storage.ts

"use strict";

import { BlobServiceClient } from "@azure/storage-blob";
import "dotenv/config"

// This function creates client and perfroms authentication
async function getBlobServiceClient(): Promise<BlobServiceClient> {
  console.log("\nAuthenticating credentials for Azure Storage Account and creating a service client");

  const AZURE_STORAGE_CONNECTION_STRING =
    process.env.AZURE_STORAGE_CONNECTION_STRING;
  if (!AZURE_STORAGE_CONNECTION_STRING) {
    throw Error('Azure Storage Connection string not found');
  }
  // Create the BlobServiceClient object with connection string
  const blobServiceClient = BlobServiceClient.fromConnectionString(
    AZURE_STORAGE_CONNECTION_STRING
  );
  return blobServiceClient
}

// Function to conver steam into a buffer
// This buffer is converted to string and pinted
async function streamToBuffer(stream: NodeJS.ReadableStream): Promise<Buffer> {
  return new Promise((resolve, reject) => {
    const chunks: Buffer[] = [];
    stream.on("data", (data) => {
      chunks.push(Buffer.isBuffer(data) ? data : Buffer.from(data));
    });
    stream.on("end", () => {
      resolve(Buffer.concat(chunks));
    });
    stream.on("error", reject);
  });
}

async function getBlobDataAsString(blobName: string): Promise<void> {
  const blobServiceClient = await getBlobServiceClient();

  console.log("\nBlob Content");
  const CONTAINER_NAME = process.env.CONTAINER_NAME;
  if (!CONTAINER_NAME) {
    throw Error('Azure Storage Container name not found');
  }
  const containerClient = blobServiceClient.getContainerClient(CONTAINER_NAME);

  let blockBlobClient = containerClient.getBlockBlobClient(blobName);
  const downloadBlockBlobResponse = await blockBlobClient.download();
  console.log(
    `Downloaded blob content: \n ${(
      await streamToBuffer(downloadBlockBlobResponse.readableStreamBody!)
    ).toString()},`
  );
  console.log(
    `requestId - ${downloadBlockBlobResponse.requestId}, statusCode - ${downloadBlockBlobResponse._response.status}\n`
  );
}


async function listBlobsInContainer(): Promise<void> {
  console.log("\nList of Blobs");
  //TODO: Print the list blobs which are present in Azure storage container
  // Container name can be accessed from the env
  const CONTAINER_NAME = process.env.CONTAINER_NAME;
  if (!CONTAINER_NAME) {
      throw Error('Azure Storage Container name not found');
  }

}

getBlobDataAsString("2022-12-22-09-00.txt");
// listBlobsInContainer();