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Object Storage - Azure Blob Storage

An Azure Blob Storage implementation of the ObjectStorage protocol. It provides optional Integrant keys.

Table of contents

Installation

Clojars Project

Usage

Getting an AzureBlobStorage record

Using Integrant

The library provides a single Integrant key, :dev.gethop.object-storage/azure-blob-storage, that returns a AzureBlobStorage record that can be used to perform ObjectStorage operations on a given Azure Blob Storage Container.

The key initialization expects the following keys:

  • :account: A map with the following keys:
    • connection-string: The Access Key Connection String of the account where you want to perform object operations.
  • :container: A map with the following keys:
    • name: The name of the Azure Blob Storage Container where you want to perform object operations.
  • :presigned-url-lifespan: Lifespan for presigned URLs. It is specified in minutes, and the default values is one hour.

Example configuration, with a presigned URL life span of 30 minutes:

 :dev.gethop.object-storage/azure-blob-storage {:account {:connection-string "DefaultEndpointsProtocol=https;AccountName=example;AccountKey=WoSTHF3LrMqVyWwOhkkxnZqsxCsneZjkqsJdmE7CsJk;EndpointSuffix=core.windows.net"}
                                                :container {:name "example"}
                                                :presigned-url-lifespan 30}

Non Integrant projects

The library can also be used without Integrant. Just call the dev.gethop.object-storage.azure-blob-storage/init-record function with the same options you would use to initialize the Integrant key.

(require '[dev.gethop.object-storage.azure-blob-storage :as abs])
(abs/init-record {:account {:connection-string "DefaultEndpointsProtocol=https;AccountName=example;AccountKey=WoSTHF3LrMqVyWwOhkkxnZqsxCsneZjkqsJdmE7CsJk;EndpointSuffix=core.windows.net"}
                  :container {:name "example"}
                  :presigned-url-lifespan 30})

Performing Azure Blob storage object operations

Require the dev.gethop.object-storage.core namespace to get the ObjectStorage protocol definition.

user> (require '[dev.gethop.object-storage.core :as object-storage])
nil

Then, initialize the Integrant key to get the Azure Blob Storage boundary AzureBlobStorage record:

user> (def config {:account {:connection-string "DefaultEndpointsProtocol=https;AccountName=example;AccountKey=WoSTHF3LrMqVyWwOhkkxnZqsxCsneZjkqsJdmE7CsJk;EndpointSuffix=core.windows.net"}
                  :container {:name "example"}
                  :presigned-url-lifespan 30})
#'user/config
user> (require '[dev.gethop.object-storage.azure-blob-storage]
               '[integrant.core :as ig])
nil
user> (def record (ig/init-key :dev.gethop.object-storage/azure-blob-storage config))
#'user/object-storage-record

Once we have the protocol in place, we can use the AzureBlobStorage record to perform the following operations.

put-object

(put-object object-storage-record object-id object)
  • description: Uploads an object to Azure Blob Storage with object-id as its Blob name.
  • parameters:
    • record: An AzureBlobStorage record.
    • object-id: The name/path of the Blob to upload.
    • object: The file to upload (as a java.io.File-compatible value).
  • return value: a map with the following keys:
    • :success?: boolean stating if the operation was successful or not.
    • :error-details: a map with additional details on the problem encountered while trying to upload the object.

An example:

user> (require '[clojure.java.io :as io])
user> (object-storage/put-object record "object-id" (io/file "some-existing-file"))
{:success? true}
(put-object object-storage-record object-id object opts)
  • description: Uploads an object to Azure Blob Storage with object-id as its Blob name.
  • parameters:
    • record: An AzureBlobStorage record.
    • object-id: The name/path of the Blob to upload.
    • object: The file to upload. It can be either a java.io.File-compatible value or an java.io.InputStream-compatible value. In the latter case, if you know the size of the content in the InputStream, add the :metadata key to the opts map.
  • return value: a map with the following keys:
  • `opts: A map of options. Currently supported option keys are:
    • metadata: It is a map with the following supported keys:
      • :object-size: The size, in bytes, of the object passed in as an InputStream.
    • :success?: boolean stating if the operation was successful or not.
    • :error-details: a map with additional details on the problem encountered while trying to upload the object.

An example:

user> (let [object-content (.getBytes "Test")
            object-size (count object-content)]
        (object-storage/put-object record
                                   "object-id"
                                   (io/input-stream object-content)
                                   {:metadata {:object-size object-size}}))
{:success? true}

copy-object

(copy-object object-storage-record source-object-id destination-object-id)
  • description: Copies an object from AzureBlobStorage into the same Container.
  • parameters:
    • record: An AzureBlobStorage record.
    • source-object-id: The name/path of the Blob to copy.
    • destination-object-id: The destination Blob path/name to copy the source to.
  • return value: a map with the following keys:
    • :success?: boolean stating if the operation was successful or not.
    • :error-details: a map with additional details on the problem encountered while trying to copy the object.

Example:

user> (object-storage/copy-object record "some-existing-source-object-id" "new-destination-object-id")
{:success? true}

Failed operation when trying to copy a Blob that doesn't exist:

user> (object-storage/copy-object record "non-existing-object-id" "object-id")
{:success? false,
 :error-details
 {:body
  "<?xml version=\"1.0\" encoding=\"utf-8\"?><Error><Code>BlobNotFound</Code><Message>The specified blob does not exist.\nRequestId:11ae648f-001e-0067-22b1-08f49e000000\nTime:2023-10-27T08:40:58.9785865Z</Message></Error>",
  :headers
  {:content-length "215",
   :content-type "application/xml",
   :date "Fri, 27 Oct 2023 08:40:58 GMT",
   :server "Windows-Azure-Blob/1.0 Microsoft-HTTPAPI/2.0",
   :x-ms-error-code "BlobNotFound",
   :x-ms-request-id "11ae648f-001e-0067-22b1-08f49e000000",
   :x-ms-version "2019-02-02"},
  :status 404}}

get-object

(get-object object-storage-record object-id)
  • description: Retrieves an object from Azure Blob Storage.
  • parameters:
    • record: An AzureBlobStorage record.
    • object-id: The name/path of the Blob to retrieve.
  • return value: a map with the following keys:
    • :success?: boolean stating if the operation was successful or not.
    • :object: If the operation was successful, this key contains an InputStream-compatible stream, on the desired object.
    • :error-details: a map with additional details on the problem encountered while trying to retrieve the object.

Example:

user> (object-storage/get-object record "object-id" "example.txt")
{:success? true,
 :object
 #object[org.httpkit.BytesInputStream 0x1e0830ba "BytesInputStream[len=4]"]}

Example when target object doesn't exist:

user> (object-storage/get-object record "non-existing-object-id" "example.txt")
{:success? false,
 :error-details
 {:body
  "<?xml version=\"1.0\" encoding=\"utf-8\"?><Error><Code>BlobNotFound</Code><Message>The specified blob does not exist.\nRequestId:11af9480-001e-0067-48b1-08f49e000000\nTime:2023-10-27T08:42:42.4744107Z</Message></Error>",
  :headers
  {:content-length "215",
   :content-type "application/xml",
   :date "Fri, 27 Oct 2023 08:42:41 GMT",
   :server "Windows-Azure-Blob/1.0 Microsoft-HTTPAPI/2.0",
   :x-ms-error-code "BlobNotFound",
   :x-ms-request-id "11af9480-001e-0067-48b1-08f49e000000",
   :x-ms-version "2019-02-02"},
  :status 404}}

get-object-url

(get-object-url object-storage-record object-id)
  • description: Gets a presigned URL that can be used to get the specified object without authentication. The URL lifespan is specified in the AzureBlobStorage record initialization.
  • parameters:
    • record: An AzureBlobStorage record.
    • object-id: The name/path of the object in the Blob Container.
  • return value: a map with the following keys:
    • :success?: boolean stating if the operation was successful or not.
    • :object-url: If the operation was successful, this key contains a string with a presigned URL that can be used to get the specified object without authentication, but only within the configured lifespan. In addition, the presigned URL is only valid for GET requests.
    • :error-details: a map with additional details on the problem encountered while trying to create the presigned URL.

Example:

user> (object-storage/get-object-url record "object-id")
{:success? true,
 :object-url
 "https://gethop.blob.core.windows.net/object-storage-library-integration-tests/object-id?spr=https&sv=2020-12-06&sr=b&sp=r&se=2023-10-27T08%3A48%3A34Z&rscd=attachment&rsct=application%2Foctet-stream&sig=Jf6qM0oW%2BJpHe9%2FHErvcIhcAlxaP5o69xLfp3vr3p1Y%3D"}
(get-object-url object-storage-record object-id opts)
  • description: Gets a presigned URL that can be used to access the specified object without authentication, using special options. The URL lifespan is specified in the AzureBlobStorage record initialization.
  • parameters:
    • record: An AzureBlobStorage record.
    • object-id: The name/path of the object in the Blob Container.
    • opts: A map of options. Currently supported option keys are:
      • :method: Specifies the operation that we want to use with the presigned URL. It can be one of the following:
        • :create: Allows using a HTTP PUT request.
        • :read: Allows using a HTTP GET request.
        • :update: Allows using a HTTP PUT request.
        • :delete: Allows using a HTTP DELETE request.
      • :filename: Specifies the filename that will be included in the "Content-Disposition" header for :read requests. It allows retrieving the object with a different name that the Blob name/path it was stored under.
      • :content-type: Specifies the value that will be included in the "Content-Type" header. Uses "application/octet-stream" as default if unspecified.
      • :content-disposition: Specifies the value that will be included in the "Content-Disposition" header. Has to be either :inline or :attachment. Defaults to :attachment.
      • :object-public-url?: A boolean that specifies if the URL returned by this function should be a publicly accessible one (if set to a truthy value) or a pre-signed URL (if set to a falsy value). If set to a truthy value, the object should be publicly accessible for the returned URL to work. This key is optional and, if not specified, defaults to a falsy value.
        Due to Azure's lack of compatibility, if this key is set to a truthy value these other keys will be ignored:
        • :filename
        • :content-type
        • :content-disposition
  • return value: a map with the following keys:
    • :success?: boolean stating if the operation was successful or not.
    • :object-url: If the operation was successful, this key contains a string with a presigned URL that can be used to get the specified object without authentication, but only within the configured lifespan. In addition, the presigned URL is only valid for GET requests.
    • :error-details: a map with additional details on the problem encountered while trying to create the presigned URL.

Example of a presigned URL where a custom download file-name is specified:

user> (object-storage/get-object-url record "object-id" {:filename "other-arbitrary-filename"})
{:success? true,
 :object-url
 "https://gethop.blob.core.windows.net/object-storage-library-integration-tests/object-id?spr=https&sv=2020-12-06&sr=b&sp=r&se=2023-10-27T08%3A50%3A40Z&rscd=attachment%3B+filename%3Dother-arbitrary-filename&rsct=application%2Foctet-stream&sig=Skvc%2FTQrMbV59S8i6DWWFZCG4in3zf1I1GUiHKlqYb4%3D"}

list-objects

(list-objects object-storage-record parent-object-id)
  • description: Gets a list of children objects from a given Blob storage path.
  • parameters:
    • record: An AzureBlobStorage record.
    • parent-object-id: The key of the object in the Azure Blob Storage to access.
  • return value: a map with the following keys:
    • :success?: boolean stating if the operation was successful or not.
    • :objects: If the operation was successful, this key contains a collection of maps.Each map represents a children object. Every object has 3 attributes: object-id, last-modified and size.
    • :error-details: a map with additional details on the problem encountered while trying retrieve the list of objects.

Example:

user> (object-storage/list-objects record nil)
{:success? true,
 :objects
 ({:object-id "object-id",
   :size 4,
   :last-modified
   #object[java.time.ZonedDateTime 0x233711e1 "2023-10-27T08:40:27Z"]})}

delete-object

(delete-object object-storage-record object-id)
  • description: Deletes the object with key object-id from Azure Blob Storage.
  • parameters:
    • record: An AzureBlobStorage record.
    • object-id: The name/path of the object in the Azure Blob Storage Container that we want to delete.
  • return value: a map with the following keys:
    • :success?: boolean stating if the operation was successful or not.
    • :error-details: a map with additional details on the problem encountered while trying to retrieve the object.

Example:

user> (object-storage/delete-object record "object-id")
{:success? true}

Example with error when object-id doesn't exist:

user> (object-storage/delete-object record "non-existing-object-id")
{:success? false,
 :error-details
 {:body
  "<?xml version=\"1.0\" encoding=\"utf-8\"?><Error><Code>BlobNotFound</Code><Message>The specified blob does not exist.\nRequestId:89177936-e01e-001d-4bb2-08e9de000000\nTime:2023-10-27T08:47:12.8146281Z</Message></Error>",
  :headers
  {:content-length "215",
   :content-type "application/xml",
   :date "Fri, 27 Oct 2023 08:47:12 GMT",
   :server "Windows-Azure-Blob/1.0 Microsoft-HTTPAPI/2.0",
   :x-ms-error-code "BlobNotFound",
   :x-ms-request-id "89177936-e01e-001d-4bb2-08e9de000000",
   :x-ms-version "2019-02-02"},
  :status 404}}

Testing

The library includes self-contained units tests, including some integration tests that depend on the Azure Blob Storage service. Those tests have the ^:integration metadata keyword associated to them, so you can exclude them from our unit tests runs.

If you want to run the integration tests, the following set of environment variables are needed:

  • TEST_AZURE_BLOB_STORAGE_ACCOUNT_CONNECTION_STRING: The Access Key connection string of the Azure Storage Account to be used when running the tests.
  • TEST_AZURE_BLOB_STORAGE_CONTAINER_NAME: The name of the Container to be used when running the tests.

License

Copyright (c) 2023 Magnet S. Coop

The source code for the library is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.

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