DSpace 7.6 - signposting links cause header limit issues with Apache

[Agustina Martinez-Garcia]

Hi all,

We are testing the upgrade to DSpace 7.6. We have Apache in front of dspace UI and have started seeing "bad gateway" errors when accessing items. This happens mostly with items with a large number of files (bitstreams) associated with them The example item we are using here has more 500 files. The errors we see in Apache logs are:

[Sat Jul 01 14:52:38.800373 2023] [proxy_http:warn] [pid 4123617] (28)No space left on device: [client 172.22.88.64:0] AH10124: header size is over the limit allowed by ResponseFieldSize (8192 bytes). Bad response header: 'Link: <https://dev-www.repository.cam.ac.uk/bitstreams/cbaf36e9-[...] ; rel="item" ; type="audio/mpeg" , <https://dev-www.repository.'

[Sat Jul 01 14:52:38.800435 2023] [proxy_http:warn] [pid 4123617] [client 172.22.88.64:0] AH01106: bad HTTP/1.1 header returned by /items/f5eff2ac-3208-4e90-96ee-14cd68e8d1ac (GET)

I have tried increasing the apache setting as per guidance: https://httpd.apache.org/docs/2.2/mod/core.html#limitrequestfieldsize but the issue still persists.

I can also confirm that when disabling signposting, the issue disappears.

Anyone experiencing the same behaviour?

[Agustina Martinez-Garcia]

Some updates:

It turns out that if using mod_proxy, the setting to change is responsefieldsize. It needs adding to the ProxyPass of the apache configuration, e.g. 

ProxyPass / http://localhost:4000/ responsefieldsize=12392

In case it helps others seeing the same issue. Increasing this to a very large number does not seem like a very secure option. Would it be possible for the signposting feature to include a configuration setting to limit the number of links added to the header?

Best,

Agustina 

[DSpace Technical Support]

Hi Agustina,

I'd recommend adding your feedback on signposting limiting the Links to a bug ticket in https://github.com/DSpace/DSpace/issues  That way I can find a volunteer to look into options.

In the meantime, I also wanted to note that it **is possible to turn Signposting off entirely** (if it's causing a headache right now).   See the "Enabling/Disabling" section here: https://wiki.lyrasis.org/display/DSDOC7x/Signposting

Signposting currently is *on* by default, but you are welcome to turn it off for now.  There is no major risk in doing so at this time, unless you require the Signposting feature for an integration with an external service.

Tim

[Agustina Martinez-Garcia]

Hi Tim,

Thanks for the suggestion - will open an issue then.

Agustina