Altering responses

From reading the manual, I’m pretty sure this isn’t possible but thought I’d double check…

Is it possible to alter the HTTP content (not headers)? Specifically to inject some HTML into the start of the body?

No, its not possible out of the box.

Not sure if that’s you, but there is a discussion about this on the ML:

No, that wasn’t me. Shame it isn’t possible, it would obviously have a significant performance impact, but there are situations it would be very useful. In my case, I want to inject some JavaScript to pop up a message warning visitors the website will shortly be unavailable. It’s easier to centralise this in one place, than need to do it across lots of separate back end applications.

Its not only performance impacting but also dangerous: