On 25/01/2019 02:17, James H. H. Lampert wrote: > We have an application that runs on clustered Tomcat 8 servers, in three > sub-clusters (Google Managed Instance Groups, with nodes running under > Debian Stretch), all tied to a common load balancer. Each sub-cluster > runs a different webapp. > > To get to the sub-cluster running the main entry point, you would go to > https://frobozz.example. To get to the one running the report processor, > you would go to https://frobozz.example/reports. To get to the one > running the auxiliary processor, you would go to > https://frobozz.example/aux. The load balancer then routes the requests > to the proper sub-cluster. > > Because of the way things work with the load balancer, it expects to > find the main entry point as the ROOT context of the main sub-cluster, > and expects to find the other two as the "reports" context of the report > cluster, and the "aux" context of the auxiliary cluster. There may be a > way to configure the load balancer look for the root contexts on the > report and auxiliary clusters, but if so, I haven't found it.
Some load-balancers can do this but any configuration where you change the path between the reverse proxy and the back-end tends to create a whole bunch of subtle and not so subtle issues. Generally: http://loadbalancer/foo -> [http|ajp]://instanceN.tomcat/foo GOOD http://loadbalancer/foo -> [http|ajp]://foo.instanceN.tomcat BAD BAD is perhaps an overstatement. You can get it to work but it is a lot of work. I'd stick with the configuration you have., It is a lot less hassle. > When I've tried to run Tomcat without a ROOT context, it fails to > launch. What is the error message? A clean Tomcat install starts for me with no ROOT context (as I would expect). > And so, for the report and auxiliary clusters, the actual > webapps are on their ROOT contexts, and the named contexts are links in > the file system, pointing to the respective ROOT contexts. (I tried it > the other way around, and it behaved exactly the same as if I'd had no > ROOT context at all.) You'll likely end up with double deployment in that case. > Am I missing something? Something is going on but I'm not sure what. If something insists on there being a ROOT web application, I'd just create an empty ROOT directory in $CATALINA_BASE/webapps as a work-around until whatever was (incorrectly) requiring a ROOT webapp was fixed and deploy the apps to /aux and /reports as appropriate. If 'something' requires more than just an empty webapp then it is more complicated but, arguably, 'something' is more broken. Mark --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
