GoAzureLocking

About

The package provides a simple interface to handle locking between components running in Azure. It requires an Azure Storage account and use a Lease on storage containers behind the scenes.

Using

Create a LockInstance for a lock named lock1

lock, err := goazurelocking.NewLockInstance(ctx, "https://azureStorageAccountNameHere.blob.core.windows.net",
 "azureStorageKeyHere", "lock1", time.Duration(time.Second*5))
if err != nil {
	panic(err)
}
defer lock.Unlock() // This will 'Unlock' the lock and cleanup go routines running, for example autorenew, on exit. 

Note: The storage account URL should be provided in full, including the https://. This allows for the library to be used against Azure Stack (untested). For a standards storage account this will be https://THE-ACCOUNT-NAME-HERE.blob.core.windows.net

Obtain a lock on the LockInstance named lock1 then release it when your done... simple as that!

// Get the lock
err = lock.Lock()
if err != nil {
	panic("Failed to get lock: %+v", err)
}
fmt.Printf("Acquired lease: %s", lock.LockID.String())

// Release the lock
err = lock.Unlock()
if err != nil {
	panic(err)
}
   

If you look at the storage account your using you'll see a container called azlockcontainer under it will be empty blobs for each of the locks you have created. You can configure Azure Storage Lifecycle Management to clear these down periodically

Advanced

You can define custom behaviors which change how locking behaves, by default the following behaviors are used:

• PanicOnLostLock: If a lock is lost before being unlocked go will panic
• AutoRenewLocks: Once obtained a lock will be renewed until unlocked
• UnlockWhenContextCancelled: If the context used is canceled a temporary context is created and an unlock will be attempted. The temporary context is allowed 5sec to complete.
• RetryObtainingLock: If the lock is held elsewhere the Lock func will retry acquiring it for 10x the LockTTL

You can create your own and pass them into the NewLockInstance. Beware, when you pass in a behavior all default behaviors are ignored.

To see an example of a behavior look at AutoRenewLock