Copy and transform data in Azure Blob storage by using Azure Data Factory

• 11/13/2019
• 22 minutes to read
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This article outlines how to use Copy Activity in Azure Data Factory to copy data from and to Azure Blob storage, and use Data Flow to transform data in Azure Blob storage. To learn about Azure Data Factory, read the introductory article.

Supported capabilities

This Azure Blob connector is supported for the following activities:

• Copy activity with supported source/sink matrix
• Mapping data flow
• Lookup activity
• GetMetadata activity
• Delete activity

For Copy activity, this Blob storage connector supports:

• Copying blobs to and from general-purpose Azure storage accounts and hot/cool blob storage.
• Copying blobs by using account key, service shared access signature, service principal or managed identities for Azure resources authentications.
• Copying blobs from block, append, or page blobs and copying data to only block blobs.
• Copying blobs as is or parsing or generating blobs with supported file formats and compression codecs.

Get started

You can use one of the following tools or SDKs to use the copy activity with a pipeline. Select a link for step-by-step instructions:

• Copy data tool
• Azure portal
• .NET SDK
• Python SDK
• Azure PowerShell
• REST API
• Azure Resource Manager template

The following sections provide details about properties that are used to define Data Factory entities specific to Blob storage.

Linked service properties

Azure Blob connector support the following authentication types, refer to the corresponding section on details:

• Account key authentication
• Shared access signature authentication
• Service principal authentication
• Managed identities for Azure resources authentication

Account key authentication

To use storage account key authentication, the following properties are supported:

Example:

{
    "name": "AzureBlobStorageLinkedService",
    "properties": {
        "type": "AzureBlobStorage",
        "typeProperties": {
            "connectionString": {
                "type": "SecureString",
                "value": "DefaultEndpointsProtocol=https;AccountName=<accountname>;AccountKey=<accountkey>"
            }
        },
        "connectVia": {
            "referenceName": "<name of Integration Runtime>",
            "type": "IntegrationRuntimeReference"
        }
    }
}

Example: store account key in Azure Key Vault

{
    "name": "AzureBlobStorageLinkedService",
    "properties": {
        "type": "AzureBlobStorage",
        "typeProperties": {
            "connectionString": {
                "type": "SecureString",
                "value": "DefaultEndpointsProtocol=https;AccountName=<accountname>;"
            },
            "accountKey": { 
                "type": "AzureKeyVaultSecret", 
                "store": { 
                    "referenceName": "<Azure Key Vault linked service name>", 
                    "type": "LinkedServiceReference" 
                }, 
                "secretName": "<secretName>" 
            }
        },
        "connectVia": {
            "referenceName": "<name of Integration Runtime>",
            "type": "IntegrationRuntimeReference"
        }            
    }
}

Shared access signature authentication

A shared access signature provides delegated access to resources in your storage account. You can use a shared access signature to grant a client limited permissions to objects in your storage account for a specified time. You don't have to share your account access keys. The shared access signature is a URI that encompasses in its query parameters all the information necessary for authenticated access to a storage resource. To access storage resources with the shared access signature, the client only needs to pass in the shared access signature to the appropriate constructor or method. For more information about shared access signatures, see Shared access signatures: Understand the shared access signature model.

To use shared access signature authentication, the following properties are supported:

Example:

{
    "name": "AzureBlobStorageLinkedService",
    "properties": {
        "type": "AzureBlobStorage",
        "typeProperties": {
            "sasUri": {
                "type": "SecureString",
                "value": "<SAS URI of the Azure Storage resource e.g. https://<container>.blob.core.windows.net/?sv=<storage version>&amp;st=<start time>&amp;se=<expire time>&amp;sr=<resource>&amp;sp=<permissions>&amp;sip=<ip range>&amp;spr=<protocol>&amp;sig=<signature>>"
            }
        },
        "connectVia": {
            "referenceName": "<name of Integration Runtime>",
            "type": "IntegrationRuntimeReference"
        }
    }
}

Example: store account key in Azure Key Vault

{
    "name": "AzureBlobStorageLinkedService",
    "properties": {
        "type": "AzureBlobStorage",
        "typeProperties": {
            "sasUri": {
                "type": "SecureString",
                "value": "<SAS URI of the Azure Storage resource without token e.g. https://<container>.blob.core.windows.net/>"
            },
            "sasToken": { 
                "type": "AzureKeyVaultSecret", 
                "store": { 
                    "referenceName": "<Azure Key Vault linked service name>", 
                    "type": "LinkedServiceReference" 
                }, 
                "secretName": "<secretName>" 
            }
        },
        "connectVia": {
            "referenceName": "<name of Integration Runtime>",
            "type": "IntegrationRuntimeReference"
        }
    }
}

When you create a shared access signature URI, consider the following points:

• Set appropriate read/write permissions on objects based on how the linked service (read, write, read/write) is used in your data factory.
• Set Expiry time appropriately. Make sure that the access to Storage objects doesn't expire within the active period of the pipeline.
• The URI should be created at the right container/blob based on the need. A shared access signature URI to a blob allows Data Factory to access that particular blob. A shared access signature URI to a Blob storage container allows Data Factory to iterate through blobs in that container. To provide access to more or fewer objects later, or to update the shared access signature URI, remember to update the linked service with the new URI.

Service principal authentication

For Azure Storage service principal authentication in general, refer to Authenticate access to Azure Storage using Azure Active Directory.

To use service principal authentication, follow these steps:

1. Register an application entity in Azure Active Directory (Azure AD) by following Register your application with an Azure AD tenant. Make note of the following values, which you use to define the linked service:

   • Application ID
   • Application key
   • Tenant ID

2. Grant the service principal proper permission in Azure Blob storage. Refer to Manage access rights to Azure Storage data with RBAC with more details on the roles.

   • As source, in Access control (IAM), grant at least Storage Blob Data Reader role.
   • As sink, in Access control (IAM), grant at least Storage Blob Data Contributor role.

These properties are supported for an Azure Blob storage linked service:

Example:

{
    "name": "AzureBlobStorageLinkedService",
    "properties": {
        "type": "AzureBlobStorage",
        "typeProperties": {            
            "serviceEndpoint": "https://<accountName>.blob.core.windows.net/",
            "servicePrincipalId": "<service principal id>",
            "servicePrincipalKey": {
                "type": "SecureString",
                "value": "<service principal key>"
            },
            "tenant": "<tenant info, e.g. microsoft.onmicrosoft.com>" 
        },
        "connectVia": {
            "referenceName": "<name of Integration Runtime>",
            "type": "IntegrationRuntimeReference"
        }
    }
}

Managed identities for Azure resources authentication

A data factory can be associated with a managed identity for Azure resources, which represents this specific data factory. You can directly use this managed identity for Blob storage authentication similar to using your own service principal. It allows this designated factory to access and copy data from/to your Blob storage.

Refer to Authenticate access to Azure Storage using Azure Active Directory for Azure Storage authentication in general. To use managed identities for Azure resources authentication, follow these steps:

1. Retrieve data factory managed identity information by copying the value of "SERVICE IDENTITY APPLICATION ID" generated along with your factory.

2. Grant the managed identity proper permission in Azure Blob storage. Refer to Manage access rights to Azure Storage data with RBAC with more details on the roles.

   • As source, in Access control (IAM), grant at least Storage Blob Data Reader role.
   • As sink, in Access control (IAM), grant at least Storage Blob Data Contributor role.

These properties are supported for an Azure Blob storage linked service:

Example:

{
    "name": "AzureBlobStorageLinkedService",
    "properties": {
        "type": "AzureBlobStorage",
        "typeProperties": {            
            "serviceEndpoint": "https://<accountName>.blob.core.windows.net/"
        },
        "connectVia": {
            "referenceName": "<name of Integration Runtime>",
            "type": "IntegrationRuntimeReference"
        }
    }
}

Dataset properties

For a full list of sections and properties available for defining datasets, see the Datasets article.

Azure Data Factory support the following file formats. Refer to each article on format-based settings.

• Avro format
• Binary format
• Delimited text format
• JSON format
• ORC format
• Parquet format

The following properties are supported for Azure Blob under location settings in format-based dataset:

Example:

{
    "name": "DelimitedTextDataset",
    "properties": {
        "type": "DelimitedText",
        "linkedServiceName": {
            "referenceName": "<Azure Blob Storage linked service name>",
            "type": "LinkedServiceReference"
        },
        "schema": [ < physical schema, optional, auto retrieved during authoring > ],
        "typeProperties": {
            "location": {
                "type": "AzureBlobStorageLocation",
                "container": "containername",
                "folderPath": "folder/subfolder"
            },
            "columnDelimiter": ",",
            "quoteChar": "\"",
            "firstRowAsHeader": true,
            "compressionCodec": "gzip"
        }
    }
}

Legacy dataset model

Example:

{
    "name": "AzureBlobDataset",
    "properties": {
        "type": "AzureBlob",
        "linkedServiceName": {
            "referenceName": "<Azure Blob storage linked service name>",
            "type": "LinkedServiceReference"
        },
        "typeProperties": {
            "folderPath": "mycontainer/myfolder",
            "fileName": "*",
            "modifiedDatetimeStart": "2018-12-01T05:00:00Z",
            "modifiedDatetimeEnd": "2018-12-01T06:00:00Z",
            "format": {
                "type": "TextFormat",
                "columnDelimiter": ",",
                "rowDelimiter": "\n"
            },
            "compression": {
                "type": "GZip",
                "level": "Optimal"
            }
        }
    }
}

Copy activity properties

For a full list of sections and properties available for defining activities, see the Pipelines article. This section provides a list of properties supported by the Blob storage source and sink.

Blob storage as a source type

Azure Data Factory support the following file formats. Refer to each article on format-based settings.

• Avro format
• Binary format
• Delimited text format
• JSON format
• ORC format
• Parquet format

The following properties are supported for Azure Blob under storeSettings settings in format-based copy source:

Example:

"activities":[
    {
        "name": "CopyFromBlob",
        "type": "Copy",
        "inputs": [
            {
                "referenceName": "<Delimited text input dataset name>",
                "type": "DatasetReference"
            }
        ],
        "outputs": [
            {
                "referenceName": "<output dataset name>",
                "type": "DatasetReference"
            }
        ],
        "typeProperties": {
            "source": {
                "type": "DelimitedTextSource",
                "formatSettings":{
                    "type": "DelimitedTextReadSetting",
                    "skipLineCount": 10
                },
                "storeSettings":{
                    "type": "AzureBlobStorageReadSetting",
                    "recursive": true,
                    "wildcardFolderPath": "myfolder*A",
                    "wildcardFileName": "*.csv"
                }
            },
            "sink": {
                "type": "<sink type>"
            }
        }
    }
]

Legacy source model

Example:

"activities":[
    {
        "name": "CopyFromBlob",
        "type": "Copy",
        "inputs": [
            {
                "referenceName": "<Azure Blob input dataset name>",
                "type": "DatasetReference"
            }
        ],
        "outputs": [
            {
                "referenceName": "<output dataset name>",
                "type": "DatasetReference"
            }
        ],
        "typeProperties": {
            "source": {
                "type": "BlobSource",
                "recursive": true
            },
            "sink": {
                "type": "<sink type>"
            }
        }
    }
]

Blob storage as a sink type

Azure Data Factory support the following file formats. Refer to each article on format-based settings.

• Avro format
• Binary format
• Delimited text format
• JSON format
• ORC format
• Parquet format

The following properties are supported for Azure Blob under storeSettings settings in format-based copy sink:

Example:

"activities":[
    {
        "name": "CopyFromBlob",
        "type": "Copy",
        "inputs": [
            {
                "referenceName": "<input dataset name>",
                "type": "DatasetReference"
            }
        ],
        "outputs": [
            {
                "referenceName": "<Parquet output dataset name>",
                "type": "DatasetReference"
            }
        ],
        "typeProperties": {
            "source": {
                "type": "<source type>"
            },
            "sink": {
                "type": "ParquetSink",
                "storeSettings":{
                    "type": "AzureBlobStorageWriteSetting",
                    "copyBehavior": "PreserveHierarchy"
                }
            }
        }
    }
]

Legacy sink model

Example:

"activities":[
    {
        "name": "CopyToBlob",
        "type": "Copy",
        "inputs": [
            {
                "referenceName": "<input dataset name>",
                "type": "DatasetReference"
            }
        ],
        "outputs": [
            {
                "referenceName": "<Azure Blob output dataset name>",
                "type": "DatasetReference"
            }
        ],
        "typeProperties": {
            "source": {
                "type": "<source type>"
            },
            "sink": {
                "type": "BlobSink",
                "copyBehavior": "PreserveHierarchy"
            }
        }
    }
]

Folder and file filter examples

This section describes the resulting behavior of the folder path and file name with wildcard filters.

Some recursive and copyBehavior examples

This section describes the resulting behavior of the Copy operation for different combinations of recursive and copyBehavior values.

Mapping data flow properties

Learn details from source transformation and sink transformation in mapping data flow.

Lookup activity properties

To learn details about the properties, check Lookup activity.

GetMetadata activity properties

To learn details about the properties, check GetMetadata activity

Delete activity properties

To learn details about the properties, check Delete activity

Next steps

For a list of data stores supported as sources and sinks by the copy activity in Data Factory, see Supported data stores.