Azure Storage Blob Py

1---
2name: azure-storage-blob-py
3description: |
4  Azure Blob Storage SDK for Python. Use for uploading, downloading, listing blobs, managing containers, and blob lifecycle.
5  Triggers: "blob storage", "BlobServiceClient", "ContainerClient", "BlobClient", "upload blob", "download blob".
6package: azure-storage-blob
7---
8 
9# Azure Blob Storage SDK for Python
10 
11Client library for Azure Blob Storage — object storage for unstructured data.
12 
13## Installation
14 
15```bash
16pip install azure-storage-blob azure-identity
17```
18 
19## Environment Variables
20 
21```bash
22AZURE_STORAGE_ACCOUNT_NAME=<your-storage-account>
23# Or use full URL
24AZURE_STORAGE_ACCOUNT_URL=https://<account>.blob.core.windows.net
25```
26 
27## Authentication
28 
29```python
30from azure.identity import DefaultAzureCredential
31from azure.storage.blob import BlobServiceClient
32 
33credential = DefaultAzureCredential()
34account_url = "https://<account>.blob.core.windows.net"
35 
36blob_service_client = BlobServiceClient(account_url, credential=credential)
37```
38 
39## Client Hierarchy
40 
41| Client | Purpose | Get From |
42|--------|---------|----------|
43| `BlobServiceClient` | Account-level operations | Direct instantiation |
44| `ContainerClient` | Container operations | `blob_service_client.get_container_client()` |
45| `BlobClient` | Single blob operations | `container_client.get_blob_client()` |
46 
47## Core Workflow
48 
49### Create Container
50 
51```python
52container_client = blob_service_client.get_container_client("mycontainer")
53container_client.create_container()
54```
55 
56### Upload Blob
57 
58```python
59# From file path
60blob_client = blob_service_client.get_blob_client(
61    container="mycontainer",
62    blob="sample.txt"
63)
64 
65with open("./local-file.txt", "rb") as data:
66    blob_client.upload_blob(data, overwrite=True)
67 
68# From bytes/string
69blob_client.upload_blob(b"Hello, World!", overwrite=True)
70 
71# From stream
72import io
73stream = io.BytesIO(b"Stream content")
74blob_client.upload_blob(stream, overwrite=True)
75```
76 
77### Download Blob
78 
79```python
80blob_client = blob_service_client.get_blob_client(
81    container="mycontainer",
82    blob="sample.txt"
83)
84 
85# To file
86with open("./downloaded.txt", "wb") as file:
87    download_stream = blob_client.download_blob()
88    file.write(download_stream.readall())
89 
90# To memory
91download_stream = blob_client.download_blob()
92content = download_stream.readall()  # bytes
93 
94# Read into existing buffer
95stream = io.BytesIO()
96num_bytes = blob_client.download_blob().readinto(stream)
97```
98 
99### List Blobs
100 
101```python
102container_client = blob_service_client.get_container_client("mycontainer")
103 
104# List all blobs
105for blob in container_client.list_blobs():
106    print(f"{blob.name} - {blob.size} bytes")
107 
108# List with prefix (folder-like)
109for blob in container_client.list_blobs(name_starts_with="logs/"):
110    print(blob.name)
111 
112# Walk blob hierarchy (virtual directories)
113for item in container_client.walk_blobs(delimiter="/"):
114    if item.get("prefix"):
115        print(f"Directory: {item['prefix']}")
116    else:
117        print(f"Blob: {item.name}")
118```
119 
120### Delete Blob
121 
122```python
123blob_client.delete_blob()
124 
125# Delete with snapshots
126blob_client.delete_blob(delete_snapshots="include")
127```
128 
129## Performance Tuning
130 
131```python
132# Configure chunk sizes for large uploads/downloads
133blob_client = BlobClient(
134    account_url=account_url,
135    container_name="mycontainer",
136    blob_name="large-file.zip",
137    credential=credential,
138    max_block_size=4 * 1024 * 1024,  # 4 MiB blocks
139    max_single_put_size=64 * 1024 * 1024  # 64 MiB single upload limit
140)
141 
142# Parallel upload
143blob_client.upload_blob(data, max_concurrency=4)
144 
145# Parallel download
146download_stream = blob_client.download_blob(max_concurrency=4)
147```
148 
149## SAS Tokens
150 
151```python
152from datetime import datetime, timedelta, timezone
153from azure.storage.blob import generate_blob_sas, BlobSasPermissions
154 
155sas_token = generate_blob_sas(
156    account_name="<account>",
157    container_name="mycontainer",
158    blob_name="sample.txt",
159    account_key="<account-key>",  # Or use user delegation key
160    permission=BlobSasPermissions(read=True),
161    expiry=datetime.now(timezone.utc) + timedelta(hours=1)
162)
163 
164# Use SAS token
165blob_url = f"https://<account>.blob.core.windows.net/mycontainer/sample.txt?{sas_token}"
166```
167 
168## Blob Properties and Metadata
169 
170```python
171# Get properties
172properties = blob_client.get_blob_properties()
173print(f"Size: {properties.size}")
174print(f"Content-Type: {properties.content_settings.content_type}")
175print(f"Last modified: {properties.last_modified}")
176 
177# Set metadata
178blob_client.set_blob_metadata(metadata={"category": "logs", "year": "2024"})
179 
180# Set content type
181from azure.storage.blob import ContentSettings
182blob_client.set_http_headers(
183    content_settings=ContentSettings(content_type="application/json")
184)
185```
186 
187## Async Client
188 
189```python
190from azure.identity.aio import DefaultAzureCredential
191from azure.storage.blob.aio import BlobServiceClient
192 
193async def upload_async():
194    credential = DefaultAzureCredential()
195    
196    async with BlobServiceClient(account_url, credential=credential) as client:
197        blob_client = client.get_blob_client("mycontainer", "sample.txt")
198        
199        with open("./file.txt", "rb") as data:
200            await blob_client.upload_blob(data, overwrite=True)
201 
202# Download async
203async def download_async():
204    async with BlobServiceClient(account_url, credential=credential) as client:
205        blob_client = client.get_blob_client("mycontainer", "sample.txt")
206        
207        stream = await blob_client.download_blob()
208        data = await stream.readall()
209```
210 
211## Best Practices
212 
2131. **Use DefaultAzureCredential** instead of connection strings
2142. **Use context managers** for async clients
2153. **Set `overwrite=True`** explicitly when re-uploading
2164. **Use `max_concurrency`** for large file transfers
2175. **Prefer `readinto()`** over `readall()` for memory efficiency
2186. **Use `walk_blobs()`** for hierarchical listing
2197. **Set appropriate content types** for web-served blobs
220