Azure Blob Storage binding spec

Detailed documentation on the Azure Blob Storage binding component

Setup Dapr component

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: <NAME>
  namespace: <NAMESPACE>
spec:
  type: bindings.azure.blobstorage
  version: v1
  metadata:
  - name: storageAccount
    value: myStorageAccountName
  - name: storageAccessKey
    value: ***********
  - name: container
    value: container1

• storageAccount is the Blob Storage account name.
• storageAccessKey is the Blob Storage access key.
• container is the name of the Blob Storage container to write to.
• decodeBase64 optional configuration to decode base64 file content before saving to Blob Storage. (In case of saving a file with binary content). “true” is the only allowed positive value. Other positive variations like “True” are not acceptable.

Warning

The above example uses secrets as plain strings. It is recommended to use a secret store for the secrets as described here.

Output Binding Supported Operations

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"
}

Example:

We escape since ‘ is not supported on Windows On Windows, utilize CMD (PowerShell has different escaping mechanism)

Saving to a random generated UUID file

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

Saving to a specific file

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

Saving a file

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>
  namespace: <NAMESPACE>
spec:
  type: bindings.azure.blobstorage
  version: v1
  metadata:
  - name: storageAccount
    value: myStorageAccountName
  - name: storageAccessKey
    value: ***********
  - name: container
    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>

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"
  }
}

Example:

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

Response

The response body will contain the value stored in the blob object.

Metadata information

By default the Azure Blob Storage output binding will auto generate a UUID as blob filename and not assign 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 contract:

{
    "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"
}

Related links

• Bindings building block
• How-To: Trigger application with input binding
• How-To: Use bindings to interface with external resources
• Bindings API reference

Last modified February 16, 2021: Merge pull request #1235 from dapr/update-v0.11 (b4e9fbb)