Resumable Uploads
Learn how to upload files to Supabase Storage.
The resumable upload method is recommended when:
- Uploading large files that may exceed 6MB in size
- Network stability is a concern
- You want to have progress events for your uploads
Supabase Storage implements the TUS protocol to enable resumable uploads. TUS stands for The Upload Server and is an open protocol for supporting resumable uploads. The protocol allows the upload process to be resumed from where it left off in case of interruptions. This method can be implemented using the tus-js-client library, or other client-side libraries like Uppy-js that support the TUS protocol.
Here's an example of how to upload a file using tus-js-client:
_51const tus = require('tus-js-client')_51_51const projectId = ''_51_51async function uploadFile(bucketName, fileName, file) {_51 const { data: session } = await supabase.auth.session()_51_51 return new Promise((resolve, reject) => {_51 var upload = new tus.Upload(file, {_51 endpoint: `https://${projectId}.supabase.co/storage/v1/upload/resumable`,_51 retryDelays: [0, 3000, 5000, 10000, 20000],_51 headers: {_51 authorization: `Bearer ${session.access_token}`,_51 'x-upsert': 'true', // optionally set upsert to true to overwrite existing files_51 },_51 uploadDataDuringCreation: true,_51 removeFingerprintOnSuccess: true, // Important if you want to allow re-uploading the same file https://github.com/tus/tus-js-client/blob/main/docs/api.md#removefingerprintonsuccess_51 metadata: {_51 bucketName: bucketName,_51 objectName: fileName,_51 contentType: 'image/png',_51 cacheControl: 3600,_51 },_51 chunkSize: 6 * 1024 * 1024, // NOTE: it must be set to 6MB (for now) do not change it_51 onError: function (error) {_51 console.log('Failed because: ' + error)_51 reject(error)_51 },_51 onProgress: function (bytesUploaded, bytesTotal) {_51 var percentage = ((bytesUploaded / bytesTotal) * 100).toFixed(2)_51 console.log(bytesUploaded, bytesTotal, percentage + '%')_51 },_51 onSuccess: function () {_51 console.log('Download %s from %s', upload.file.name, upload.url)_51 resolve()_51 },_51 })_51_51_51 // Check if there are any previous uploads to continue._51 return upload.findPreviousUploads().then(function (previousUploads) {_51 // Found previous uploads so we select the first one._51 if (previousUploads.length) {_51 upload.resumeFromPreviousUpload(previousUploads[0])_51 }_51_51 // Start the upload_51 upload.start()_51 })_51 })_51}
Upload URL
When uploading using the resumable upload endpoint, the storage server creates a unique URL for each upload, even for multiple uploads to the same path. All chunks will be uploaded to this URL using the PATCH method.
This unique upload URL will be valid for up to 24 hours. If the upload is not completed within 24 hours, the URL will expire and you'll need to start the upload again. TUS client libraries typically create a new URL if the previous one expires.
Concurrency
When two or more clients upload to the same upload URL only one of them will succeed. The other clients will receive a 409 Conflict error. Only 1 client can upload to the same upload URL at a time which prevents data corruption.
When two or more clients upload a file to the same path using different upload URLs, the first client to complete the upload will succeed and the other clients will receive a 409 Conflict error.
If you provide the x-upsert header the last client to complete the upload will succeed instead.
UppyJS example
You can check a full example using UppyJS.
UppyJS has integrations with different frameworks:
Overwriting files
When uploading a file to a path that already exists, the default behavior is to return a 400 Asset Already Exists error.
If you want to overwrite a file on a specific path you can set the x-upsert header to true.
We do advise against overwriting files when possible, as the CDN will take some time to propagate the changes to all the edge nodes leading to stale content. Uploading a file to a new path is the recommended way to avoid propagation delays and stale content.
To learn more, see the CDN guide.