[Mongrel] Problems monitoring Mongrel with F5 BigIP

Brandorr brandorr at opensolaris.org
Fri Aug 10 21:17:40 EDT 2007

I think you need to close the connection after each health check.
Otherwise mongrel/rails is going to block. (If my understanding is

Try the following health check and let me know how it works out:

"GET / HTTP/1.1\nHost: \nConnection: Close\n

On 8/10/07, Christopher Bailey <chris at codeintensity.com> wrote:
> If this has already been covered, please point me to that (I didn't find
> anything in my searches)...
> We are using F5 BigIP LTM load balancers.  They have many pools of Mongrels
> they load balance across, and I of course want the F5 to know when a Mongrel
> goes down or is unavailable, etc.  To do that, I need to have an F5 health
> monitor for HTTP make a request to the Mongrel.  We do this same thing with
> our Nginx servers, and that works fine, but with Mongrel it doesn't.  I am
> wondering if anyone is successfully monitoring Mongrel instances from an F5?
> As further info...  I've been working with F5 tech support on this, and
> we're both stumped at the moment.  The same HTTP monitor works fine with
> Nginx.  Both try to fetch the same HTML file.  Also, if I am ssh'ed in to
> the F5, and do a telnet to one of the Mongrels and do "GET /heartbeat.html
> HTTP/1.1", followed by two returns, this works fine.  I use that same string
> (and two \n's) in my F5's send string for it's HTTP monitor.  According to
> F5 who looked at our tcpdump, the Mongrel just never responds (but in the
> same dump, they see the direct telnet version respond fine).  The F5 makes a
> direct TCP request to do this.
> Any ideas?  Suggestions?  Known issue?  Workarounds?  Anyone successful with
> this type of setup?
> As an FYI, our system info:
> CentOS 5, nearly all up to date, 64bit, Core 2 Duo processor
> Mongrel 1.0.1
> Mongrel Cluster 1.0.2
> Ruby 1.8.5 (2006-08-25) [x86_64-linux]
> F5 BigIP LTM, currently running 9.1.2 (working on moving to 9.3)
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