At transloadit we use
HAProxy “The Reliable, High Performance TCP/HTTP Load Balancer”
so that we can offer different services on 1 port.
For instance, depending on the hostname, a requests to port 80 can be routed to either
nodejs (in case of api.transloadit.com), or
nginx (in case of www.transloadit.com).
HAProxy has been good to us and setting it up was a breeze. But getting HAProxy to log on
Ubuntu Lucid was harder than I thought.
All of the tutorials I found either didn’t cover logging, or had deprecated information on it.
Google suddenly stopped being my friend.
HAProxy wants to log
For performance & maintenance reasons HAProxy doesn’t log directly to files. Instead it wants to log
against a syslog server. This is a separate Linux daemon that most servers are equiped with already,
but HAProxy requires it to listen on UDP port 514, and usually that’s not enabled.
A syslog server:
- receives log entries
- decides what’s interesting
- writes it to disk in a highly optimized way
these aspect can all be configured by you.
If we look at the top of your current
/etc/haproxy/haproxy.cfg file, we may find something like:
As you can see
127.0.0.1 is where it will try to find a syslog server to log to.
On Unbuntu Lucid the default syslog daemon is rsyslogd,
so let’s make it accept HAProxy log entries.
rsyslogd welcomes HAProxy
Most google hits I found on logging with HAProxy told me to change the
/etc/default/rsyslog file, but
that’s completely ignored with the new upstart system.
And even if you make it adhere the defaults file (yep, I tried), it will make
rsyslogd go down in compatibility mode. Which is not only a shame, but also
unnecessary as it turns out.
Using these config lines:
rsyslogd will open up it’s UDP port.
Where to put these lines you say? Well, if HAProxy is the only service you need the
UDP syslog port for, you could put/uncomment the lot in just
/etc/rsyslog.d/49-haproxy.conf file (Thanks to Gilles for the ‘49-’ prefix):
Now do a quick:
And you’re done. Check for HAProxy logs in:
Don’t forget to tweak the debug level in
/etc/haproxy/haproxy.cfg, and maybe set up
a logrotate right away in
These were imported from my old blog. Please use disqus below for new comments
on 2011-04-17 17:01:11
@ Steven Parkes &
amp; Paul Charles Leddy: Very good additions, thanks a lot guys.
Paul Charles Leddy
on 2011-03-21 22:26:59
Is that logrotate script pointing at the same logs defined in the haproxy.cfg you have sampled here?
on 2011-03-18 00:31:40
Suggest you add
so that you don’t open a port to the rest of the network.
on 2011-03-03 00:15:19
Thanks for the great article, this helped me setup logs in no time
on 2011-01-14 18:20:02
Wow that is really spooky. I haven’t posted that yet, but I was about to. What’s more, I can prove it:
How about that : )
on 2011-01-14 17:21:02
I’d add that I would setup logrotate along with those files and make sure it rotates at an appropriate rate and also only keeps files so and so long.
on 2010-11-10 02:26:25
yes! thank you so much! this is exactly what i needed.
on 2010-10-11 13:56:01
@ Dave Morehouse: You’re welcome : )
on 2010-10-04 21:24:10
Kevin - Thanks for the helpful tutorial. I needed to debug my HAProxy configuration and spent all day trying to get HAP logs to show up in syslog. Then I found your article and got it up and running in 5 minutes. This was a great tutorial for getting HAP logs working for those of us that aren’t familiar with syslogs.