3 ms·

Trailers don't let you change the status code though.

• deleted 3y ago
  [deleted]
• acdha 3y ago
  That’s really the big one for me: can my server easily do something to cause e.g. curl to fail with a non-zero status or a JavaScript fetch to hit the error path? Satisfying that would make this approach easier to use safely.
  • vbezhenar 3y ago
    You can terminate connection before response body is fully served (assuming you have content-length or transfer-encoding chunked). curl will exit with error code in this case. Not sure about JS fetch. You can't carry any additional error codes or messages this way, though, just to signal that something's wrong. And you can't do anything if you already sent full response. And you would need access to sockets which might not be available in all HTTP libraries.
    • acdha 3y ago
      > You can terminate connection before response body is fully served (assuming you have content-length or transfer-encoding chunked). curl will exit with error code in this case. Those qualifiers were what I was thinking about - in most cases where this is relevant you don’t have the content length in advance, and transfer encoding chunked might not trigger this if the fault aligns with chunks or it’s being done by some middle layer.
      • vbezhenar 3y ago
        You need to send zero-length chunk to indicate end of stream. If you omit that chunk and close the connection, curl will fail.
        • acdha 3y ago
          Yes, but if you have middle layers doing that it might be done even in error states. I had that happen in multiple applications where it meant something like a big CSV file was successfully downloaded but incomplete (or, IIRC, had a Python traceback at the end). Having a simple, unambiguous way to force a failure reduces the odds of an error being easy to miss.