HEAD no longer works in 5.4.1

Elastic Stack Elasticsearch
1

Hi all,

Not sure if this is intended behavior, but I've noticed HEAD no longer works since upgrading to 5.4.1. For example, on my 5.3.2 instance, this works:

curl -XHEAD -s -o /dev/null -w %{http_code} localhost:9200/.kibana

On 5.4.1 this just hangs. There's no security on the 5.4.1 instance.

I did a test from an external server so I could grab a tcpdump just in case it helps:

This hangs:

08:49:48.392897 IP source_server.42320 > ES-5.4.1.wap-wsp: Flags [S], seq 4061483896, win 29200, options [mss 1379,sackOK,TS val 1854819303 ecr 0,nop,wscale 7], length 0
08:49:48.392938 IP ES-5.4.1.wap-wsp > source_server.42320: Flags [S.], seq 1670349589, ack 4061483897, win 26847, options [mss 8961,sackOK,TS val 1921447501 ecr 1854819303,nop,wscale 7], length 0
08:49:48.417434 IP source_server.42320 > ES-5.4.1.wap-wsp: Flags [.], ack 1, win 229, options [nop,nop,TS val 1854819327 ecr 1921447501], length 0
08:49:48.417551 IP source_server.42320 > ES-5.4.1.wap-wsp: Flags [P.], seq 1:95, ack 1, win 229, options [nop,nop,TS val 1854819327 ecr 1921447501], length 94
08:49:48.417570 IP ES-5.4.1.wap-wsp > source_server.42320: Flags [.], ack 95, win 210, options [nop,nop,TS val 1921447526 ecr 1854819327], length 0
08:49:48.418932 IP ES-5.4.1.wap-wsp > source_server.42320: Flags [P.], seq 1:89, ack 95, win 210, options [nop,nop,TS val 1921447527 ecr 1854819327], length 88
08:49:48.445049 IP source_server.42320 > ES-5.4.1.wap-wsp: Flags [.], ack 89, win 229, options [nop,nop,TS val 1854819354 ecr 1921447527], length 0

This works:

08:45:24.203015 IP source_server.41862 > ES-5.3.2.wap-wsp: Flags [S], seq 3887748958, win 29200, options [mss 1379,sackOK,TS val 1854390542 ecr 0,nop,wscale 7], length 0
08:45:24.203087 IP ES-5.3.2.wap-wsp > source_server.41862: Flags [S.], seq 41657394, ack 3887748959, win 26847, options [mss 8961,sackOK,TS val 3541047347 ecr 1854390542,nop,wscale 7], length 0
08:45:24.265286 IP source_server.41862 > ES-5.3.2.wap-wsp: Flags [.], ack 1, win 229, options [nop,nop,TS val 1854390604 ecr 3541047347], length 0
08:45:24.265333 IP source_server.41862 > ES-5.3.2.wap-wsp: Flags [P.], seq 1:95, ack 1, win 229, options [nop,nop,TS val 1854390604 ecr 3541047347], length 94
08:45:24.265347 IP ES-5.3.2.wap-wsp > source_server.41862: Flags [.], ack 95, win 210, options [nop,nop,TS val 3541047409 ecr 1854390604], length 0
08:45:24.267156 IP ES-5.3.2.wap-wsp > source_server.41862: Flags [P.], seq 1:80, ack 95, win 210, options [nop,nop,TS val 3541047411 ecr 1854390604], length 79
08:45:24.307676 IP source_server.41862 > ES-5.3.2.wap-wsp: Flags [.], ack 80, win 229, options [nop,nop,TS val 1854390647 ecr 3541047411], length 0
08:45:24.307786 IP source_server.41862 > ES-5.3.2.wap-wsp: Flags [F.], seq 95, ack 80, win 229, options [nop,nop,TS val 1854390647 ecr 3541047411], length 0
08:45:24.307864 IP ES-5.3.2.wap-wsp > source_server.41862: Flags [F.], seq 80, ack 96, win 210, options [nop,nop,TS val 3541047452 ecr 1854390647], length 0
08:45:24.364514 IP source_server.41862 > ES-5.3.2.wap-wsp: Flags [.], ack 81, win 229, options [nop,nop,TS val 1854390703 ecr 3541047452], length 0
2

Hey,

I remember issues with curl and -X HEAD and connection keep alive when I played with it.. can you try --head instead?

Can you also explain what you mean with "this works" - where is the difference between those two requests when you issued them?

Thanks!

--Alex

3

Aha! That works! Thank you.

By works, I mean that it returns 200 whereas before it would just hang and return nothing. The first block was to a 5.4.1 instance, the second to 5.3.2. I'll update my scripts to use curl --head

Edit: looking back at the release notes, it seems there were changes to the way HEAD requests are handled which may explain the difference from 5.3.2 > 5.4.1

4

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