lease

This example shows how to perform various lease operations on a container. The same lease operations can be performed on individual blobs as well. A lease on a container prevents it from being deleted by others, while a lease on a blob protects it from both modifications and deletions.

//go:build go1.18
// +build go1.18

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.

package main

import (
	"context"
	"fmt"
	"log"
	"os"

	"github.com/Azure/azure-sdk-for-go/sdk/azcore/to"
	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/container"
	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/lease"
)

func handleError(err error) {
	if err != nil {
		log.Fatal(err.Error())
	}
}

// This example shows how to perform various lease operations on a container.
// The same lease operations can be performed on individual blobs as well.
// A lease on a container prevents it from being deleted by others, while a lease on a blob
// protects it from both modifications and deletions.
func main() {
	// From the Azure portal, get your Storage account's name and account key.
	accountName, accountKey := os.Getenv("AZURE_STORAGE_ACCOUNT_NAME"), os.Getenv("AZURE_STORAGE_ACCOUNT_KEY")

	// Use your Storage account's name and key to create a credential object; this is used to access your account.
	credential, err := azblob.NewSharedKeyCredential(accountName, accountKey)
	handleError(err)

	// Create an containerClient object that wraps the container's URL and a default pipeline.
	containerURL := fmt.Sprintf("https://%s.blob.core.windows.net/mycontainer", accountName)
	containerClient, err := container.NewClientWithSharedKeyCredential(containerURL, credential, nil)
	handleError(err)

	// Create a unique ID for the lease
	// A lease ID can be any valid GUID string format. To generate UUIDs, consider the github.com/google/uuid package
	leaseID := "36b1a876-cf98-4eb2-a5c3-6d68489658ff"
	containerLeaseClient, err := lease.NewContainerClient(containerClient,
		&lease.ContainerClientOptions{LeaseID: to.Ptr(leaseID)})
	handleError(err)

	// Now acquire a lease on the container.
	// You can choose to pass an empty string for proposed ID so that the service automatically assigns one for you.
	duration := int32(60)
	acquireLeaseResponse, err := containerLeaseClient.AcquireLease(context.TODO(),
		&lease.ContainerAcquireOptions{Duration: &duration})
	handleError(err)
	fmt.Println("The container is leased for delete operations with lease ID", *acquireLeaseResponse.LeaseID)

	// The container cannot be deleted without providing the lease ID.
	_, err = containerClient.Delete(context.TODO(), nil)
	if err == nil {
		log.Fatal("delete should have failed")
	}

	fmt.Println("The container cannot be deleted while there is an active lease")

	// _, err = containerClient.Delete(context.TODO(), &container.DeleteOptions{
	// 	AccessConditions: &container.AccessConditions{
	// 		LeaseAccessConditions: &container.LeaseAccessConditions{LeaseID: acquireLeaseResponse.LeaseID},
	// 	},
	// })

	// We can release the lease now and the container can be deleted.
	_, err = containerLeaseClient.ReleaseLease(context.TODO(), nil)
	handleError(err)
	fmt.Println("The lease on the container is now released")

	// AcquireLease a lease again to perform other operations.
	// Duration is still 60
	acquireLeaseResponse, err = containerLeaseClient.AcquireLease(context.TODO(),
		&lease.ContainerAcquireOptions{Duration: &duration})
	handleError(err)
	fmt.Println("The container is leased again with lease ID", *acquireLeaseResponse.LeaseID)

	// We can change the ID of an existing lease.
	newLeaseID := "6b3e65e5-e1bb-4a3f-8b72-13e9bc9cd3bf"
	changeLeaseResponse, err := containerLeaseClient.ChangeLease(context.TODO(),
		&lease.ContainerChangeOptions{ProposedLeaseID: to.Ptr(newLeaseID)})
	handleError(err)
	fmt.Println("The lease ID was changed to", *changeLeaseResponse.LeaseID)

	// The lease can be renewed.
	renewLeaseResponse, err := containerLeaseClient.RenewLease(context.TODO(), nil)
	handleError(err)
	fmt.Println("The lease was renewed with the same ID", *renewLeaseResponse.LeaseID)

	// Finally, the lease can be broken, and we could prevent others from acquiring a lease for a period of time
	_, err = containerLeaseClient.BreakLease(context.TODO(), &lease.ContainerBreakOptions{BreakPeriod: to.Ptr(int32(60))})
	handleError(err)
	fmt.Println("The lease was broken, and nobody can acquire a lease for 60 seconds")
}