overriding configuration on a running tarantool instance

Question

Can anyone tell me in the course, it is possible to override the parameters of individual box.cfg on a running instance. For example, add a replica, for several days I have been trying to deploy three replicas on three hosts via the docker service stack. When I raise my hands on each server, everything works, through deploy they do not see each other and fall. I've tried all sorts of ways. hung up the endpoint on the target nodes, when requested, it gives the ip of the machine on which the container rises, if the ip matches one of those indicated in SEED, then substitutes the internal ip of the container instead (otherwise it cannot connect to itself). In theory, it all works as I described, but there are suspicions that everything is not much different, I suppose that the problem is that before the declaration of box.cfg the instance does not reserve the address. Alas, I can not go inside the container because it cannot rise. I got the idea that if all three nodes are declared at the minimum settings and as soon as they rise to listen to the subnet, as soon as the node finds another, it will write it to replication and override box.cfg. Correct me please who had experience.

Answer 1

Some of the box.cfg parameters are dynamic. For example, the box.cfg{listen=}. You can set this one from the Lua code as you wish. In your case, if the container gets its IP address later, you need to specify only the port in listen. This way, Tarantool will listen on all possible interfaces.

The replication_source is a bit trickier. You can set it dynamically, but your first (initializing) call to box.cfg should be with the replication_source. This is because all instances that are initialized without this parameter will create their own replicaset, and it will make it impossible to join them to another replicaset.

You can read more about Tarantool replication architecture here: https://www.tarantool.io/en/doc/latest/book/replication/repl_architecture/