Allow Azure Workload identity authentication

apis/v1alpha1/types.go

@@ -51,12 +51,14 @@ const (
 	IdentityTypeGoogleApplicationCredentials = "GoogleApplicationCredentials"
 
 	IdentityTypeAzureServicePrincipalCredentials = "AzureServicePrincipalCredentials"
+
+	IdentityTypeAzureWorkloadIdentityCredentials = "AzureWorkloadIdentityCredentials"
 )
 
 // Identity used to authenticate.
 type Identity struct {
 	// Type of identity.
-	// +kubebuilder:validation:Enum=GoogleApplicationCredentials;AzureServicePrincipalCredentials
+	// +kubebuilder:validation:Enum=GoogleApplicationCredentials;AzureServicePrincipalCredentials;AzureWorkloadIdentityCredentials
 	Type IdentityType `json:"type"`
 
 	ProviderCredentials `json:",inline"`

examples/provider/provider-config-with-secret-azure-workload-identity.yaml

@@ -0,0 +1,34 @@
+apiVersion: kubernetes.crossplane.io/v1alpha1
+kind: ProviderConfig
+metadata:
+  name: kubernetes-provider
+spec:
+  credentials:
+    source: Secret
+    secretRef:
+      namespace: crossplane-system
+      name: cluster-config
+      key: kubeconfig
+  identity:
+    type: AzureWorkloadIdentityCredentials
+    source: Secret
+    secretRef:
+      name: azure-credentials
+      namespace: crossplane-system
+      key: credentials.json
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: azure-credentials
+  namespace: crossplane-system
+stringData:
+  # serverId hardcoded to AKS ID, see https://azure.github.io/kubelogin/concepts/aks.html#azure-kubernetes-service-aad-server
+  credentials.json: |
+    {
+      "tenantId": "<aad-tenant-id>",
+      "serverId": "6dae42f8-4368-4678-94ff-3960e28e3630",
+      "clientId": "<client-id>",
+      "federatedTokenFile": "/var/run/secrets/azure/tokens/azure-identity-token",
+      "authorityHost": "https://login.microsoftonline.com/"
+     }

internal/clients/azure/azure.go

@@ -9,20 +9,25 @@ import (
 	"github.com/pkg/errors"
 	"github.com/spf13/pflag"
 	"k8s.io/client-go/rest"
+
+	apisv1alpha1 "github.com/crossplane-contrib/provider-kubernetes/apis/v1alpha1"
 )
 
 // Credentials Secret content is a json whose keys are below.
 const (
-	CredentialsKeyClientID       = "clientId"
-	CredentialsKeyClientSecret   = "clientSecret"
-	CredentialsKeyTenantID       = "tenantId"
-	CredentialsKeyClientCert     = "clientCertificate"
-	CredentialsKeyClientCertPass = "clientCertificatePassword"
+	CredentialsKeyClientID           = "clientId"
+	CredentialsKeyClientSecret       = "clientSecret"
+	CredentialsKeyTenantID           = "tenantId"
+	CredentialsKeyClientCert         = "clientCertificate"
+	CredentialsKeyClientCertPass     = "clientCertificatePassword"
+	CredentialsKeyFederatedTokenFile = "federatedTokenFile"
+	CredentialsKeyAuthorityHost      = "authorityHost"
+	CredentialsKeyServerID           = "serverId"
 )
 
 // WrapRESTConfig configures the supplied REST config to use OAuth2 bearer
 // tokens fetched using the supplied Azure Credentials.
-func WrapRESTConfig(_ context.Context, rc *rest.Config, credentials []byte, _ ...string) error {
+func WrapRESTConfig(_ context.Context, rc *rest.Config, credentials []byte, identityType apisv1alpha1.IdentityType, _ ...string) error { // nolint:gocyclo // todo: refactor
 	m := map[string]string{}
 	if err := json.Unmarshal(credentials, &m); err != nil {
 		return err
@@ -44,21 +49,30 @@ func WrapRESTConfig(_ context.Context, rc *rest.Config, credentials []byte, _ ..
 		return errors.Wrap(err, "could not parse execProvider arguments in kubeconfig")
 	}
 	rc.ExecProvider = nil
-	// TODO: support other login methods like MSI, Workload Identity in the future
-	opts.LoginMethod = token.ServicePrincipalLogin
-	opts.ClientID = m[CredentialsKeyClientID]
-	opts.ClientSecret = m[CredentialsKeyClientSecret]
-	opts.TenantID = m[CredentialsKeyTenantID]
-	if cert, ok := m[CredentialsKeyClientCert]; ok {
-		opts.ClientCert = cert
-		if certpass, ok2 := m[CredentialsKeyClientCertPass]; ok2 {
-			opts.ClientCertPassword = certpass
+	switch identityType {
+	case apisv1alpha1.IdentityTypeAzureServicePrincipalCredentials:
+		opts.LoginMethod = token.ServicePrincipalLogin
+		opts.ClientID = m[CredentialsKeyClientID]
+		opts.ClientSecret = m[CredentialsKeyClientSecret]
+		opts.TenantID = m[CredentialsKeyTenantID]
+		if cert, ok := m[CredentialsKeyClientCert]; ok {
+			opts.ClientCert = cert
+			if certpass, ok2 := m[CredentialsKeyClientCertPass]; ok2 {
+				opts.ClientCertPassword = certpass
+			}
 		}
+	case apisv1alpha1.IdentityTypeAzureWorkloadIdentityCredentials:
+		opts.LoginMethod = token.WorkloadIdentityLogin
+		opts.ClientID = m[CredentialsKeyClientID]
+		opts.TenantID = m[CredentialsKeyTenantID]
+		opts.ServerID = m[CredentialsKeyServerID]
+		opts.FederatedTokenFile = m[CredentialsKeyFederatedTokenFile]
+		opts.AuthorityHost = m[CredentialsKeyAuthorityHost]
 	}
 
 	p, err := token.NewTokenProvider(&opts)
 	if err != nil {
-		return errors.New("cannot build azure token provider")
+		return errors.Wrap(err, "cannot build azure token provider")
 	}
 
 	rc.Wrap(func(rt http.RoundTripper) http.RoundTripper {

internal/clients/kube/kube.go

@@ -105,7 +105,7 @@ func configForProvider(ctx context.Context, local client.Client, providerConfigN
 					return nil, errors.Wrap(err, errInjectGoogleCredentials)
 				}
 			}
-		case v1alpha1.IdentityTypeAzureServicePrincipalCredentials:
+		case v1alpha1.IdentityTypeAzureServicePrincipalCredentials, v1alpha1.IdentityTypeAzureWorkloadIdentityCredentials:
 			switch id.Source { //nolint:exhaustive
 			case xpv1.CredentialsSourceInjectedIdentity:
 				return nil, errors.Errorf("%s is not supported as identity source for identity type %s",
@@ -116,7 +116,7 @@ func configForProvider(ctx context.Context, local client.Client, providerConfigN
 					return nil, errors.Wrap(err, errExtractAzureCredentials)
 				}
 
-				if err := azure.WrapRESTConfig(ctx, rc, creds); err != nil {
+				if err := azure.WrapRESTConfig(ctx, rc, creds, id.Type); err != nil {
 					return nil, errors.Wrap(err, errInjectAzureCredentials)
 				}
 			}

package/crds/kubernetes.crossplane.io_providerconfigs.yaml

@@ -170,6 +170,7 @@ spec:
                     enum:
                     - GoogleApplicationCredentials
                     - AzureServicePrincipalCredentials
+                    - AzureWorkloadIdentityCredentials
                     type: string
                 required:
                 - source