jxxcarlson
Presigned URLs with ExAws
Hello! I am using ExAws and the code below to make a presigned request for uploading image files to Amazon S3. All is well except that the permissions on the uploaded file are not being set to public-read:
def make_presigned_url(bucket, path, mime_type) do
query_params = [{"ContentType", mime_type}, {"ACL", "public-read"}]
presign_options = [query_params: query_params]
{:ok, presigned_url} = ExAws.Config.new(:s3)
|> ExAws.S3.presigned_url(:put, bucket, path, presign_options)
presigned_url
end
Do you see any other mistakes?
PS. Here is .typical presigned url produced with the above:
https://s3.amazonaws.com/noteimages/jxxcarlson/carr_fire_2.jpg?ACL=public-read&ContentType=image%2Fjpeg&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAJQYJYCIAWH6DGHIQ%2F20180809%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20180809T045031Z&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=e6e620f563606cfea26340c0f8f402bad35a5c50a841b25d5168bccf52f6da15Marked As Solved
wmnnd
I think this might simply not be possible. If you take a look at the AWS Java SDK docs, you can see that only a handful of parameters that would usually be sent as headers are supported (there is setContentMd5, setContentType, etc - but not setACL).
Also check out this GitHub issue with two possible workarounds.
Also Liked
tajchumber
I got it to work, it was very simple in the end!
here’s the code
ExAws.Config.new(:s3)
|> ExAws.S3.presigned_url(
:get,
bucked_name,
filename
)
wmnnd
ngocling_ng
Change your query_params to this:
query_params = [
{"ContentType", type},
{"x-amz-acl", "public-read"}
]
PJUllrich
I managed to generate a S3 presigned download URL which behaves like a file download by setting the response-content-disposition: "attachment" header:
config = ExAws.Config.new(:s3, region: get_region())
opts = [query_params: [{"response-content-disposition", "attachment; filename=#{file.filename}"}]]
{:ok, url} = ExAws.S3.presigned_url(config, :get, get_bucket(), file_path, opts)
If you redirect the user to this URL in your controller, it will automatically download and rename the file to file.filename.
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