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feat: add cluster name to leaf monitoring data #7981

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feat: add cluster name to leaf monitoring data #7981

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2 changes: 2 additions & 0 deletions server/monitor.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2364,6 +2364,7 @@ type LeafzOptions struct {
type LeafInfo struct {
ID uint64 `json:"id"`
Name string `json:"name"`
Cluster string `json:"cluster,omitempty"`
IsSpoke bool `json:"is_spoke"`
IsIsolated bool `json:"is_isolated,omitempty"`
Account string `json:"account"`
Expand Down Expand Up @@ -2409,6 +2410,7 @@ func (s *Server) Leafz(opts *LeafzOptions) (*Leafz, error) {
lni := &LeafInfo{
ID: ln.cid,
Name: ln.leaf.remoteServer,
Cluster: ln.leaf.remoteCluster,
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@chatgpt-codex-connector chatgpt-codex-connector Bot Mar 23, 2026

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P2 Badge Hide synthetic leaf cluster names from /leafz

When a remote leaf has leafnodes.remotes and a server_name but no cluster block, Server.New intentionally fabricates opts.Cluster.Name = opts.ServerName only for internal bookkeeping (server/server.go:820-825), and /varz already strips that back out (server/monitor.go:1708-1711). leafNodeResumeConnectProcess still sends this synthetic value in the leaf CONNECT (server/leafnode.go:3367-3375, server/leafnode.go:976-978), so exposing ln.leaf.remoteCluster here makes /leafz report standalone leaves as if they belonged to a real cluster named after the server. Any topology consumer using /leafz will misclassify non-clustered leaves whenever server_name is configured.

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IsSpoke: ln.isSpokeLeafNode(),
IsIsolated: ln.leaf.isolated,
Account: ln.acc.Name,
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51 changes: 51 additions & 0 deletions server/monitor_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4263,6 +4263,57 @@ func TestMonitorLeafz(t *testing.T) {
}
}

func TestMonitorLeafzCluster(t *testing.T) {
hubConf := createConfFile(t, []byte(`
server_name: "hub"
listen: "127.0.0.1:-1"
http: "127.0.0.1:-1"
leafnodes {
listen: "127.0.0.1:-1"
}
`))
hub, hubOpts := RunServerWithConfig(hubConf)
defer hub.Shutdown()

leafConf := createConfFile(t, []byte(fmt.Sprintf(`
server_name: "leaf1"
listen: "127.0.0.1:-1"
cluster {
name: "leaf-cluster"
listen: "127.0.0.1:-1"
}
leafnodes {
remotes = [{
url: "nats-leaf://127.0.0.1:%d"
}]
}
`, hubOpts.LeafNode.Port)))
leaf, _ := RunServerWithConfig(leafConf)
defer leaf.Shutdown()

checkLeafNodeConnected(t, leaf)

// Make sure the hub sees the remote cluster name of the leaf node.
l, err := hub.Leafz(nil)
require_NoError(t, err)
require_Equal(t, l.NumLeafs, 1)
require_Equal(t, len(l.Leafs), 1)
require_Equal(t, l.Leafs[0].Cluster, "leaf-cluster")
require_Equal(t, l.Leafs[0].Name, "leaf1")

// Make sure from the leaf's perspective, the hub has no cluster.
l, err = leaf.Leafz(nil)
require_NoError(t, err)
require_Equal(t, l.NumLeafs, 1)
require_Equal(t, len(l.Leafs), 1)
require_Equal(t, l.Leafs[0].Cluster, "")
require_Equal(t, l.Leafs[0].Name, "hub")

// Make sure that cluster is present in the HTTP response as well.
body := readBody(t, fmt.Sprintf("http://127.0.0.1:%d/leafz", hub.MonitorAddr().Port))
require_True(t, strings.Contains(string(body), `"cluster": "leaf-cluster"`))
}

func pollAccountz(t *testing.T, s *Server, mode int, url string, opts *AccountzOptions) *Accountz {
t.Helper()
if mode == 0 {
Expand Down
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