How to generate presigned S3 urls using django-storages?

Question

I have a Django form which saves a file to s3 through the django-storages library and works fine. How can I generate and return a pre-signed url so the user can access the file temporarily after it is uploaded ? Is this abstracted by django-storages or do I have to use the boto3 api?

I have spent hours going through the Django-storages documentation however it is not very clear how to do this ..

form.py

class DocumentForm(forms.Form):
    docfile = forms.FileField(
        label='Select a file',
        help_text='max. 42 megabytes'
    )
   name = models.CharField(max_length=20)
   uploaded_at = models.DateTimeField(auto_now_add=True)

views.py

def upload_file(request):
   if request.method == 'POST:
      form = DocumentForm(request.POST)
      if form.is_valid():
         form.save()
         url = #generate pre-signed url of uploaded file here
         return render(request, 'upload_response.html', url)

Tamdim · Accepted Answer · 2021-03-25T12:30:38.360

9

Turns out you do not need to use boto3 to generate a presigned url. Django-storages abstracts the entire process. You can simply generate it as follows docfile.url.

--- Edit ----

For reference, here is the S3 storage class method that generates the pre-signed url for you https://github.com/jschneier/django-storages/blob/770332b598712da27ecdba75c9e202ad6a1a8722/storages/backends/s3boto3.py#L554

edited Mar 25 '21 at 12:30

answered Feb 18 '21 at 16:30

Tamdim

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Can we get a reference to source on this? – coler-j Mar 25 '21 at 12:10
1

I have just edited the answer with a link to the reference – Tamdim Mar 25 '21 at 12:31
To actually return a URL with signature, make sure `AWS_QUERYSTRING_AUTH = True`. – webjunkie Oct 28 '22 at 11:26
Good point. I believe it is set to True by default if not explicitly set in settings.py – Tamdim Oct 30 '22 at 23:40

score 2 · Answer 2 · answered Oct 09 '20 at 16:56

Here is sample code for generating pre-signed url for object in S3

import boto3

client = boto3.client('s3')
response = client.generate_presigned_url('get_object',Params={'Bucket': bucket_name,
                                                              'Key': objectpath},
                                         HttpMethod="GET", ExpiresIn=expires_in)

How to generate presigned S3 urls using django-storages?

2 Answers2

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