Hi Ganesh, The most up to date instructions for upgrading Nifi can be found here: https://cwiki.apache.org/confluence/display/NIFI/Upgrading+NiFi
To answer your specific questions: Yes - It is required to suspend all activity on the entire Nifi cluster before upgrading, and ensure that there is no data in the flows as it won't be kept between migrations. The steps to do this without having data loss during the upgrade is documented in the link above. Yes - This can be done via Nifi REST API in fact any operation you can do via the web ui you can do via the REST API. You can find the documentation for this here: https://nifi.apache.org/docs/nifi-docs/rest-api/index.html Both the dev and user mailing lists has plenty examples of how start automating things in Nifi, a quick search through those lists might help you hit the ground running. Edward On Fri, 14 Aug 2020, 06:24 Ganesh, B (Nokia - IN/Bangalore), < b.gan...@nokia.com> wrote: > Hi , > > We have requirement to upgrade version of Nifi-cluster without incurring > service downtime or without affecting data-loss. > For that, is it necessary to suspend the current template running in Nifi > before start of the version upgrade activity? If yes, whether there is any > programmatic way (i.e. through REST call or some other java API based > mechanism) to suspend and resume the complete template running in Nifi? > If your answer is no to the former question, can you please point us to > the relevant design documentation in Nifi internal which enables this nice > functionality i.e. version upgrade possibility without service downtime and > data loss in Nifi-cluster. > > Thanks & Regards, > Ganesh. >