azure_keyvault_handler.go

/*
Copyright 2022 The KEDA Authors

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package resolver

import (
	"context"
	"fmt"
	"strings"

	"github.com/Azure/azure-sdk-for-go/services/keyvault/v7.0/keyvault"
	az "github.com/Azure/go-autorest/autorest/azure"
	"github.com/Azure/go-autorest/autorest/azure/auth"
	"github.com/go-logr/logr"
	"sigs.k8s.io/controller-runtime/pkg/client"

	kedav1alpha1 "github.com/kedacore/keda/v2/apis/keda/v1alpha1"
	"github.com/kedacore/keda/v2/pkg/scalers/azure"
)

type AzureKeyVaultHandler struct {
	vault          *kedav1alpha1.AzureKeyVault
	keyvaultClient *keyvault.BaseClient
	podIdentity    kedav1alpha1.PodIdentityProvider
}

func NewAzureKeyVaultHandler(v *kedav1alpha1.AzureKeyVault, podIdentity kedav1alpha1.PodIdentityProvider) *AzureKeyVaultHandler {
	return &AzureKeyVaultHandler{
		vault:       v,
		podIdentity: podIdentity,
	}
}

func (vh *AzureKeyVaultHandler) Initialize(ctx context.Context, client client.Client, logger logr.Logger, triggerNamespace string) error {
	keyvaultResourceURL, activeDirectoryEndpoint, err := vh.getPropertiesForCloud()
	if err != nil {
		return err
	}

	authConfig, err := vh.getAuthConfig(ctx, client, logger, triggerNamespace, keyvaultResourceURL, activeDirectoryEndpoint)
	if err != nil {
		return err
	}

	authorizer, err := authConfig.Authorizer()
	if err != nil {
		return err
	}

	keyvaultClient := keyvault.New()
	keyvaultClient.Authorizer = authorizer

	vh.keyvaultClient = &keyvaultClient

	return nil
}

func (vh *AzureKeyVaultHandler) Read(ctx context.Context, secretName string, version string) (string, error) {
	result, err := vh.keyvaultClient.GetSecret(ctx, vh.vault.VaultURI, secretName, version)
	if err != nil {
		return "", err
	}

	return *result.Value, nil
}

func (vh *AzureKeyVaultHandler) getPropertiesForCloud() (string, string, error) {
	cloud := vh.vault.Cloud

	if cloud == nil {
		return az.PublicCloud.ResourceIdentifiers.KeyVault, az.PublicCloud.ActiveDirectoryEndpoint, nil
	}

	if strings.EqualFold(cloud.Type, azure.PrivateCloud) {
		if cloud.KeyVaultResourceURL == "" || cloud.ActiveDirectoryEndpoint == "" {
			err := fmt.Errorf("properties keyVaultResourceURL and activeDirectoryEndpoint must be provided for cloud %s",
				azure.PrivateCloud)
			return "", "", err
		}

		return cloud.KeyVaultResourceURL, cloud.ActiveDirectoryEndpoint, nil
	}

	env, err := az.EnvironmentFromName(cloud.Type)
	if err != nil {
		return "", "", err
	}

	return env.ResourceIdentifiers.KeyVault, env.ActiveDirectoryEndpoint, nil
}

func (vh *AzureKeyVaultHandler) getAuthConfig(ctx context.Context, client client.Client, logger logr.Logger,
	triggerNamespace, keyVaultResourceURL, activeDirectoryEndpoint string) (auth.AuthorizerConfig, error) {
	switch vh.podIdentity {
	case "", kedav1alpha1.PodIdentityProviderNone:
		clientID := vh.vault.Credentials.ClientID
		tenantID := vh.vault.Credentials.TenantID

		clientSecretName := vh.vault.Credentials.ClientSecret.ValueFrom.SecretKeyRef.Name
		clientSecretKey := vh.vault.Credentials.ClientSecret.ValueFrom.SecretKeyRef.Key
		clientSecret := resolveAuthSecret(ctx, client, logger, clientSecretName, triggerNamespace, clientSecretKey)

		if clientID == "" || tenantID == "" || clientSecret == "" {
			return nil, fmt.Errorf("clientID, tenantID and clientSecret are expected when not using a pod identity provider")
		}

		config := auth.NewClientCredentialsConfig(clientID, clientSecret, tenantID)
		config.Resource = keyVaultResourceURL
		config.AADEndpoint = activeDirectoryEndpoint

		return config, nil
	case kedav1alpha1.PodIdentityProviderAzure:
		config := auth.NewMSIConfig()
		config.Resource = keyVaultResourceURL

		return config, nil
	case kedav1alpha1.PodIdentityProviderAzureWorkload:
		return azure.NewAzureADWorkloadIdentityConfig(ctx, keyVaultResourceURL), nil
	default:
		return nil, fmt.Errorf("key vault does not support pod identity provider - %s", vh.podIdentity)
	}
}