In this mode, the node is not reachable from the outside, i.e.
* it refuses all incoming RPC connections,
* it does not join the cluster, thus
* all group0 operations are disabled (e.g. schema changes),
* all cluster-wide operations are disabled for this node (e.g. repair),
* other nodes see this node as dead,
* cannot read or write data from/to other nodes,
* it does not open Alternator and Redis transport ports and the TCP CQL port.
The only way to make CQL queries is to use the maintenance socket. The node serves only local data.
To start the node in maintenance mode, use the `--maintenance-mode true` flag or set `maintenance_mode: true` in the configuration file.
REST API works as usual, but some routes are disabled:
* authorization_cache
* failure_detector
* hinted_hand_off_manager
This PR also updates the maintenance socket documentation:
* add cqlsh usage to the documentation
* update the documentation to use `WhiteListRoundRobinPolicy`
Fixes#5489.
Closesscylladb/scylladb#15346
* github.com:scylladb/scylladb:
test.py: add test for maintenance mode
test.py: generalize usage of cluster_con
test.py: when connecting to node in maintenance mode use maintenance socket
docs: add maintenance mode documentation
main: add maintenance mode
main: move some REST routes initialization before joining group0
message_service: add sanity check that rpc connections are not created in the maintenance mode
raft_group0_client: disable group0 operations in the maintenance mode
service/storage_service: add start_maintenance_mode() method
storage_service: add MAINTENANCE option to mode enum
service/maintenance_mode: add maintenance_mode_enabled bool class
service/maintenance_mode: move maintenance_socket_enabled definition to seperate file
db/config: add maintenance mode flag
docs: add cqlsh usage to maintenance socket documentation
docs: update maintenance socket documentation to use WhiteListRoundRobinPolicy
4f736894e1