Hello,

The short answer is that you currently can't do a true zero downtime
deployment of NARs.

The longer answer...

When a node joins the cluster there is a comparison done between the
node's flow and the node's NARs against the cluster's flow and
cluster's NARs. In the case of the flow, if the node's flow is empty
then it can inherit the flow from the cluster, but in the case of the
NARs the node is required to have the same set of NARs as the cluster
to ensure consistency (i.e. it would be bad if some nodes had a custom
NAR that other nodes didn't have). This is the same scenario for an
upgrade where you have an existing cluster running with say all NARs
from 1.5.0 and then you upgrade one node to 1.6.0, it won't be able to
join the cluster because it has a different set of NARs, so you have
to upgrade all nodes at the same time so that when the cluster forms
it starts as 1.6.0.

I think the process for deploying NARs will become better in the
future with some of the ideas that have been discussed regarding the
extension registry. The goal would be to deploy a new NAR without
restarting any nodes by uploading it to the extension registry and
having NiFi automatically download it and make it available.

-Bryan



On Mon, May 28, 2018 at 3:17 PM, Paul Hadrosek
<[email protected]> wrote:
> I have a three node nifi cluster and I want to deploy nars and an updated
> flow.xml file without taking down the cluster. Below is my proposed process:
>
> Remove each nifi worker from the cluster. Deploy the nars and flow.xml file.
> Restart each nifi worker node.
> Deploy updated nars and a flow.xml file to the primary node, Restart the
> primary nifi node.
> Add each worker node back into the cluster.
>
> Is this correct? Are there other alternatives?
>
> Thanks
>
> --
> Paul Hadrosek
> Principal Solutions Architect
> iNovex Information Systems
> 301.873.2523(Cell)
>
> http://www.inovexcorp.com
> [email protected]
>
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