add explain index allocation

pkg/es/index.go

@@ -111,7 +111,7 @@ func IndexShow(conf *cfg.Config, index string) error {
 	slog.Debug("ES result", "index", res)
 
 	table := NewTable(2, 5)
-	table.Addheaders("field", "value")
+	table.Addheaders("index property", "value")
 
 	ts, err := strconv.ParseInt(res[index].Settings.Index.CreationDate.(string), 10, 64)
 	if err != nil {
@@ -216,3 +216,52 @@ func IndexClose(conf *cfg.Config, index string) error {
 
 	return nil
 }
+
+func IndexAllocation(conf *cfg.Config, index string) error {
+	if index == "" {
+		return fmt.Errorf("no index specified")
+	}
+
+	alloc := conf.DefaultCluster.ES.Cluster.AllocationExplain().
+		Index(index).
+		Primary(conf.Primary).
+		Shard(conf.Shards)
+
+	res, err := alloc.Header("content-type", "application/json").
+		Header("accept", "application/json").
+		Do(context.Background())
+	if err != nil {
+		return fmt.Errorf("failed to get index allocation explain: %s", err)
+	}
+
+	slog.Debug("ES result", "index", res)
+
+	currentNode := res.CurrentNode
+
+	table := NewTable(2, 10)
+	table.Addheaders("index allocation setting", "value")
+
+	roles := make([]string, len(currentNode.Roles))
+	for idx, role := range currentNode.Roles {
+		roles[idx] = role.Name
+	}
+
+	table.entries = [][]string{
+		{"Index", index},
+		{"Current node", currentNode.Name},
+		{"Current k8s node", currentNode.Attributes["k8s_node_name"]},
+		{"Current node address", currentNode.TransportAddress},
+		{"Current node id", currentNode.Id},
+		{"Current node weight", fmt.Sprintf("%d", currentNode.WeightRanking)},
+		{"Current node roles", strings.Join(roles, ",")},
+		{"Can rebalance cluster", res.CanRebalanceCluster.Name},
+		{"Can rebalance to another node", res.CanRebalanceToOtherNode.Name},
+		{"Can remain on current node", res.CanRemainOnCurrentNode.Name},
+	}
+
+	if err := table.PrintMarkdown(); err != nil {
+		return err
+	}
+
+	return nil
+}