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Azure Storage Rest APIs🔗

🔑 1. What It Is🔗

The Azure Storage REST API allows you to programmatically perform operations on:

  • Blob storage (block, append, page blobs → includes ADLS Gen2)
  • Queue storage
  • Table storage (legacy, use Cosmos DB Table API now)
  • File shares (Azure Files)

Instead of SDKs (Python, .NET, Java, etc.), you can call storage endpoints directly via HTTPS.

🔑 2. REST API Endpoint Pattern🔗

Every request goes to:

https://<account_name>.blob.core.windows.net/<container>/<blob>?<optional_parameters>

Example (reading a file in ADLS Gen2):

GET https://mystorageaccount.blob.core.windows.net/mycontainer/myfolder/myfile.csv HTTP/1.1
x-ms-date: Mon, 15 Sep 2025 18:00:00 GMT
x-ms-version: 2023-11-03
Authorization: SharedKey mystorageaccount:<signature>

🔑 3. Authentication Methods🔗

You must authenticate every REST API request. Options:

  1. Shared Key (HMAC)

  2. Uses your storage account name + access key.

  3. You compute an HMAC signature for each request (Authorization: SharedKey <account>:<signature>).

  4. Very low-level but powerful.

  5. SAS (Shared Access Signature)

  6. Pre-signed URL with limited permissions (read/write/list/delete).

  7. Example:

    https://mystorageaccount.blob.core.windows.net/mycontainer/myfile.csv?sv=2023-11-03&ss=b&srt=o&sp=rw&se=2025-09-16T18:00Z&sig=<signature>
    * Great for temporary access (e.g., users, apps, third parties).

  8. OAuth 2.0 / Azure AD (Recommended)

  9. Use Azure AD service principal or managed identity.

  10. Add bearer token in header:

    Authorization: Bearer <access_token>

🔑 4. Common REST Operations (Blobs / ADLS Gen2)🔗

Container Operations🔗

  • Create Container

PUT https://<account>.blob.core.windows.net/<container>?restype=container
* List Containers

GET https://<account>.blob.core.windows.net/?comp=list

Blob/File Operations🔗

  • Upload Blob
PUT https://<account>.blob.core.windows.net/<container>/<blob>
x-ms-blob-type: BlockBlob

(Body contains file data)

  • Download Blob
GET https://<account>.blob.core.windows.net/<container>/<blob>
  • Delete Blob
DELETE https://<account>.blob.core.windows.net/<container>/<blob>

ADLS Gen2-Specific (Hierarchical Namespace enabled)🔗

  • Create Directory
PUT https://<account>.dfs.core.windows.net/<filesystem>/<directory>?resource=directory
  • Create File
PUT https://<account>.dfs.core.windows.net/<filesystem>/<directory>/<file>?resource=file
  • Append Data
PATCH https://<account>.dfs.core.windows.net/<filesystem>/<directory>/<file>?action=append&position=0
  • Flush Data (commit)
PATCH https://<account>.dfs.core.windows.net/<filesystem>/<directory>/<file>?action=flush&position=<length>

🔑 5. Versioning🔗

  • Each request must specify an API version in the x-ms-version header.
  • Example: x-ms-version: 2023-11-03
  • This ensures consistent behavior as Azure evolves.

🔑 6. Tools for Testing🔗

  • Postman / Insomnia → manually call REST APIs.
  • cURL for CLI-based requests.
  • AzCopy (built on REST API).
  • Azure Storage Explorer (GUI built on REST API).

✅ Summary: The Azure Storage REST API is the backbone of ADLS & Blob operations. You can:

  • Authenticate with Shared Key, SAS, or Azure AD.
  • Use Blob endpoints for standard blob storage.
  • Use DFS endpoints (.dfs.core.windows.net) for ADLS Gen2 hierarchical namespace features.
  • Issue standard HTTP verbs (GET, PUT, PATCH, DELETE) with required headers.

Python Example🔗

import requests
from azure.identity import ClientSecretCredential

# Azure AD app registration
tenant_id = "<tenant-id>"
client_id = "<client-id>"
client_secret = "<client-secret>"

# Authenticate
cred = ClientSecretCredential(tenant_id, client_id, client_secret)
token = cred.get_token("https://storage.azure.com/.default").token

# Storage details
account_name = "mystorageaccount"
filesystem = "mycontainer"
file_path = "demo_folder/test2.txt"
base_url = f"https://{account_name}.dfs.core.windows.net/{filesystem}/{file_path}"

# Create file
headers = {"Authorization": f"Bearer {token}", "x-ms-version": "2023-11-03"}
resp = requests.put(f"{base_url}?resource=file", headers=headers)
print("Create:", resp.status_code, resp.text)

# Append
data = b"Secure upload via Azure AD!"
resp = requests.patch(f"{base_url}?action=append&position=0",
                      headers={**headers, "Content-Length": str(len(data))},
                      data=data)
print("Append:", resp.status_code, resp.text)

# Flush
resp = requests.patch(f"{base_url}?action=flush&position={len(data)}",
                      headers={**headers, "Content-Length": "0"})
print("Flush:", resp.status_code, resp.text)