On Wed, 13 Aug 2014 14:22:28 -0400 Dave Shevett <[email protected]> wrote:
> Hi everyone. We have a set of load balanced back end appservers behind > haproxy. We're running pretty large amount of traffic and things have > been running great for the last 2 years or so. > > We'd like the ability to manually specify a back end server within a > cluster (this has to do with running a command to flush out the cache on > a specific server). > > Without manually altering the cookie in the browser to specify which > back end server to use, can we do something like add a string onto the > URL to specify which of the back end servers to use? > > For the following config, we normally hit http://stg.redacted.com, and > it sets the HASRVID cookie which it uses to specify the back end. Can > we do something like http://stg.redacted.com/?HASRVID=stg-2 to manually > select the back end? > > Here's the relevant sections of our config file: > > defaults > balance roundrobin > > frontend http_proxy > use_backend blahblah > > backend blahblah > mode http > option httpchk GET /magicurl > cookie HASRVID insert indirect nocache > > server stg-1 stg-1.REDACTED.com:80 cookie stg-1 check inter 10000 > rise 2 fall 5 > server stg-2 stg-2.REDACTED.com:80 cookie stg-2 check inter 10000 > rise 2 fall 5 > server stg-3 stg-3.REDACTED.com:80 cookie stg-3 check inter 10000 > rise 2 fall 5 Hi, You have many way to do this: - The first way is to force the cookie (with a cgi in an administration web server in the same domain) and use the directive "force-persist" (ACL). This directive permits to connect to the server even if it is administratively down. - The second way is to create one backend per server and use ACL. The acl check the "HASRVID" argument an frontend http_proxy use_backend stg1 if { urlp(HASRVID) stg-1 } use_backend stg2 if { urlp(HASRVID) stg-2 } use_backend stg3 if { urlp(HASRVID) stg-3 } d choose a backend if it is found. The configuration is like this (untested): frontend http_proxy use_backend stg1 if { urlp(HASRVID) stg-1 } use_backend stg2 if { urlp(HASRVID) stg-2 } use_backend stg3 if { urlp(HASRVID) stg-3 } default_backend blahblah backend stg1 server stg-1 stg-1.REDACTED.com:80 cookie stg-1 backend stg2 server stg-2 stg-2.REDACTED.com:80 cookie stg-2 backend stg3 server stg-3 stg-3.REDACTED.com:80 cookie stg-3 backend blahblah [...] - Other way is to force the cookie with haproxy using ACL. It is a mix between the two last way: backend blahblah acl admin src <your.ip> http-request redirect location / set-cookie HASRVID=stg-1 if { urlp(HASRVID) stg-1 } admin http-request redirect location / set-cookie HASRVID=stg-2 if { urlp(HASRVID) stg-2 } admin http-request redirect location / set-cookie HASRVID=stg-3 if { urlp(HASRVID) stg-3 } admin http-request redirect location / clear-cookie HASRVID if { urlp(HASRVID) clear } admin force-persist if admin [...] Thierry > Thanks! > > -d >
