On Mon, Jan 7, 2019 at 3:37 PM Jonathan Ballet <jbal...@edgelab.ch> wrote:
> > I'm working on how we could improve the upgrades of our servers and how to > replace them completely (new instance with a new IP address). > What I would like to do is to replace the machines holding our current > seeds (#1 and #2 at the moment) in a rolling upgrade fashion, on a regular > basis: > > * Is it possible to "promote" any non-seed node as a seed node? > > * Is it possible to "promote" a new seed node without having to restart > all the nodes? > In essence, in my example that would be: > > - decide that #2 and #3 will be the new seed nodes > - update all the configuration files of all the nodes to write the IP > addresses of #2 and #3 > - DON'T restart any node - the new seed configuration will be picked up > only if the Cassandra process restarts > You can provide a custom implementation of the seed provider protocol: org.apache.cassandra.locator.SeedProvider We were exploring that approach few years ago with etcd, which I think provides capabilities similar to that of Consul: https://github.com/a1exsh/cassandra-etcd-seed-provider/blob/master/src/main/java/org/zalando/cassandra/locator/EtcdSeedProvider.java We are not using this anymore, but for other reasons (namely, being too optimistic about putting Cassandra cluster into an AWS AutoScaling Group). The SeedProvider itslef seem to have worked as we have expected. Hope this helps, -- Alex
