.AuthenticationMethod != authMethodManagedIdentity {
+	if c.AuthenticationMethod != authMethodOAuth && c.AuthenticationMethod != authMethodManagedIdentity && c.AuthenticationMethod != authMethodSDK {
-		return fmt.Errorf("unknown authentication_type %q. Supported types are %q or %q", c.AuthenticationMethod, authMethodOAuth, authMethodManagedIdentity)
+		return fmt.Errorf("unknown authentication_type %q. Supported types are %q, %q or %q", c.AuthenticationMethod, authMethodOAuth, authMethodManagedIdentity, authMethodSDK)
 	}
 
 	return c.HTTPClientConfig.Validate()
@@ -294,6 +295,16 @@ func newCredential(cfg SDConfig, policyClientOptions policy.ClientOptions) (azco
 			return nil, err
 		}
 		credential = azcore.TokenCredential(secretCredential)
+	case authMethodSDK:
+		options := &azidentity.DefaultAzureCredentialOptions{ClientOptions: policyClientOptions}
+		if len(cfg.TenantID) != 0 {
+			options.TenantID = cfg.TenantID
+		}
+		sdkCredential, err := azidentity.NewDefaultAzureCredential(options)
+		if err != nil {
+			return nil, err
+		}
+		credential = azcore.TokenCredential(sdkCredential)
 	}
 	return credential, nil
 }

docs/configuration/configuration.md

@@ -600,8 +600,10 @@ See below for the configuration options for Azure discovery:
 # The Azure environment.
 [ environment: <string> | default = AzurePublicCloud ]
 
-# The authentication method, either OAuth or ManagedIdentity.
+# The authentication method, either OAuth, ManagedIdentity or SDK.
 # See https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/overview
+# SDK authentication method uses environment variables by default.
+# See https://learn.microsoft.com/en-us/azure/developer/go/azure-sdk-authentication
 [ authentication_method: <string> | default = OAuth]
 # The subscription ID. Always required.
 subscription_id: <string>
@@ -3619,6 +3621,11 @@ azuread:
       [ client_secret: <string> ]
       [ tenant_id: <string> ] ]
 
+  # Azure SDK auth.
+  # See https://learn.microsoft.com/en-us/azure/developer/go/azure-sdk-authentication
+  [ sdk:
+      [ tenant_id: <string> ] ]
+
 # Configures the remote write request's TLS settings.
 tls_config:
   [ <tls_config> ]

storage/remote/azuread/azuread.go

@@ -61,6 +61,12 @@ type OAuthConfig struct {
 	TenantID string `yaml:"tenant_id,omitempty"`
 }
 
+// SDKConfig is used to store azure SDK config values.
+type SDKConfig struct {
+	// TenantID is the tenantId of the azure active directory application that is being used to authenticate.
+	TenantID string `yaml:"tenant_id,omitempty"`
+}
+
 // AzureADConfig is used to store the config values.
 type AzureADConfig struct { //nolint:revive // exported.
 	// ManagedIdentity is the managed identity that is being used to authenticate.
@@ -69,6 +75,9 @@ type AzureADConfig struct { //nolint:revive // exported.
 	// OAuth is the oauth config that is being used to authenticate.
 	OAuth *OAuthConfig `yaml:"oauth,omitempty"`
 
+	// OAuth is the oauth config that is being used to authenticate.
+	SDK *SDKConfig `yaml:"sdk,omitempty"`
+
 	// Cloud is the Azure cloud in which the service is running. Example: AzurePublic/AzureGovernment/AzureChina.
 	Cloud string `yaml:"cloud,omitempty"`
 }
@@ -102,14 +111,22 @@ func (c *AzureADConfig) Validate() error {
 		return fmt.Errorf("must provide a cloud in the Azure AD config")
 	}
 
-	if c.ManagedIdentity == nil && c.OAuth == nil {
+	if c.ManagedIdentity == nil && c.OAuth == nil && c.SDK == nil {
-		return fmt.Errorf("must provide an Azure Managed Identity or Azure OAuth in the Azure AD config")
+		return fmt.Errorf("must provide an Azure Managed Identity, Azure OAuth or Azure SDK in the Azure AD config")
 	}
 
 	if c.ManagedIdentity != nil && c.OAuth != nil {
 		return fmt.Errorf("cannot provide both Azure Managed Identity and Azure OAuth in the Azure AD config")
 	}
 
+	if c.ManagedIdentity != nil && c.SDK != nil {
+		return fmt.Errorf("cannot provide both Azure Managed Identity and Azure SDK in the Azure AD config")
+	}
+
+	if c.OAuth != nil && c.SDK != nil {
+		return fmt.Errorf("cannot provide both Azure OAuth and Azure SDK in the Azure AD config")
+	}
+
 	if c.ManagedIdentity != nil {
 		if c.ManagedIdentity.ClientID == "" {
 			return fmt.Errorf("must provide an Azure Managed Identity client_id in the Azure AD config")
@@ -143,6 +160,17 @@ func (c *AzureADConfig) Validate() error {
 		}
 	}
 
+	if c.SDK != nil {
+		var err error
+
+		if c.SDK.TenantID != "" {
+			_, err = regexp.MatchString("^[0-9a-zA-Z-.]+$", c.SDK.TenantID)
+			if err != nil {
+				return fmt.Errorf("the provided Azure OAuth tenant_id is invalid")
+			}
+		}
+	}
+
 	return nil
 }
 
@@ -225,6 +253,16 @@ func newTokenCredential(cfg *AzureADConfig) (azcore.TokenCredential, error) {
 		}
 	}
 
+	if cfg.SDK != nil {
+		sdkConfig := &SDKConfig{
+			TenantID: cfg.SDK.TenantID,
+		}
+		cred, err = newSDKTokenCredential(clientOpts, sdkConfig)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	return cred, nil
 }
 
@@ -241,6 +279,12 @@ func newOAuthTokenCredential(clientOpts *azcore.ClientOptions, oAuthConfig *OAut
 	return azidentity.NewClientSecretCredential(oAuthConfig.TenantID, oAuthConfig.ClientID, oAuthConfig.ClientSecret, opts)
 }
 
+// newSDKTokenCredential returns new SDK token credential.
+func newSDKTokenCredential(clientOpts *azcore.ClientOptions, sdkConfig *SDKConfig) (azcore.TokenCredential, error) {
+	opts := &azidentity.DefaultAzureCredentialOptions{ClientOptions: *clientOpts, TenantID: sdkConfig.TenantID}
+	return azidentity.NewDefaultAzureCredential(opts)
+}
+
 // newTokenProvider helps to fetch accessToken for different types of credential. This also takes care of
 // refreshing the accessToken before expiry. This accessToken is attached to the Authorization header while making requests.
 func newTokenProvider(cfg *AzureADConfig, cred azcore.TokenCredential) (*tokenProvider, error) {

storage/remote/azuread/azuread_test.go

@@ -39,7 +39,7 @@ const (
 	testTokenString   = "testTokenString"
 )
 
-var testTokenExpiry = time.Now().Add(5 * time.Second)
+func testTokenExpiry() time.Time { return time.Now().Add(5 * time.Second) }
 
 type AzureAdTestSuite struct {
 	suite.Suite
@@ -94,7 +94,7 @@ func (ad *AzureAdTestSuite) TestAzureAdRoundTripper() {
 
 		testToken := &azcore.AccessToken{
 			Token:     testTokenString,
-			ExpiresOn: testTokenExpiry,
+			ExpiresOn: testTokenExpiry(),
 		}
 
 		ad.mockCredential.On("GetToken", mock.Anything, mock.Anything).Return(*testToken, nil)
@@ -145,7 +145,7 @@ func TestAzureAdConfig(t *testing.T) {
 		// Missing managedidentiy or oauth field.
 		{
 			filename: "testdata/azuread_bad_configmissing.yaml",
-			err:      "must provide an Azure Managed Identity or Azure OAuth in the Azure AD config",
+			err:      "must provide an Azure Managed Identity, Azure OAuth or Azure SDK in the Azure AD config",
 		},
 		// Invalid managedidentity client id.
 		{
@@ -162,6 +162,11 @@ func TestAzureAdConfig(t *testing.T) {
 			filename: "testdata/azuread_bad_twoconfig.yaml",
 			err:      "cannot provide both Azure Managed Identity and Azure OAuth in the Azure AD config",
 		},
+		// Invalid config when both sdk and oauth is provided.
+		{
+			filename: "testdata/azuread_bad_oauthsdkconfig.yaml",
+			err:      "cannot provide both Azure OAuth and Azure SDK in the Azure AD config",
+		},
 		// Valid config with missing  optionally cloud field.
 		{
 			filename: "testdata/azuread_good_cloudmissing.yaml",
@@ -174,6 +179,10 @@ func TestAzureAdConfig(t *testing.T) {
 		{
 			filename: "testdata/azuread_good_oauth.yaml",
 		},
+		// Valid SDK config.
+		{
+			filename: "testdata/azuread_good_sdk.yaml",
+		},
 	}
 	for _, c := range cases {
 		_, err := loadAzureAdConfig(c.filename)
@@ -232,6 +241,16 @@ func (s *TokenProviderTestSuite) TestNewTokenProvider() {
 			},
 			err: "Cloud is not specified or is incorrect: ",
 		},
+		// Invalid tokenProvider for SDK.
+		{
+			cfg: &AzureADConfig{
+				Cloud: "PublicAzure",
+				SDK: &SDKConfig{
+					TenantID: dummyTenantID,
+				},
+			},
+			err: "Cloud is not specified or is incorrect: ",
+		},
 		// Valid tokenProvider for managedidentity.
 		{
 			cfg: &AzureADConfig{
@@ -252,6 +271,15 @@ func (s *TokenProviderTestSuite) TestNewTokenProvider() {
 				},
 			},
 		},
+		// Valid tokenProvider for SDK.
+		{
+			cfg: &AzureADConfig{
+				Cloud: "AzurePublic",
+				SDK: &SDKConfig{
+					TenantID: dummyTenantID,
+				},
+			},
+		},
 	}
 	mockGetTokenCallCounter := 1
 	for _, c := range cases {
@@ -264,11 +292,11 @@ func (s *TokenProviderTestSuite) TestNewTokenProvider() {
 		} else {
 			testToken := &azcore.AccessToken{
 				Token:     testTokenString,
-				ExpiresOn: testTokenExpiry,
+				ExpiresOn: testTokenExpiry(),
 			}
 
 			s.mockCredential.On("GetToken", mock.Anything, mock.Anything).Return(*testToken, nil).Once().
-				On("GetToken", mock.Anything, mock.Anything).Return(getToken(), nil)
+				On("GetToken", mock.Anything, mock.Anything).Return(getToken(), nil).Once()
 
 			actualTokenProvider, actualErr := newTokenProvider(c.cfg, s.mockCredential)
 

storage/remote/azuread/testdata/azuread_bad_oauthsdkconfig.yaml

@@ -0,0 +1,7 @@
+cloud: AzurePublic
+oauth:
+  client_id: 00000000-0000-0000-0000-000000000000
+  client_secret: Cl1ent$ecret!
+  tenant_id: 00000000-a12b-3cd4-e56f-000000000000
+sdk:
+  tenant_id: 00000000-a12b-3cd4-e56f-000000000000

storage/remote/azuread/testdata/azuread_good_sdk.yaml

@@ -0,0 +1,3 @@
+cloud: AzurePublic
+sdk:
+  tenant_id: 00000000-a12b-3cd4-e56f-000000000000