Upgrade order (best practices)

When upgrading a service (i.e. such as a spring boot application that uses the elasticsearch client library), and also an ElasticSearch cluster, to use a new version (say an upgrade from 1.6.0 to 1.6.2), what order is best practices?

I assume upgrading the service first, so it can startup using the newer elasticsearch client library 1.6.2 against an older ES cluster running 1.6.0, and then after that upgrade the cluster. I only assume that since the client library is likely backward compatible.

With such a small step you shouldn't really have to worry either way.

Those were just example versions. I was more curious about best practices? So, in a more extreme case, if I was going from 1.4.2 to 1.7.1 what would be recommended (although I'd likely never get that outdated).

It'd probably be better to upgrade ES and then the client.

But caveat; Larger versions are trickier and you really want to go over the change notes and readmes to make sure this will work.