Blobstore downloads have unknown size now that the Content-Length header is disallowed [35888819]

Bug

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Description

co...@gmail.com

created issue #1

Dec 27, 2010 02:40AM

According to the "Disallowed HTTP Response Headers" section in the Python Response class documentation here:

http://code.google.com/appengine/docs/python/tools/webapp/responseclass.html#Disallowed_HTTP_Response_Headers

the Content-Length header can no longer be set for "security purposes." Without being able to set that header, though, all blob downloads now have unknown lengths, causing all major browsers show unknown length progress indicators. This is an extremely undesirable state of affairs for the large and lengthy downloads which my app provides.

To solve this problem previously, I used the size field of the BlobInfo records in the datastore to set the Content-Length header directly, but now that this is no longer allowed, I am without recourse.

The following bug is related, but is not a solution to this problem:

http://code.google.com/p/googleappengine/issues/detail?id=2719&q=content-length&colspec=ID%20Type%20Component%20Status%20Stars%20Summary%20Language%20Priority%20Owner%20Log

Comments

ni...@google.com <ni...@google.com> Jan 19, 2011 11:42PM

Assigned to ni...@google.com.

[Deleted User] <[Deleted User]> #3Sep 22, 2011 01:49PM

[Comment deleted]

ej...@evanjones.ca <ej...@evanjones.ca> #4Oct 1, 2011 08:32PM

Interestingly: If the web client makes a byte range request, and the app allows this (use_ranges=True), then the server will report the correct output in the Content-Range header. For example, if you use:

touch (my_filename)
wget --server-response --continue (my blobstore URL)

Then wget will correctly show a progress bar for this request.

pe...@pepto.de <pe...@pepto.de> #7Apr 30, 2013 02:21PM

Even though "transfer-encoding: chunked" may be a perfectly legitimate way of transferring responses over HTTP, end-users will keep wondering why downloads from "your platform" don't have progress bars like anybody else.

I think it's really frustrating that Google just isn't fixing this... :-(

[Deleted User] <[Deleted User]> #8May 6, 2013 06:03PM

Another way to work around this is to perform a HEAD request and use that content-length. Assuming the content-length doesn't change between the requests.

jj...@gmail.com <jj...@gmail.com> #9Mar 25, 2014 01:27PM

[Comment deleted]

sr...@gmail.com <sr...@gmail.com> #10Aug 15, 2015 12:32PM

No fix for this even after 5 years?
This seems to be most stared issue regarding BlobStore.
I'm facing this problem in Java

ni...@daskalou.com <ni...@daskalou.com> #13Jan 30, 2017 02:43AM

We are experiencing this same issue when serving objects stored in Google Cloud Storage (not Blobstore) using the X-AppEngine-BlobKey header.

is...@google.com <is...@google.com> May 11, 2018 07:44PM

Status: New