HTTP error 100 shown when uploading large store paths

[flokli]

Moved from #17 (comment) (cc @ajs124)

warning: error: unable to upload 'http://[::1]:9000/nar/1yfga509smsrx1l8a4dnri551qy3kw0859w5gmc0j3vcxvwbdkvk.nar': HTTP error 100 ('Continue') (curl error: Server returned nothing (no headers, no data)); retrying in 253 ms
warning: error: unable to upload 'http://[::1]:9000/nar/1yfga509smsrx1l8a4dnri551qy3kw0859w5gmc0j3vcxvwbdkvk.nar': HTTP error 100 ('Continue') (curl error: Server returned nothing (no headers, no data)); retrying in 532 ms
warning: error: unable to upload 'http://[::1]:9000/nar/1yfga509smsrx1l8a4dnri551qy3kw0859w5gmc0j3vcxvwbdkvk.nar': HTTP error 100 ('Continue') (curl error: Server returned nothing (no headers, no data)); retrying in 1183 ms
warning: error: unable to upload 'http://[::1]:9000/nar/1yfga509smsrx1l8a4dnri551qy3kw0859w5gmc0j3vcxvwbdkvk.nar': HTTP error 100 ('Continue') (curl error: Server returned nothing (no headers, no data)); retrying in 2625 ms
error: while uploading to HTTP binary cache at 'http://[::1]:9000': error: unable to upload 'http://[::1]:9000/nar/1yfga509smsrx1l8a4dnri551qy3kw0859w5gmc0j3vcxvwbdkvk.nar': HTTP error 100 ('Continue') (curl error: Server returned nothing (no headers, no data))

That might be Nix starting the HTTP PUT, but then not sending any data (presumably as it's still busy assembling the .nar file), and nix-casync nagging the client to keep sending data.

I've seen these error messages before, but they disappeared after increasing some timeouts.

I'm not sure if there's much that can be done on the nix-casync side, or whether that needs to be fixed in Nix.

[dasJ]

I dug into this a bit. Looks like go respects the Expect header [1] [2] and libcurl (used by nix as a HTTP client) sends it by default.

[dasJ]

Maybe you can immediately do r.Header.Del("Expect")?

[flokli]

Maybe you can immediately do r.Header.Del("Expect")?

I'm not sure I can, from inside a individual handler - that's too late, and I can't edit the request before https://cs.opensource.google/go/go/+/refs/tags/go1.17.6:src/net/http/server.go;l=1904;drc=refs%2Ftags%2Fgo1.17.6 is run, no?

[dasJ]

Probably easiest to open a Nix issue about this. Saying to expect a 100 response while not being able to properly handle it sounds like a bug to me