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Blob Storage

Compatible with the azure-storage-blob SDKs (Java, Python, Node.js), the Azure CLI (az storage blob), and Azurite-style connection strings. Speaks the Azure Storage Blob REST protocol with Shared Key authentication and XML responses.

HTTP-only — no Docker. Data is held by the configured storage backend (memory by default; persistent, hybrid, or wal for durability).

Features

  • Containers — Create, Get properties, Delete, List (?comp=list); duplicate create returns 409 ContainerAlreadyExists
  • Blobs — Put (upload), Get (download), Delete, List within a container; overwrite semantics
  • Block blobs — staged block upload (?comp=block) followed by commit (?comp=blocklist) for large payloads, in addition to single-request Put Blob
  • Range download — Range: bytes=… returns 206 Partial Content
  • Conditional download — If-Match / If-None-Match honored; a stale ETag is rejected
  • Metadata — x-ms-meta-* set on upload and returned on Get, round-tripped exactly
  • Not-found semantics — missing blob/container returns the Azure 404 BlobNotFound / ContainerNotFound XML error shape

Endpoint

http://localhost:4577/{account}/{container}                  # container operations
http://localhost:4577/{account}/{container}/{blob}           # blob operations

The account also answers at the host-style address {account}.blob.core.windows.net (and the Data Lake Gen2 alias {account}.dfs.core.windows.net, which maps to the same blob backend) when the Host header is set, matching how the SDKs address storage endpoints.

Quickstart

from azure.storage.blob import BlobServiceClient

conn = ("DefaultEndpointsProtocol=http;AccountName=devstoreaccount1;"
        "AccountKey=Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMh0==;"
        "BlobEndpoint=http://localhost:4577/devstoreaccount1;")
svc = BlobServiceClient.from_connection_string(conn)
container = svc.create_container("my-container")
container.upload_blob("hello.txt", b"hello world")
print(container.download_blob("hello.txt").readall())

az storage container create --name my-container \
  --connection-string "DefaultEndpointsProtocol=http;AccountName=devstoreaccount1;AccountKey=...;BlobEndpoint=http://localhost:4577/devstoreaccount1;"

The well-known Azurite development key (Eby8vdM0…) is accepted; any account name works.

Configuration

floci-az:
  services:
    blob:
      enabled: true
  storage:
    services:
      blob:
        # mode: wal            # override the global storage.mode for blob only
        flush-interval-ms: 5000
Property Env var Default Description
enabled FLOCI_AZ_SERVICES_BLOB_ENABLED true Enables the Blob Storage service
storage.services.blob.mode FLOCI_AZ_STORAGE_SERVICES_BLOB_MODE (inherits storage.mode) Per-service backend override (memory / persistent / hybrid / wal)
storage.services.blob.flush-interval-ms FLOCI_AZ_STORAGE_SERVICES_BLOB_FLUSH_INTERVAL_MS 5000 Background flush-to-disk interval for the hybrid mode only; ignored by memory / persistent / wal (wal compacts on storage.wal.compaction-interval-ms instead)

Intentional deviations

  • Shared Key signatures are accepted but not cryptographically verified — the emulator is a local dev target; any well-formed Authorization header (or the Azurite key) is honored.
  • No SAS enforcement — SAS query parameters are parsed but not validated.
  • Snapshots, versioning, leases, and tiering are not modeled.