Ha, I went to see if we could add a more helpful answer there and I see I’ve been there before. The question’s author selected the incorrect answer as most helpful to them. Content-Length is not a core attribute and would only exist in a scenario where a previous processor populated it. 

Andy LoPresto
PGP Fingerprint: 70EC B3E5 98A6 5A3F D3C4  BACE 3C6E F65B 2F7D EF69

On May 17, 2019, at 10:29 AM, Mike Thomsen <mikerthomsen@gmail.com> wrote:

Thanks, Mark

On Fri, May 17, 2019 at 1:29 PM Mark Payne <markap14@hotmail.com> wrote:

You can reference ${fileSize}. This is the size of a FlowFile in bytes.


On May 17, 2019, at 1:27 PM, Mike Thomsen <mikerthomsen@gmail.com> wrote:

Is there a way to get access to the flowfile size from EL? This said to use Content-Length, but that didn't appear to work for me on 1.8.0.