Azure Blob Storage binding spec

Detailed documentation on the Azure Blob Storage binding component

Component format

To setup Azure Blob Storage binding create a component of type bindings.azure.blobstorage. See this guide on how to create and apply a binding configuration.

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: <NAME>
spec:
  type: bindings.azure.blobstorage
  version: v1
  metadata:
  - name: accountName
    value: myStorageAccountName
  - name: accountKey
    value: ***********
  - name: containerName
    value: container1
# - name: decodeBase64
#   value: <bool>
# - name: getBlobRetryCount
#   value: <integer>
# - name: publicAccessLevel
#   value: <publicAccessLevel>

Spec metadata fields

Field Required Binding support Details Example
accountName Y Input/Output The name of the Azure Storage account "myexmapleaccount"
accountKey Y* Input/Output The access key of the Azure Storage account. Only required when not using Microsoft Entra ID authentication. "access-key"
containerName Y Output The name of the Blob Storage container to write to myexamplecontainer
endpoint N Input/Output Optional custom endpoint URL. This is useful when using the Azurite emulator or when using custom domains for Azure Storage (although this is not officially supported). The endpoint must be the full base URL, including the protocol (http:// or https://), the IP or FQDN, and optional port. "http://127.0.0.1:10000"
decodeBase64 N Output Configuration to decode base64 file content before saving to Blob Storage. (In case of saving a file with binary content). Defaults to false true, false
getBlobRetryCount N Output Specifies the maximum number of HTTP GET requests that will be made while reading from a RetryReader Defaults to 10 1, 2
publicAccessLevel N Output Specifies whether data in the container may be accessed publicly and the level of access (only used if the container is created by Dapr). Defaults to none blob, container, none

Microsoft Entra ID authentication

The Azure Blob Storage binding component supports authentication using all Microsoft Entra ID mechanisms. For further information and the relevant component metadata fields to provide depending on the choice of Microsoft Entra ID authentication mechanism, see the docs for authenticating to Azure.

Binding support

This component supports output binding with the following operations:

The Blob storage component’s input binding triggers and pushes events using Azure Event Grid.

Refer to the Reacting to Blob storage events guide for more set up and more information.

Create blob

To perform a create blob operation, invoke the Azure Blob Storage binding with a POST method and the following JSON body:

Note: by default, a random UUID is generated. See below for Metadata support to set the name

{
  "operation": "create",
  "data": "YOUR_CONTENT"
}

Examples

Save text to a random generated UUID blob

On Windows, utilize cmd prompt (PowerShell has different escaping mechanism)

curl -d "{ \"operation\": \"create\", \"data\": \"Hello World\" }" http://localhost:<dapr-port>/v1.0/bindings/<binding-name>


curl -d '{ "operation": "create", "data": "Hello World" }' \
      http://localhost:<dapr-port>/v1.0/bindings/<binding-name>
Save text to a specific blob

curl -d "{ \"operation\": \"create\", \"data\": \"Hello World\", \"metadata\": { \"blobName\": \"my-test-file.txt\" } }" \
      http://localhost:<dapr-port>/v1.0/bindings/<binding-name>


curl -d '{ "operation": "create", "data": "Hello World", "metadata": { "blobName": "my-test-file.txt" } }' \
      http://localhost:<dapr-port>/v1.0/bindings/<binding-name>
Save a file to a blob

To upload a file, encode it as Base64 and let the Binding know to deserialize it:

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: <NAME>
spec:
  type: bindings.azure.blobstorage
  version: v1
  metadata:
  - name: accountName
    value: myStorageAccountName
  - name: accountKey
    value: ***********
  - name: containerName
    value: container1
  - name: decodeBase64
    value: true

Then you can upload it as you would normally:


curl -d "{ \"operation\": \"create\", \"data\": \"YOUR_BASE_64_CONTENT\", \"metadata\": { \"blobName\": \"my-test-file.jpg\" } }" http://localhost:<dapr-port>/v1.0/bindings/<binding-name>


curl -d '{ "operation": "create", "data": "YOUR_BASE_64_CONTENT", "metadata": { "blobName": "my-test-file.jpg" } }' \
      http://localhost:<dapr-port>/v1.0/bindings/<binding-name>

Response

The response body will contain the following JSON:

{
   "blobURL": "https://<your account name>. blob.core.windows.net/<your container name>/<filename>"
}

Get blob

To perform a get blob operation, invoke the Azure Blob Storage binding with a POST method and the following JSON body:

{
  "operation": "get",
  "metadata": {
    "blobName": "myblob",
    "includeMetadata": "true"
  }
}

The metadata parameters are:

  • blobName - the name of the blob
  • includeMetadata- (optional) defines if the user defined metadata should be returned or not, defaults to: false

Example


curl -d '{ \"operation\": \"get\", \"metadata\": { \"blobName\": \"myblob\" }}' http://localhost:<dapr-port>/v1.0/bindings/<binding-name>


curl -d '{ "operation": "get", "metadata": { "blobName": "myblob" }}' \
      http://localhost:<dapr-port>/v1.0/bindings/<binding-name>

Response

The response body contains the value stored in the blob object. If enabled, the user defined metadata will be returned as HTTP headers in the form:

Metadata.key1: value1 Metadata.key2: value2

Delete blob

To perform a delete blob operation, invoke the Azure Blob Storage binding with a POST method and the following JSON body:

{
  "operation": "delete",
  "metadata": {
    "blobName": "myblob"
  }
}

The metadata parameters are:

  • blobName - the name of the blob
  • deleteSnapshots - (optional) required if the blob has associated snapshots. Specify one of the following two options:
    • include: Delete the base blob and all of its snapshots
    • only: Delete only the blob’s snapshots and not the blob itself

Examples

Delete blob

curl -d '{ \"operation\": \"delete\", \"metadata\": { \"blobName\": \"myblob\" }}' http://localhost:<dapr-port>/v1.0/bindings/<binding-name>


curl -d '{ "operation": "delete", "metadata": { "blobName": "myblob" }}' \
      http://localhost:<dapr-port>/v1.0/bindings/<binding-name>
Delete blob snapshots only

curl -d '{ \"operation\": \"delete\", \"metadata\": { \"blobName\": \"myblob\", \"deleteSnapshots\": \"only\" }}' http://localhost:<dapr-port>/v1.0/bindings/<binding-name>


curl -d '{ "operation": "delete", "metadata": { "blobName": "myblob", "deleteSnapshots": "only" }}' \
      http://localhost:<dapr-port>/v1.0/bindings/<binding-name>
Delete blob including snapshots

curl -d '{ \"operation\": \"delete\", \"metadata\": { \"blobName\": \"myblob\", \"deleteSnapshots\": \"include\" }}' http://localhost:<dapr-port>/v1.0/bindings/<binding-name>


curl -d '{ "operation": "delete", "metadata": { "blobName": "myblob", "deleteSnapshots": "include" }}' \
      http://localhost:<dapr-port>/v1.0/bindings/<binding-name>

Response

An HTTP 204 (No Content) and empty body will be retuned if successful.

List blobs

To perform a list blobs operation, invoke the Azure Blob Storage binding with a POST method and the following JSON body:

{
  "operation": "list",
  "data": {
    "maxResults": 10,
    "prefix": "file",
    "marker": "2!108!MDAwMDM1IWZpbGUtMDgtMDctMjAyMS0wOS0zOC01NS03NzgtMjEudHh0ITAwMDAyOCE5OTk5LTEyLTMxVDIzOjU5OjU5Ljk5OTk5OTlaIQ--",
    "include": {
      "snapshots": false,
      "metadata": true,
      "uncommittedBlobs": false,
      "copy": false,
      "deleted": false
    }
  }
}

The data parameters are:

  • maxResults - (optional) specifies the maximum number of blobs to return, including all BlobPrefix elements. If the request does not specify maxresults the server will return up to 5,000 items.
  • prefix - (optional) filters the results to return only blobs whose names begin with the specified prefix.
  • marker - (optional) a string value that identifies the portion of the list to be returned with the next list operation. The operation returns a marker value within the response body if the list returned was not complete. The marker value may then be used in a subsequent call to request the next set of list items.
  • include - (optional) Specifies one or more datasets to include in the response:
    • snapshots: Specifies that snapshots should be included in the enumeration. Snapshots are listed from oldest to newest in the response. Defaults to: false
    • metadata: Specifies that blob metadata be returned in the response. Defaults to: false
    • uncommittedBlobs: Specifies that blobs for which blocks have been uploaded, but which have not been committed using Put Block List, be included in the response. Defaults to: false
    • copy: Version 2012-02-12 and newer. Specifies that metadata related to any current or previous Copy Blob operation should be included in the response. Defaults to: false
    • deleted: Version 2017-07-29 and newer. Specifies that soft deleted blobs should be included in the response. Defaults to: false

Response

The response body contains the list of found blocks as also the following HTTP headers:

Metadata.marker: 2!108!MDAwMDM1IWZpbGUtMDgtMDctMjAyMS0wOS0zOC0zNC04NjctMTEudHh0ITAwMDAyOCE5OTk5LTEyLTMxVDIzOjU5OjU5Ljk5OTk5OTlaIQ-- Metadata.number: 10

  • marker - the next marker which can be used in a subsequent call to request the next set of list items. See the marker description on the data property of the binding input.
  • number - the number of found blobs

The list of blobs will be returned as JSON array in the following form:

[
  {
    "XMLName": {
      "Space": "",
      "Local": "Blob"
    },
    "Name": "file-08-07-2021-09-38-13-776-1.txt",
    "Deleted": false,
    "Snapshot": "",
    "Properties": {
      "XMLName": {
        "Space": "",
        "Local": "Properties"
      },
      "CreationTime": "2021-07-08T07:38:16Z",
      "LastModified": "2021-07-08T07:38:16Z",
      "Etag": "0x8D941E3593C6573",
      "ContentLength": 1,
      "ContentType": "application/octet-stream",
      "ContentEncoding": "",
      "ContentLanguage": "",
      "ContentMD5": "xMpCOKC5I4INzFCab3WEmw==",
      "ContentDisposition": "",
      "CacheControl": "",
      "BlobSequenceNumber": null,
      "BlobType": "BlockBlob",
      "LeaseStatus": "unlocked",
      "LeaseState": "available",
      "LeaseDuration": "",
      "CopyID": null,
      "CopyStatus": "",
      "CopySource": null,
      "CopyProgress": null,
      "CopyCompletionTime": null,
      "CopyStatusDescription": null,
      "ServerEncrypted": true,
      "IncrementalCopy": null,
      "DestinationSnapshot": null,
      "DeletedTime": null,
      "RemainingRetentionDays": null,
      "AccessTier": "Hot",
      "AccessTierInferred": true,
      "ArchiveStatus": "",
      "CustomerProvidedKeySha256": null,
      "AccessTierChangeTime": null
    },
    "Metadata": null
  }
]

Metadata information

By default the Azure Blob Storage output binding auto generates a UUID as the blob filename and is not assigned any system or custom metadata to it. It is configurable in the metadata property of the message (all optional).

Applications publishing to an Azure Blob Storage output binding should send a message with the following format:

{
    "data": "file content",
    "metadata": {
        "blobName"           : "filename.txt",
        "contentType"        : "text/plain",
        "contentMD5"         : "vZGKbMRDAnMs4BIwlXaRvQ==",
        "contentEncoding"    : "UTF-8",
        "contentLanguage"    : "en-us",
        "contentDisposition" : "attachment",
        "cacheControl"       : "no-cache",
        "custom"             : "hello-world"
    },
    "operation": "create"
}

Last modified November 1, 2024: edits to the blog storage binding (e828e466)