multer-az-storage-blob
v1.0.2
Published
ES5/6 & Typescript friendly multer storage engine for Azure's blob storage using @azure/storage-blob.
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Multer Azure Blob Storage
ES6 & Typescript friendly Multer storage engine for Azure's blob storage.
Adapted from package multer-azure-blob-storage, updated to use a more recent blob storage dependency. All attempts were made to be backwards compatible, please report any issues if you switch to this package for existing code.
Installation
npm i -S multer-az-storage-blob
or
yarn add multer-az-storage-blob
Usage
Typescript
Leverages strong typings
import * as multer from 'multer';
import { MulterAzureStorage, MASNameResolver } from 'multer-az-storage-blob';
const resolveBlobName: MASNameResolver = (req: any, file: Express.Multer.File): Promise<string> => {
return new Promise<string>((resolve, reject) => {
const blobName: string = yourCustomLogic(req, file);
resolve(blobName);
});
};
export type MetadataObj = { [k: string]: string };
const resolveMetadata: MASObjectResolver = (req: any, file: Express.Multer.File): Promise<MetadataObj> => {
return new Promise<MetadataObj>((resolve, reject) => {
const metadata: MetadataObj = yourCustomLogic(req, file);
resolve(metadata);
});
};
const resolveContentSettings: MASObjectResolver = (req: any, file: Express.Multer.File): Promise<MetadataObj> => {
return new Promise<MetadataObj>((resolve, reject) => {
const contentSettings: MetadataObj = yourCustomLogic(req, file);
resolve(contentSettings);
});
};
const azureStorage: MulterAzureStorage = new MulterAzureStorage({
authenticationType: 'azure ad',
accountName: 'mystorageaccountname',
containerName: 'documents',
blobName: resolveBlobName,
metadata: resolveMetadata,
contentSettings: resolveContentSettings,
containerAccessLevel: 'blob',
});
const upload: multer.Instance = multer({
storage: azureStorage
});
app.post('/documents', upload.any(), (req: Request, res: Response, next: NextFunction) => {
console.log(req.files)
res.status(200).json(req.files)
});
Javascript ES6
Common.js style imports
const multer = require('multer')
const MulterAzureStorage = require('multer-az-storage-blob').MulterAzureStorage;
E6 style imports
import * as multer from 'multer';
import { MulterAzureStorage } from 'multer-az-storage-blob';
Rest of the JS code
const resolveBlobName = (req, file) => {
return new Promise((resolve, reject) => {
const blobName = yourCustomLogic(req, file);
resolve(blobName);
});
};
const resolveMetadata = (req, file) => {
return new Promise((resolve, reject) => {
const metadata = yourCustomLogic(req, file);
resolve(metadata);
});
};
const resolveContentSettings = (req, file) => {
return new Promise((resolve, reject)) => {
const contentSettings = yourCustomLogic(req, file);
resolve(contentSettings);
};
};
const azureStorage = new MulterAzureStorage({
authenticationType: 'azure ad',
accountName: 'mystorageaccountname',
containerName: 'documents',
blobName: resolveBlobName,
metadata: resolveMetadata,
contentSettings: resolveContentSettings,
containerAccessLevel: 'blob'
});
const upload = multer({
storage: azureStorage
});
app.post('/documents', upload.any(), (req, res, next) => {
console.log(req.files)
res.status(200).json(req.files)
});
More details on using upload
can be found in the Multer documentation
File information
Multer Azure Blob Storage will return the following information in each file uploaded. This can be found in the req.files
param:
Key | Description | Note
---|---|---
fieldname
| The field name/key sent in the form's post request. | Added by Multer
originalname
| Full original name of the file on the user's computer. | Added by Multer
encoding
| File encoding type. | Added by Multer
mimetype
| MIME type of the file. | Added by Multer
blobName
| Blob/file name of created blob in Azure storage. |
container
| Name of azure storage container where the blob/file was uploaded to. |
blobType
| Type of blob. | From the result of call to azure's getProperties()
of BlockBlobClient
size
| Size of the blob. | From the result of call to azure's getProperties()
of BlockBlobCClient
etag
| Etag. | From the result of call to azure's getProperties()
of BlockBlobCClient
metadata
| Blob's metadata. | From the result of call to azure's getProperties()
of BlockBlobClient
url
| The full url to access the uploaded blob/file. | obtained from 'BlockBlobClient'
Configuration object
Details of the configuration object that needs to be passed into the constructor of the MulterAzureStorage class. When dependency migrated from older azure blob package, all attempts were made to ensure backward compatibility for code using the alternate so many configuration variables are not required or can be passed via environment variables instead.
| Parameter Name | Type | Note | Sample Value |
|---|---|---|---|
| authenticationType
| string
(optional) | If not specified, will attempt to authenticate based on what auth info is provided.
|'azure ad'
or 'sas token'
or 'connection string'
or 'account name and key'
|
| sasToken
| string
| Can also be provided as env. variable AZURE_STORAGE_SAS_TOKEN
| sp=racwdl&st=2020-02-02T02:02:02Z&se=2020-02-02T02:12:02Z&spr=https&sv=2020-02-02&sr=c&sig=xxxxx
| connectionString
| string
| Can also be provided as env. variable AZURE_STORAGE_CONNECTION_STRING.
| 'DefaultEndpointsProtocol=https;AccountName=mystorageaccountname;AccountKey=wJalrXUtnFEMI/K7MDENG/bPxRfiCYzEXAMPLEKEY;EndpointSuffix=core.windows.net'
|
| accessKey
| string
| Can also be provided as env. variable AZURE_STORAGE_ACCESS_KEY
| 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYzEXAMPLEKEY'
|
| accountName
| string
| Can also be provided as env. variable AZURE_STORAGE_ACCOUNT
| 'mystorageaccountname'
|
| containerName
| string
or function: MASNameResolver
| | 'documents'
or (req: any, file: Express.Multer.File) => Promise<string>
|
| metadata
| { [k: string]: string }
or function: MASObjectResolver
| This metadata will be passed to Azure Blob Storage
|'{author: John Doe; album: ASOT}'
or (req: any, file: Express.Multer.File) => Promise<{[k: string]: string}>
|
| blobName
| function: MASNameResolver
(optional) | |(req: any, file: Express.Multer.File) => Promise<string>
|
| containerAccessLevel
| string
(optional) | | 'blob'
or 'container'
or 'private'
|
| urlExpirationTime
| number
(optional) | This field is now deprecated and unused, but remains in the signature for legacy code.
| 60
|
For more information about the meaning of individual parameters please check Azure documentation on node.js integration.
Defaults
For the optional parameters in the configuration object for the MulterAzureStorage class, here are the default fallbacks:
containerAccessLevel
: privateblobName
: Date.now() + '-' + uuid.v4() + path.extname(file.originalname). This results in a url safe filename that looks like'1511161727560-d83d24c8-d213-444c-ba72-316c7a858805.png'
urlExpirationTime
: used in a previous version of this package, it is retained for backwards compatibility, but no longer used.
File naming
The containerName
can be anything you choose, as long as it's unique to the storage account and as long as it fits Azure's naming restrictions. If the container does not exist the storage engine will create it.
The blobName
in an Azure container also needs to have a unique name.
multer-azure-storage-blob
allows you to customize the containerName
and blobName
per request before uploading the file. This can be done by proving a MASNameResolver
function in the configuation object for the desired parameter.
const resolveName: MASNameResolver = (req: any, file: Express.Multer.File): Promise<string> => {
return new Promise<string>((resolve, reject) => {
// Compute containerName or blobName with your custom logic.
const computedName: string = yourCustomLogic(req, file);
resolve(computedName);
});
};
multer-azure-storage-blob
also allows you to add/customize metadata
and contentSettings
per request before uploading the file. This can be done by proving a MASObjectResolver
function in the configuation object for the desired parameter.
export type MetadataObj = { [k: string]: string };
const resolveMetadata: MASObjectResolver = (req: any, file: Express.Multer.File): Promise<MetadataObj> => {
return new Promise<MetadataObj>((resolve, reject) => {
const metadata: MetadataObj = yourCustomLogic(req, file);
resolve(metadata);
});
};
Azure
Creating a storage account
For instructions on how to create a storage account, see the following Azure documentation.
Credentials (Quick tips)
azure ad
is Microsoft's recommended method, please check Azure Documentation for more details on how to configure the blob storage account.
If this is not an option, sas token
authorization allows more granular control of access to blob storage. SAS tokens can be generated through the Azure portal for storage accounts and can be restricted to containers.
A valid connection string can contain a SAS token or the account name/key.
For explicit account name and access key authentication, provide the account's access key available through the Azure portal, and the name of the storage account. This method is the least secure and allows clients unrestricted access to all containers on the storage account.
Never commit SAS tokens, connection strings, or access keys to version control.
For backward compatibility, if no authenticationType is provided, it will attempt to use a connection string or account name / access key.
MulterAzureStorage will preferentially use configuration options as passed in. If they are not passed in, it will check for them as environment variables with the keys below.
- For authentication with
azure ad
, See [additional documentation] (https://learn.microsoft.com/en-us/javascript/api/overview/azure/identity-readme?view=azure-node-latest#defaultazurecredential) on how to configure your application to securely use Azure AD for blob storage integration. In development you must include one of these sets of credential variables as environment variables or entries in .env file. - AZURE_STORAGE_CONNECTION_STRING, for the
connectionString
. - AZURE_STORAGE_ACCESS_KEY, for the
accessKey
. - AZURE_STORAGE_ACCOUNT, for the
accountName
. - AZURE_STORAGE_SAS_TOKEN, for the
sasToken
Tests
Not implemented yet
Thanks
All great things are built on the shoulder of giants. I want to thank my giants for lending their shoulders: