How can I start a member as a read-only member? about nuraft

[greensky00]

Hi @ZTJiu

In srv_config, there is a boolean flag indicating whether it is a learner:

NuRaft/include/libnuraft/srv_config.hxx

Lines 108 to 112 in 498cc30

	/**
	* `true` if this node is learner.
	* Learner will not initiate or participate in leader election.
	*/
	bool learner_;

You can make the flag true, and use it for initializing s2

NuRaft/examples/in_memory_state_mgr.hxx

Line 34 in 498cc30

my_srv_config_ = cs_new<srv_config>( srv_id, endpoint );

then s2 will not be a leader at the beginning.

After that, you can use the same srv_config for adding s2 to the leader.

NuRaft/include/libnuraft/raft_server.hxx

Lines 114 to 125 in 498cc30

	/**
	* Add a new server to the current cluster.
	* Only leader will accept this operation.
	* Note that this is an asynchronous task so that needs more network
	* communications. Returning this function does not guarantee
	* adding the server.
	*
	* @param srv Configuration of server to add.
	* @return `get_accepted()` will be true on success.
	*/
	ptr< cmd_result< ptr<buffer> > >
	add_srv(const srv_config& srv);

Once adding a learner is successfully done, you can see a log like this:

2020-06-02T10:46:15.276_630-07:00 [8d67] [INFO] new configuration: log idx 4, prev log idx 3
peer 1, DC ID 1, tcp://127.0.0.1:11111, voting member, 50
peer 2, DC ID 1, tcp://127.0.0.1:11112, voting member, 50
peer 3, DC ID 1, tcp://127.0.0.1:11113, voting member, 50
peer 4, DC ID 1, tcp://127.0.0.1:11114, learner, 50
my id: 1, leader: 1, term: 1    [handle_commit.cxx:693, reconfigure()]

[ZTJiu]

Hi @greensky00
It works. Thanks a lot!