Learner Node is not working

[MichelDiz]

Describe the bug

Supposedly, the Learner node would be an instance of Dgraph outside of the RAFT Group. There is no in-depth material on the subject. This makes it difficult to effectively test it. However, in theory, we should have an instance that would supposedly be a replica for readonly.

What is still unknown to me is whether the replica would be total for the entire cluster or individual for each group/shard. The second option would be a bit strange. But plausible.

To Reproduce

Steps to reproduce the behavior:

I have created a cluster with 1 zero and 3 alphas. After I tried run a Learner Alpha and no luck.

go run main.go alpha --zero 0.0.0.0:5080 --security "whitelist=0.0.0.0/0;" --my 0.0.0.0:7090 --tmp alphaLearner/t -p=alphaLearner/p -w=alphaLearner/w -o=10 --raft "learner=true;"

In order to effectively test it, I had to comment out a line in the code that was forcing a fatal error.

	// if n.RaftContext.IsLearner && !hasPeer {
	// 	glog.Fatal("Cannot start a learner node without peer alpha nodes")
	// }

I think the issue here(the fatal one) is due to lack of flag value propagation.

Expected behavior

To work

Environment

• OS: macOS
• Language Go
• Version Latest Main - v25.0.0-preview1

Additional context

Investigations

At this line

dgraph/worker/groups.go

Line 96 in e01eebd

m := &pb.Member{

I saw that the Learner flag was activated.
But in the state it is "learner": false, sounds like the flag is not being propagated.

[linear]

DGR-882 Learner Node is not working