tt replicaset upgrade upgrades database schema.

[TarantoolBot]

Product: tt cli
Since: tt 2.5.0
Audience/target: all
Root document: https://www.tarantool.io/en/doc/latest/reference/tooling/tt_cli/replicaset/
SME: @ mandesero @ oleg-jukovec

Details

The tt replicaset upgrade command allows for a automate upgrade of each
replicaset in a Tarantool cluster. The process is performed sequentially on
the master instance and its replicas to ensure data consistency. Below are
the steps involved:

For Each Replicaset:

• On the Master Instance:

  1. Run the following commands in sequence to upgrade the schema and take
     a snapshot:

     box.schema.upgrade()
     box.snapshot()

• On Each Replica:

  1. Wait for the replica to apply all transactions produced by the
     box.schema.upgrade() command executed on the master. This is done
     by monitoring the vector clocks (vclock) to ensure synchronization.
  2. Once the repica has caught up, run the following command to take
     a snapshot:

     box.snapshot()

Error Handling: If any errors occur during the upgrade process, the
operation will halt, and an error report will be generated.

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• Timeout for Synchronization

Replicas will wait for synchronization for a maximum of Timeout seconds.
The default timeout is set to 5 seconds, but this can be adjusted manually
using the --timeout option.

Example:

$ tt replicaset upgrade [<APP_NAME>] --timeout 10

• Selecting Replicasets for Upgrade

You can specify which replicaset(s) to upgrade by using the --replicaset
or -r option to target specific replicaset names.

Example:

$ tt replicaset upgrade [<APP_NAME> | <URI>] --replicaset <RS_NAME_1> -r <RS_NAME_2> ...

This provides flexibility in upgrading only the desired parts of the cluster
without affecting the entire system.
Requested by @mandesero in tarantool/tt@d9d2545.

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To be done together with #4661