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Copy data from Google Cloud Storage to Azure Storage by using AzCopy

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AzCopy is a command-line utility that you can use to copy blobs or files to or from a storage account. This article helps you copy objects, directories, and buckets from Google Cloud Storage to Azure Blob Storage by using AzCopy.

Choose how you'll provide authorization credentials

  • To authorize with Azure Storage, use Microsoft Entra ID or a Shared Access Signature (SAS) token.

  • To authorize with Google Cloud Storage, use a service account key.

Authorize with Azure Storage

See the Get started with AzCopy article to download AzCopy and learn about the ways that you can provide authorization credentials to the storage service.

Note

The examples in this article assume that you've provided authorization credentials by using Microsoft Entra ID.

If you'd rather use a SAS token to authorize access to blob data, then you can append that token to the resource URL in each AzCopy command. For example: 'https://<storage-account-name>.blob.core.windows.net/<container-name><SAS-token>'.

Authorize with Google Cloud Storage

To authorize with Google Cloud Storage, you'll use a service account key. For information about how to create a service account key, see Creating and managing service account keys.

After you've obtained a service key, set the GOOGLE_APPLICATION_CREDENTIALS environment variable to absolute path to the service account key file:

Operating system Command
Windows set GOOGLE_APPLICATION_CREDENTIALS=<path-to-service-account-key>
Linux export GOOGLE_APPLICATION_CREDENTIALS=<path-to-service-account-key>
macOS export GOOGLE_APPLICATION_CREDENTIALS=<path-to-service-account-key>

Copy objects, directories, and buckets

AzCopy uses the Put Block From URL API, so data is copied directly between Google Cloud Storage and storage servers. These copy operations don't use the network bandwidth of your computer.

Tip

The examples in this section enclose path arguments with single quotes (''). Use single quotes in all command shells except for the Windows Command Shell (cmd.exe). If you're using a Windows Command Shell (cmd.exe), enclose path arguments with double quotes ("") instead of single quotes ('').

These examples also work with accounts that have a hierarchical namespace. Multi-protocol access on Data Lake Storage enables you to use the same URL syntax (blob.core.windows.net) on those accounts.

Copy an object

Use the same URL syntax (blob.core.windows.net) for accounts that have a hierarchical namespace.

Syntax

azcopy copy 'https://storage.cloud.google.com/<bucket-name>/<object-name>' 'https://<storage-account-name>.blob.core.windows.net/<container-name>/<blob-name>'

Example

azcopy copy 'https://storage.cloud.google.com/mybucket/myobject' 'https://mystorageaccount.blob.core.windows.net/mycontainer/myblob'

Copy a directory

Use the same URL syntax (blob.core.windows.net) for accounts that have a hierarchical namespace.

Syntax

azcopy copy 'https://storage.cloud.google.com/<bucket-name>/<directory-name>' 'https://<storage-account-name>.blob.core.windows.net/<container-name>/<directory-name>' --recursive=true

Example

azcopy copy 'https://storage.cloud.google.com/mybucket/mydirectory' 'https://mystorageaccount.blob.core.windows.net/mycontainer/mydirectory' --recursive=true

Note

This example appends the --recursive flag to copy files in all sub-directories.

Copy the contents of a directory

You can copy the contents of a directory without copying the containing directory itself by using the wildcard symbol (*).

Syntax

azcopy copy 'https://storage.cloud.google.com/<bucket-name>/<directory-name>/*' 'https://<storage-account-name>.blob.core.windows.net/<container-name>/<directory-name>' --recursive=true

Example

azcopy copy 'https://storage.cloud.google.com/mybucket/mydirectory/*' 'https://mystorageaccount.blob.core.windows.net/mycontainer/mydirectory' --recursive=true

Copy a Cloud Storage bucket

Use the same URL syntax (blob.core.windows.net) for accounts that have a hierarchical namespace.

Syntax

azcopy copy 'https://storage.cloud.google.com/<bucket-name>' 'https://<storage-account-name>.blob.core.windows.net' --recursive=true

Example

azcopy copy 'https://storage.cloud.google.com/mybucket' 'https://mystorageaccount.blob.core.windows.net' --recursive=true

Copy all buckets in a Google Cloud project

First, set the GOOGLE_CLOUD_PROJECT to project ID of Google Cloud project.

Use the same URL syntax (blob.core.windows.net) for accounts that have a hierarchical namespace.

Syntax

azcopy copy 'https://storage.cloud.google.com/' 'https://<storage-account-name>.blob.core.windows.net' --recursive=true

Example

azcopy copy 'https://storage.cloud.google.com/' 'https://mystorageaccount.blob.core.windows.net' --recursive=true

Copy a subset of buckets in a Google Cloud project

First, set the GOOGLE_CLOUD_PROJECT to project ID of Google Cloud project.

Copy a subset of buckets by using a wildcard symbol (*) in the bucket name. Use the same URL syntax (blob.core.windows.net) for accounts that have a hierarchical namespace.

Syntax

azcopy copy 'https://storage.cloud.google.com/<bucket*name>' 'https://<storage-account-name>.blob.core.windows.net' --recursive=true

Example

azcopy copy 'https://storage.cloud.google.com/my*bucket' 'https://mystorageaccount.blob.core.windows.net' --recursive=true

Handle differences in bucket naming rules

Google Cloud Storage has a different set of naming conventions for bucket names as compared to Azure blob containers. You can read about them here. If you choose to copy a group of buckets to an Azure storage account, the copy operation might fail because of naming differences.

AzCopy handles three of the most common issues that can arise; buckets that contain periods, buckets that contain consecutive hyphens, and buckets that contain underscores. Google Cloud Storage bucket names can contain periods and consecutive hyphens, but a container in Azure can't. AzCopy replaces periods with hyphens and consecutive hyphens with a number that represents the number of consecutive hyphens (For example: a bucket named my----bucket becomes my-4-bucket. If the bucket name has an underscore (_), then AzCopy replaces the underscore with a hyphen. For example, a bucket named my_bucket becomes my-bucket.

Handle differences in object naming rules

Google Cloud Storage has a different set of naming conventions for object names as compared to Azure blobs. You can read about them here.

Azure Storage does not permit object names (or any segment in the virtual directory path) to end with trailing dots (For example my-bucket...). Trailing dots are trimmed off when the copy operation is performed.

Handle differences in object metadata

Google Cloud Storage and Azure allow different sets of characters in the names of object keys. You can read about metadata in Google Cloud Storage here. On the Azure side, blob object keys adhere to the naming rules for C# identifiers.

As part of an AzCopy copy command, you can provide a value for optional the s2s-handle-invalid-metadata flag that specifies how you would like to handle files where the metadata of the file contains incompatible key names. The following table describes each flag value.

Flag value Description
ExcludeIfInvalid (Default option) The metadata isn't included in the transferred object. AzCopy logs a warning.
FailIfInvalid Objects aren't copied. AzCopy logs an error and includes that error in the failed count that appears in the transfer summary.
RenameIfInvalid AzCopy resolves the invalid metadata key, and copies the object to Azure using the resolved metadata key value pair. To learn exactly what steps AzCopy takes to rename object keys, see the How AzCopy renames object keys section below. If AzCopy is unable to rename the key, then the object won't be copied.

How AzCopy renames object keys

AzCopy performs these steps:

  1. Replaces invalid characters with '_'.

  2. Adds the string rename_ to the beginning of a new valid key.

    This key will be used to save the original metadata value.

  3. Adds the string rename_key_ to the beginning of a new valid key. This key will be used to save original metadata invalid key. You can use this key to try to recover the metadata in Azure side since metadata key is preserved as a value on the Blob storage service.

Next steps

Find more examples in these articles:

See these articles to configure settings, optimize performance, and troubleshoot issues: