A lightweight file upload input for Django and Amazon S3.
Django-S3File allows you to upload files directly AWS S3 effectively bypassing your application server. This allows you to avoid long running requests from large file uploads. This is particularly helpful for if you run your service on AWS Lambda or Heroku where you have a hard request limit.
- lightweight: less 200 lines
- no JavaScript or Python dependencies (no jQuery)
- easy integration
- works just like the built-in
- extendable JavaScript API
sequenceDiagram
autonumber
actor Browser
participant S3
participant Middleware
Browser->>Django: GET form view
activate Django
Django->>Browser: RESPONSE w/ presigned POST URL & signed middleware key
deactivate Django
Browser->>S3: POST large file
activate S3
S3->>Browser: RESPONSE AWS S3 key
Browser->>Middleware: POST AWS S3 key (signed)
activate Middleware
Middleware->>S3: GET AWS S3 key
S3->>Middleware: RESPONSE large file promise
deactivate S3
Middleware->>Django: request incl. large file promise
deactivate Middleware
activate Django
opt only if files is procssed by Django
Django-->>S3: GET large file
activate S3
S3-->>Django: RESPONSE large file
deactivate S3
end
Django->>Browser: RESPONSE success
deactivate Django
In a nutshell, we can bypass Django completely and have AWS handle the upload or any processing. Of course, if you want to do something with your file in Django, you can do so, just like before, with the added advantage, that your file is served from within your datacenter.
Make sure you have Amazon S3 storage setup correctly.
Just install S3file using pip.
pip install django-s3file
# or
pipenv install django-s3fileAdd the S3File app and middleware in your settings:
# settings.py
INSTALLED_APPS = (
'...',
's3file',
'...',
)
MIDDLEWARE = (
'...',
's3file.middleware.S3FileMiddleware',
'...',
)S3File automatically replaces Django's ClearableFileInput widget, you
do not need to alter your code at all.
The ClearableFileInput widget is only than automatically replaced when
the DEFAULT_FILE_STORAGE setting is set to django-storages'
S3Boto3Storage or the dummy FileSystemStorage is enabled.
S3File uploads to a single folder. Files are later moved by Django when
they are saved to the upload_to location.
It is recommended to setup expiration for that folder, to ensure that old and unused file uploads don't add up and produce costs.
The default folder name is: tmp/s3file You can change it by changing
the S3FILE_UPLOAD_PATH setting.
You will need to allow POST from all origins. Just add the following
to your CORS policy.
[
{
"AllowedHeaders": [
"*"
],
"AllowedMethods": [
"POST"
],
"AllowedOrigins": [
"*"
],
"ExposeHeaders": [],
"MaxAgeSeconds": 3000
}
]S3File does emit progress signals that can be used to display some kind
of progress bar. Signals named progress are emitted for both each
individual file input as well as for the form as a whole.
The progress signal carries the following details:
console.log(event.detail)
{
progress: 0.4725307607171312 // total upload progress of either a form or single input
loaded: 1048576 // total upload progress of either a form or single input
total: 2219064 // total bytes to upload
currentFile: File {…} // file object
currentFileName: "text.txt" // file name of the file currently uploaded
currentFileProgress: 0.47227834703299176 // upload progress of that file
originalEvent: ProgressEvent {…} // the original XHR onprogress event
}The following example implements a Boostrap progress bar for upload progress of an entire form.
<div class="progress">
<div class="progress-bar" role="progressbar" style="width: 0%;" aria-valuenow="0" aria-valuemin="0" aria-valuemax="100">0%</div>
</div>(function () {
var form = document.getElementsByTagName('form')[0]
var progressBar = document.getElementsByClassName('progress-bar')[0]
form.addEventListener('progress', function (event) {
// event.detail.progress is a value between 0 and 1
var percent = Math.round(event.detail.progress * 100)
progressBar.setAttribute('style', 'width:' + percent + '%')
progressBar.setAttribute('aria-valuenow', percent)
progressBar.innerText = percent + '%'
})
})()Using S3File in development can be helpful especially if you want to use
the progress signals described above. Therefore, S3File comes with a AWS
S3 dummy backend. It behaves similar to the real S3 storage backend. It
is automatically enabled, if the DEFAULT_FILE_STORAGE setting is set
to FileSystemStorage.
To prevent users from accidentally using the FileSystemStorage and the
insecure S3 dummy backend in production, there is also an additional
deployment check that will error if you run Django's deployment check
suite:
python manage.py check --deployWe recommend always running the deployment check suite as part of your deployment pipeline.
Django does have limited support for uploading multiple
files.
S3File fully supports this feature. The custom middleware makes ensure
that files are accessible via request.FILES, even though they have
been uploaded to AWS S3 directly and not to your Django application
server.
Since S3Boto3Storage supports storing data from any other fileobj, it
uses a generalized _save function. This leads to the frontend
uploading the file to S3 and then copying it byte-by-byte to perform a
move operation just to rename the uploaded object. For large files this
leads to additional loading times for the user.
That's why S3File provides an optimized version of this method at
storages_optimized.S3OptimizedUploadStorage. It uses the more
efficient copy method from S3, given that we know that we only copy
from one S3 location to another.
from s3file.storages_optimized import S3OptimizedUploadStorage
class MyStorage(S3OptimizedUploadStorage): # Subclass and use like any other storage
default_acl = 'private'