Espen Hovlandsdal
Written by Espen Hovlandsdal
Published 2014-01-13

Varnish + requests with no Content-Length header

HTTP 1.1 introduced the concept of chunked transfer encoding. This (among other things) enables us to send a request without knowing how large the content is going to be at the time we start the request.

An example usage would be where you generate content on-the-fly. You could potentially send chunks of a video-stream while you are recording or dynamically alter (compress, parse or similar) content from one source and incrementally send chunks to the server.

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In node.js, if you send an HTTP request without a Content-Length header, node will automatically add Transfer-Encoding: chunked to the list of headers, as well as automatically split your data into chunks.

Varnish does not currently treat requests without a Content-Length header very well. It adds a Content-Length header with a value of 0 and sends it to your backend without any data, which isn’t what we want. To fix this, you can add a simple check in your VCL to instead pipe the request directly to your backend:

Note: The way Varnish handles chunked transfer encoding might change in the future.

Enjoy streaming!

Written by Espen Hovlandsdal
Published 2014-01-13