Clearly one webapp per tomcat. Makes everything easier. Also, if your apps aren't really tiny, the memory overhead of tomcat is minimal compared to the advantages.
Leon On Mon, Oct 29, 2018 at 9:00 AM Ahmed, Tarek <tarek.ah...@dimdi.de> wrote: > Hi all, > > TLDR? Do you deploy one web application per tomcat instance or several? > > ----------------------- > > The long story: > > I'd like to sound out your opinion regarding the number of web > applications deployed in one tomcat instance. The reason is, that at my > place of work the developers prefer one webapp per tomcat, the admins would > rather have as many webapps as possible in one tomcat instance (yeah, > that's devops at its finest ;-) ). As a developer I'm probably prejudiced, > but the argument goes as follows: > > > OPS (one tomcat, many webapps): > > - Saves memory (each tomcat has a memory footprint even without a web > application running) > > - Saves extra file systems for each tomcat (logs, tomcat installation, > temp directory) > > - Saves nagios monitoring configuration > > - Saves separate ports (security considerations) > > - Saves work distributing security patches > > > DEV (one webapp per tomcat) > > - Start-up time of "fat tomcats" multiplies, which leads to worsened > availablity (e.g., our fattest tomcat contains 32 web services. It takes 4 > minutes to start) > > - If one webapp goes haywire, it may crash the rest of them (OOM, no more > threads, etc.) > > - For bug fixes in one application, you may need to restart the complete > tomcat instance. Auto (re)deploy takes you only so far, since loaded > classes may not always be unloaded cleanly, threads not closed etc. This is > not always something that can be solved in your own code, third party > libraries may cause problems, too (we had some issues with quartz and > infinispan here). > > - If you ever need to profile your application in production, there is > much less noise when analysing heap, thread dumps, cpu usage etc. > > - I might even think there is some improved security if webapps are > isolated in several processes vs. being deployed in one VM (security > arguments always work well with OPS :-) ) > > > So, I want to get away from the one-tomcat-multiple-webapps scenario. One > thing I started doing to subvert this policy is using spring boot with > embedded tomcats which is cool in a lot of ways but not always feasible. > > What are your practices? Are there further pros and cons for one way or > the other? Thanks so much for any input, > > many greetings, > > tarek > > -- > Tarek Ahmed > Softwareentwicklung > > > DIMDI > Deutsches Institut für > Medizinische Dokumentation und Information > Waisenhausgasse 36-38a > 50676 Köln > > Tel.: +49 221 4724-268 > Fax: +49 221 4724-444 > tarek.ah...@dimdi.de > www.dimdi.de > > [image: tick] Das DIMDI unterstützt die Vereinbarkeit von Beruf und > Familie und ist entsprechend zertifiziert. > > > Das DIMDI ist ein Institut im Geschäftsbereich des Bundesministeriums für > Gesundheit (BMG). >
