On Wed, 2 Sep 2015 10:55:21 -0400
Michael Ezzell <[email protected]> wrote:
> You are NOT able to reproduce? I misunderstood your previous comment.
Yes I not reproduce.
> Further testing suggests (to me) that this is a timing issue, where HAProxy
> does not discover that the connection is established, if connection
> establishment doesn't happen within a very, very short window after the
> connection is attempted.
>
> Previously, I only tested "client talks first" (http) using a different
> machine as the server.
>
> Consider the following new results:
>
> server talks first (ssh) - connection to local machine - *works*
> server talks first (ssh) - connection to a different machine on same LAN -
> *works*
> server talks first (ssh) - connection to a different machine across
> Internet - *works*
> client talks first (http) - connection to local machine - *works*
> client talks first (http) - connection to a different machine on same
> LAN - *does
> not work*
> client talks first (http) - connection to a different machine across
> Internet - *does not work*
>
> The difference here seems to be the timing of the connection establishment,
> and the presence or absence of additional events. (Note that when I say
> "local machine" I do not mean 127.0.0.1; I am still using the local
> machine's Ethernet IP when talking to services on the local machine.)
>
> When you are testing, are you using a remote machine, so that there is a
> brief delay in connection establishment? If not, this may explain why you
> do not see the same behavior, since local connections do not appear to have
> the same problem.
Thank you for your investigation. It make sense. I use always my own
dev omputer for the functionnal tests. I will try to add some latency
in the network. And I hope to reproduce your problem.
> Most interesting, based on my "timing" theory, I found a workaround, which
> seems very wrong in principle; so wrong, in fact, that I can't believe I
> tried it; however, using the following tactic, I am able to make an
> outgoing socket connection to a different machine, when client talks first.
>
> local sock = core.tcp();
> sock:settimeout(3);
> local written = sock:send("GET
> /latest/meta-data/placement/availability-zone HTTP/1.0\r\nHost:
> 169.254.169.254\r\n\r\n");
> local connected, con_err = sock:connect("169.254.169.254",80);
> ...
>
> This strange code works. I hope you will agree that writing to the socket
> before connecting seems very wrong, and I was surprised to find that this
> code works successfully when connecting to a different machine --
> presumably because I'm pre-loading the outbound buffer, so the server's
> response to my request actually triggers an event that does not occur in a
> condition where the client talks first and when there is a delay in
> connection establishment, even a very brief delay.
I agree, its ugly :) but I understand why its runnings. When the
connection is established, the send buffer is filled, so HAProxy
automatically send its data. In this case it is useless to wakeup the
lua process when the connection is established. When the response data
are receive the process run perfectly.
The patch that you have talk about (BUG/MEDIUM: lua: outgoing
connection was broken since 1.6-dev2) doesn't fix correctly the bug :)
I look for this
Thierry
