Use http://flywaydb.org/ to perform database migrations. You will need at least 3 versions in order to perform an incompatible database change. v1 is existing behavior, v2 is a shim that bridges v1 and v3, and then v3 cleans up the shim and removes all the unnecessary hacks. When you have v1 rolled out against N images, then you can start rolling out compat shim v2 which adds some temporary work for the db and coexists, then when all instances are at v2 you can move to v3 which uses all the new stuff.
I haven't found anything better or more efficient than the 2-step deployment with live code. On Thu, Dec 3, 2015 at 2:21 PM, Kevin Hale Boyes <kcbo...@gmail.com> wrote: > Thanks for this link to the presentation. > How do you all deal with some of the other dependencies that the web > application has? > > For example, if v2 of my application needs new database columns or worse, a > change to an existing column how can I have v1 and v2 running at the same > time? We use Oracle as our database though the problem exists for many > database servers. > > Thanks, > Kevin. > > On 3 December 2015 at 01:31, Neill Lima <neill.l...@visual-meta.com> wrote: > >> Hello Jason, >> >> This approach of using httpd in front of 2+ Tomcats via AJP works well in >> my company. There is a bit of config necessary at httpd level so httpd is >> aware of all the Tomcats and also Tomcat config needs to be set to listen >> to AJP port instead of default port but it is not rocket science. >> >> This facilitates the deployment of nodes sequentially with no downtime. Of >> course, there is a shared session server to take care the sessions are not >> lost when Tomcats flip up and down. >> >> Reply in pvt if you need help setting up this. >> >> Thanks, >> >> Neill >> >> On Thu, Dec 3, 2015 at 12:08 AM, Jason Britton <jbritto...@gmail.com> >> wrote: >> >> > Thank you Christopher, reading now and we'll see if I can swing the >> > conference :) >> > >> > On Wed, Dec 2, 2015 at 4:00 PM, Christopher Schultz < >> > ch...@christopherschultz.net> wrote: >> > >> > > Jason, >> > > >> > > On 12/2/15 4:07 PM, Jason Britton wrote: >> > > > I was looking for information for how those on the list achieve zero >> > > > downtime deployments of their tomcat hosted web applications. I >> > imagine >> > > > this can be achieved in a variety of ways, but would love to hear >> what >> > > > works for you. In our current environment we front multiple tomcat >> > > > instances with apache httpd, each tomcat instance hosting one or more >> > > > unique web apps. In order to support this effort we do have the >> > > resources >> > > > where we could spin up multiple tomcat instances to serve requests >> for >> > a >> > > > single application. I know there is mod_proxy_balancer available for >> > > > httpd, and I understand starting with tomcat 7 there is support for >> > > > parallel deployment of versioned wars, and tomcat also supports >> > > > clustering. I'm just unsure of what approach I should start digging >> > into >> > > > and would very much appreciate any of your experiences. The servers >> > > we'll >> > > > be rolling out will be using the latest versions of tomcat 8 and >> apache >> > > > httpd 2.4. Thanks for any insights! >> > > >> > > Check this out: >> > > >> > > >> > >> http://people.apache.org/~schultz/ApacheCon%20NA%202015/Load-balancing%20Tomcat%20with%20mod_jk.pdf >> > > >> > > Start on slide/page 41. >> > > >> > > Then come to ApacheCon NA 2016 and discuss it! >> > > >> > > -chris >> > > >> > > --------------------------------------------------------------------- >> > > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >> > > For additional commands, e-mail: users-h...@tomcat.apache.org >> > > >> > > >> > >> --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
