[dmattia]

Say I have a pico cluster with a few service nodes and a few upstream clients register themselves, and then I deploy a new version of the service nodes where all existing service nodes are taken down and replaced.

Can the client still talk to the service nodes? Is this over the same tunnel, or does the agent need to create a new tunnel? What happens to requests that are sent from a proxy-client to the service nodes during this transition?

Or at a much higher level: Can I deploy new service nodes without downtime?

[andydunstall]

When Pico server nodes are replaced, the upstreams will automatically reconnect to a new node, then that node will propagate the new routing information to the other nodes in the cluster

So if you have a single upstream for an endpoint, when the upstream reconnects there may be a second where it isn't connected but will recover quickly (planning to add retries in the future to handle this more gracefully)

Similarly if a server node fails the upstream can reconnect