Azure Blob Storage

Lightweight, dependency-free fake of Azure Blob Storage that speaks the real Azure Blob REST API (XML wire protocol + x-ms-* headers), so application code using @azure/storage-blob can run against it with zero cost and zero side effects.

Quick Start

Start the server:

import { AzureblobServer } from "./services/azureblob/src/server.js";

const server = new AzureblobServer(4590);
await server.start();
// ... use it ...
await server.stop();

Connect with the real Azure SDK client. The fake uses path-style addressing (like Azurite), so the blob endpoint always includes the account name:

import { BlobServiceClient, StorageSharedKeyCredential } from "@azure/storage-blob";

const account = "devstoreaccount1";
const key =
  "Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==";

const credential = new StorageSharedKeyCredential(account, key);
const svc = new BlobServiceClient(
  `http://127.0.0.1:4590/${account}`,
  credential,
);

const container = svc.getContainerClient("my-container");
await container.create();

const blob = container.getBlockBlobClient("hello.txt");
await blob.upload("hello parlel", 12);

const dl = await blob.download();
// dl.readableStreamBody -> "hello parlel"

You can also connect via a connection string:

const conn =
  "DefaultEndpointsProtocol=http;AccountName=devstoreaccount1;" +
  "AccountKey=Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==;" +
  "BlobEndpoint=http://127.0.0.1:4590/devstoreaccount1;";

const svc = BlobServiceClient.fromConnectionString(conn);

Note: the fake does not validate the Shared Key signature — any account name / key is accepted. The well-known Azurite dev account above is provided for convenience and copy-paste compatibility.

Addressing

URLs are path-style: http://127.0.0.1:4590/{account}/{container}/{blob}?{comp}=...

Implemented Operations

Service (BlobServiceClient)

Container (ContainerClient)

Blob (BlobClient)

Block Blob (BlockBlobClient)

uploadData, uploadStream, uploadFile, downloadToBuffer all work via the above (large uploads are automatically split into staged blocks by the SDK).

Append Blob (AppendBlobClient)

Page Blob (PageBlobClient)

Lease (BlobLeaseClient)

Acquire, Renew, Change, Release, Break — for both blobs and containers via comp=lease and the x-ms-lease-action header.

Batch (BlobBatchClient)

multipart/mixed sub-request batching at comp=batch:

• deleteBlobs(...) — batch Delete Blob
• setBlobsAccessTier(...) — batch Set Access Tier

Surface coverage

This emulator faithfully replicates the API surface most application code and agents exercise. Anything below the supported lines is either an intentional design choice for a fast, zero-cost local emulator (✓ By design) or a candidate for a future release (⟳ Roadmap) — never a silent inaccuracy.

Legend: ✅ fully supported · ◐ accepted (stored, not strictly enforced) · ✓ by design · ⟳ on the roadmap.

Error Codes & Shapes

Errors are returned as Azure-style XML with a matching x-ms-error-code response header:

<?xml version="1.0" encoding="utf-8"?>
<Error><Code>BlobNotFound</Code><Message>The specified blob does not exist.</Message></Error>

Health & Reset

Non-Azure internal endpoints for orchestration:

• GET /_parlel/health → { "status": "ok", "service": "azureblob", "containers": <n> }
• POST /_parlel/reset → { "ok": true } — clears all in-memory state.

Configuration — test.env

Copy these into your test.env (used by the bridge sidecar flow). Tokens are Parlel's seeded test credentials — any non-empty value is accepted by the emulator, so you rarely need to change them. Swap in real credentials only when pointing at the live service in prod.env.

AZURE_STORAGE_ACCOUNT=devstoreaccount1
AZURE_STORAGE_KEY=Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==
AZURE_STORAGE_CONNECTION_STRING=DefaultEndpointsProtocol=http;AccountName=devstoreaccount1;AccountKey=Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==;BlobEndpoint=http://127.0.0.1:4590/devstoreaccount1;