Azure Backend: support OIDC authentication

internal/backend/remote-state/azure/arm_client.go

@@ -81,11 +81,16 @@ func buildArmClient(ctx context.Context, config BackendConfig) (*ArmClient, erro
 		// Managed Service Identity
 		MsiEndpoint: config.MsiEndpoint,
 
+		// OIDC
+		IDTokenRequestURL:   config.OIDCRequestURL,
+		IDTokenRequestToken: config.OIDCRequestToken,
+
 		// Feature Toggles
 		SupportsAzureCliToken:          true,
 		SupportsClientCertAuth:         true,
 		SupportsClientSecretAuth:       true,
 		SupportsManagedServiceIdentity: config.UseMsi,
+		SupportsOIDCAuth:               config.UseOIDC,
 		UseMicrosoftGraph:              config.UseMicrosoftGraph,
 	}
 	armConfig, err := builder.Build()
@@ -106,13 +111,13 @@ func buildArmClient(ctx context.Context, config BackendConfig) (*ArmClient, erro
 	sender := sender.BuildSender("backend/remote-state/azure")
 	var auth autorest.Authorizer
 	if builder.UseMicrosoftGraph {
-		log.Printf("[DEBUG] Obtaining a MSAL / Microsoft Graph token for Resource Manager..")
+		log.Printf("[DEBUG] Obtaining an MSAL / Microsoft Graph token for Resource Manager..")
 		auth, err = armConfig.GetMSALToken(ctx, hamiltonEnv.ResourceManager, sender, oauthConfig, env.TokenAudience)
 		if err != nil {
 			return nil, err
 		}
 	} else {
-		log.Printf("[DEBUG] Obtaining a ADAL / Azure Active Directory Graph token for Resource Manager..")
+		log.Printf("[DEBUG] Obtaining an ADAL / Azure Active Directory Graph token for Resource Manager..")
 		auth, err = armConfig.GetADALToken(ctx, sender, oauthConfig, env.TokenAudience)
 		if err != nil {
 			return nil, err
@@ -121,14 +126,14 @@ func buildArmClient(ctx context.Context, config BackendConfig) (*ArmClient, erro
 
 	if config.UseAzureADAuthentication {
 		if builder.UseMicrosoftGraph {
-			log.Printf("[DEBUG] Obtaining a MSAL / Microsoft Graph token for Storage..")
+			log.Printf("[DEBUG] Obtaining an MSAL / Microsoft Graph token for Storage..")
 			storageAuth, err := armConfig.GetMSALToken(ctx, hamiltonEnv.Storage, sender, oauthConfig, env.ResourceIdentifiers.Storage)
 			if err != nil {
 				return nil, err
 			}
 			client.azureAdStorageAuth = &storageAuth
 		} else {
-			log.Printf("[DEBUG] Obtaining a ADAL / Azure Active Directory Graph token for Storage..")
+			log.Printf("[DEBUG] Obtaining an ADAL / Azure Active Directory Graph token for Storage..")
 			storageAuth, err := armConfig.GetADALToken(ctx, sender, oauthConfig, env.ResourceIdentifiers.Storage)
 			if err != nil {
 				return nil, err

internal/backend/remote-state/azure/backend.go

@@ -135,6 +135,28 @@ func New() backend.Backend {
 				DefaultFunc: schema.EnvDefaultFunc("ARM_MSI_ENDPOINT", ""),
 			},
 
+			// OIDC auth specific fields
+			"use_oidc": {
+				Type:        schema.TypeBool,
+				Optional:    true,
+				DefaultFunc: schema.EnvDefaultFunc("ARM_USE_OIDC", false),
+				Description: "Allow OIDC to be used for authentication",
+			},
+
+			"oidc_request_url": {
+				Type:        schema.TypeString,
+				Optional:    true,
+				DefaultFunc: schema.MultiEnvDefaultFunc([]string{"ARM_OIDC_REQUEST_URL", "ACTIONS_ID_TOKEN_REQUEST_URL"}, ""),
+				Description: "The URL for the OIDC provider from which to request an ID token",
+			},
+
+			"oidc_request_token": {
+				Type:        schema.TypeString,
+				Optional:    true,
+				DefaultFunc: schema.MultiEnvDefaultFunc([]string{"ARM_OIDC_REQUEST_TOKEN", "ACTIONS_ID_TOKEN_REQUEST_TOKEN"}, ""),
+				Description: "The bearer token for the request to the OIDC provider",
+			},
+
 			// Feature Flags
 			"use_azuread_auth": {
 				Type:        schema.TypeBool,
@@ -182,11 +204,14 @@ type BackendConfig struct {
 	MetadataHost                  string
 	Environment                   string
 	MsiEndpoint                   string
+	OIDCRequestURL                string
+	OIDCRequestToken              string
 	ResourceGroupName             string
 	SasToken                      string
 	SubscriptionID                string
 	TenantID                      string
 	UseMsi                        bool
+	UseOIDC                       bool
 	UseAzureADAuthentication      bool
 	UseMicrosoftGraph             bool
 }
@@ -213,12 +238,15 @@ func (b *Backend) configure(ctx context.Context) error {
 		MetadataHost:                  data.Get("metadata_host").(string),
 		Environment:                   data.Get("environment").(string),
 		MsiEndpoint:                   data.Get("msi_endpoint").(string),
+		OIDCRequestURL:                data.Get("oidc_request_url").(string),
+		OIDCRequestToken:              data.Get("oidc_request_token").(string),
 		ResourceGroupName:             data.Get("resource_group_name").(string),
 		SasToken:                      data.Get("sas_token").(string),
 		StorageAccountName:            data.Get("storage_account_name").(string),
 		SubscriptionID:                data.Get("subscription_id").(string),
 		TenantID:                      data.Get("tenant_id").(string),
 		UseMsi:                        data.Get("use_msi").(bool),
+		UseOIDC:                       data.Get("use_oidc").(bool),
 		UseAzureADAuthentication:      data.Get("use_azuread_auth").(bool),
 		UseMicrosoftGraph:             data.Get("use_microsoft_graph").(bool),
 	}

internal/backend/remote-state/azure/backend_test.go

@@ -39,7 +39,7 @@ func TestBackendConfig(t *testing.T) {
 	}
 }
 
-func TestBackendAccessKeyBasic(t *testing.T) {
+func TestAccBackendAccessKeyBasic(t *testing.T) {
 	testAccAzureBackend(t)
 	rs := acctest.RandString(4)
 	res := testResourceNames(rs, "testState")
@@ -65,7 +65,7 @@ func TestBackendAccessKeyBasic(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendSASTokenBasic(t *testing.T) {
+func TestAccBackendSASTokenBasic(t *testing.T) {
 	testAccAzureBackend(t)
 	rs := acctest.RandString(4)
 	res := testResourceNames(rs, "testState")
@@ -95,7 +95,35 @@ func TestBackendSASTokenBasic(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendADALAzureADAuthBasic(t *testing.T) {
+func TestAccBackendOIDCBasic(t *testing.T) {
+	testAccAzureBackend(t)
+	rs := acctest.RandString(4)
+	res := testResourceNames(rs, "testState")
+	armClient := buildTestClient(t, res)
+
+	ctx := context.TODO()
+	err := armClient.buildTestResources(ctx, &res)
+	defer armClient.destroyTestResources(ctx, res)
+	if err != nil {
+		t.Fatalf("Error creating Test Resources: %q", err)
+	}
+
+	b := backend.TestBackendConfig(t, New(), backend.TestWrapConfig(map[string]interface{}{
+		"storage_account_name": res.storageAccountName,
+		"container_name":       res.storageContainerName,
+		"key":                  res.storageKeyName,
+		"resource_group_name":  res.resourceGroup,
+		"use_oidc":             true,
+		"subscription_id":      os.Getenv("ARM_SUBSCRIPTION_ID"),
+		"tenant_id":            os.Getenv("ARM_TENANT_ID"),
+		"environment":          os.Getenv("ARM_ENVIRONMENT"),
+		"endpoint":             os.Getenv("ARM_ENDPOINT"),
+	})).(*Backend)
+
+	backend.TestBackendStates(t, b)
+}
+
+func TestAccBackendADALAzureADAuthBasic(t *testing.T) {
 	testAccAzureBackend(t)
 	rs := acctest.RandString(4)
 	res := testResourceNames(rs, "testState")
@@ -123,7 +151,7 @@ func TestBackendADALAzureADAuthBasic(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendADALManagedServiceIdentityBasic(t *testing.T) {
+func TestAccBackendADALManagedServiceIdentityBasic(t *testing.T) {
 	testAccAzureBackendRunningInAzure(t)
 	rs := acctest.RandString(4)
 	res := testResourceNames(rs, "testState")
@@ -151,7 +179,7 @@ func TestBackendADALManagedServiceIdentityBasic(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendADALServicePrincipalClientCertificateBasic(t *testing.T) {
+func TestAccBackendADALServicePrincipalClientCertificateBasic(t *testing.T) {
 	testAccAzureBackend(t)
 
 	clientCertPassword := os.Getenv("ARM_CLIENT_CERTIFICATE_PASSWORD")
@@ -188,7 +216,7 @@ func TestBackendADALServicePrincipalClientCertificateBasic(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendADALServicePrincipalClientSecretBasic(t *testing.T) {
+func TestAccBackendADALServicePrincipalClientSecretBasic(t *testing.T) {
 	testAccAzureBackend(t)
 	rs := acctest.RandString(4)
 	res := testResourceNames(rs, "testState")
@@ -217,7 +245,7 @@ func TestBackendADALServicePrincipalClientSecretBasic(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendADALServicePrincipalClientSecretCustomEndpoint(t *testing.T) {
+func TestAccBackendADALServicePrincipalClientSecretCustomEndpoint(t *testing.T) {
 	testAccAzureBackend(t)
 
 	// this is only applicable for Azure Stack.
@@ -253,7 +281,7 @@ func TestBackendADALServicePrincipalClientSecretCustomEndpoint(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendMSALAzureADAuthBasic(t *testing.T) {
+func TestAccBackendMSALAzureADAuthBasic(t *testing.T) {
 	testAccAzureBackend(t)
 	rs := acctest.RandString(4)
 	res := testResourceNames(rs, "testState")
@@ -282,7 +310,7 @@ func TestBackendMSALAzureADAuthBasic(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendMSALManagedServiceIdentityBasic(t *testing.T) {
+func TestAccBackendMSALManagedServiceIdentityBasic(t *testing.T) {
 	testAccAzureBackendRunningInAzure(t)
 	rs := acctest.RandString(4)
 	res := testResourceNames(rs, "testState")
@@ -311,7 +339,7 @@ func TestBackendMSALManagedServiceIdentityBasic(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendMSALServicePrincipalClientCertificateBasic(t *testing.T) {
+func TestAccBackendMSALServicePrincipalClientCertificateBasic(t *testing.T) {
 	testAccAzureBackend(t)
 
 	clientCertPassword := os.Getenv("ARM_CLIENT_CERTIFICATE_PASSWORD")
@@ -349,7 +377,7 @@ func TestBackendMSALServicePrincipalClientCertificateBasic(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendMSALServicePrincipalClientSecretBasic(t *testing.T) {
+func TestAccBackendMSALServicePrincipalClientSecretBasic(t *testing.T) {
 	testAccAzureBackend(t)
 	rs := acctest.RandString(4)
 	res := testResourceNames(rs, "testState")
@@ -379,7 +407,7 @@ func TestBackendMSALServicePrincipalClientSecretBasic(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendMSALServicePrincipalClientSecretCustomEndpoint(t *testing.T) {
+func TestAccBackendMSALServicePrincipalClientSecretCustomEndpoint(t *testing.T) {
 	testAccAzureBackend(t)
 
 	// this is only applicable for Azure Stack.
@@ -416,7 +444,7 @@ func TestBackendMSALServicePrincipalClientSecretCustomEndpoint(t *testing.T) {
 	backend.TestBackendStates(t, b)
 }
 
-func TestBackendAccessKeyLocked(t *testing.T) {
+func TestAccBackendAccessKeyLocked(t *testing.T) {
 	testAccAzureBackend(t)
 	rs := acctest.RandString(4)
 	res := testResourceNames(rs, "testState")
@@ -454,7 +482,7 @@ func TestBackendAccessKeyLocked(t *testing.T) {
 	backend.TestBackendStateForceUnlockInWS(t, b1, b2, "foo")
 }
 
-func TestBackendServicePrincipalLocked(t *testing.T) {
+func TestAccBackendServicePrincipalLocked(t *testing.T) {
 	testAccAzureBackend(t)
 	rs := acctest.RandString(4)
 	res := testResourceNames(rs, "testState")

internal/backend/remote-state/azure/helpers_test.go

@@ -39,6 +39,15 @@ func testAccAzureBackendRunningInAzure(t *testing.T) {
 	}
 }
 
+// these kind of tests can only run when within GitHub Actions (e.g. OIDC)
+func testAccAzureBackendRunningInGitHubActions(t *testing.T) {
+	testAccAzureBackend(t)
+
+	if os.Getenv("TF_RUNNING_IN_GITHUB_ACTIONS") == "" {
+		t.Skip("Skipping test since not running in GitHub Actions")
+	}
+}
+
 func buildTestClient(t *testing.T, res resourceNames) *ArmClient {
 	subscriptionID := os.Getenv("ARM_SUBSCRIPTION_ID")
 	tenantID := os.Getenv("ARM_TENANT_ID")

website/docs/language/settings/backends/azurerm.mdx

@@ -46,6 +46,24 @@ terraform {
 
 ***
 
+When authenticating using OpenID Connect (OIDC):
+
+```hcl
+terraform {
+  backend "azurerm" {
+    resource_group_name  = "StorageAccount-ResourceGroup"
+    storage_account_name = "abcd1234"
+    container_name       = "tfstate"
+    key                  = "prod.terraform.tfstate"
+    use_oidc             = true
+    subscription_id      = "00000000-0000-0000-0000-000000000000"
+    tenant_id            = "00000000-0000-0000-0000-000000000000"
+  }
+}
+```
+
+***
+
 When authenticating using Azure AD Authentication:
 
 ```hcl
@@ -137,6 +155,25 @@ data "terraform_remote_state" "foo" {
 
 ***
 
+When authenticating using OpenID Connect (OIDC):
+
+```hcl
+data "terraform_remote_state" "foo" {
+  backend = "azurerm"
+  config = {
+    resource_group_name  = "StorageAccount-ResourceGroup"
+    storage_account_name = "terraform123abc"
+    container_name       = "terraform-state"
+    key                  = "prod.terraform.tfstate"
+    use_oidc             = true
+    subscription_id      = "00000000-0000-0000-0000-000000000000"
+    tenant_id            = "00000000-0000-0000-0000-000000000000"
+  }
+}
+```
+
+***
+
 When authenticating using AzureAD Authentication:
 
 ```hcl
@@ -231,6 +268,18 @@ When authenticating using the Managed Service Identity (MSI) - the following fie
 
 ***
 
+When authenticating using a Service Principal with OpenID Connect (OIDC) - the following fields are also supported:
+
+* `oidc_request_url` - (Optional) The URL for the OIDC provider from which to request an ID token. This can also be sourced from the `ARM_OIDC_REQUEST_URL` or `ACTIONS_ID_TOKEN_REQUEST_URL` environment variables.
+
+* `oidc_request_token` - (Optional) The bearer token for the request to the OIDC provider. This can also be sourced from the `ARM_OIDC_REQUEST_TOKEN` or `ACTIONS_ID_TOKEN_REQUEST_TOKEN` environment variables.
+
+* `use_oidc` - (Optional) Should OIDC authentication be used? This can also be sourced from the `ARM_USE_OIDC` environment variable.
+
+~> **Note:** When using OIDC for authentication, `use_microsoft_graph` must be set to `true` (which is the default).
+
+***
+
 When authenticating using a SAS Token associated with the Storage Account - the following fields are also supported:
 
 * `sas_token` - (Optional) The SAS Token used to access the Blob Storage Account. This can also be sourced from the `ARM_SAS_TOKEN` environment variable.