[vtadmin] Add FindSchema route

go/vt/vtadmin/api.go

@@ -29,6 +29,7 @@ import (
 
 	"vitess.io/vitess/go/trace"
 	"vitess.io/vitess/go/vt/concurrency"
+	"vitess.io/vitess/go/vt/log"
 	"vitess.io/vitess/go/vt/topo"
 	"vitess.io/vitess/go/vt/topo/topoproto"
 	"vitess.io/vitess/go/vt/vtadmin/cluster"
@@ -88,6 +89,7 @@ func NewAPI(clusters []*cluster.Cluster, opts grpcserver.Options, httpOpts vtadm
 	router.HandleFunc("/clusters", httpAPI.Adapt(vtadminhttp.GetClusters)).Name("API.GetClusters")
 	router.HandleFunc("/gates", httpAPI.Adapt(vtadminhttp.GetGates)).Name("API.GetGates")
 	router.HandleFunc("/keyspaces", httpAPI.Adapt(vtadminhttp.GetKeyspaces)).Name("API.GetKeyspaces")
+	router.HandleFunc("/schema/{table}", httpAPI.Adapt(vtadminhttp.FindSchema)).Name("API.FindSchema")
 	router.HandleFunc("/schema/{cluster_id}/{keyspace}/{table}", httpAPI.Adapt(vtadminhttp.GetSchema)).Name("API.GetSchema")
 	router.HandleFunc("/schemas", httpAPI.Adapt(vtadminhttp.GetSchemas)).Name("API.GetSchemas")
 	router.HandleFunc("/tablets", httpAPI.Adapt(vtadminhttp.GetTablets)).Name("API.GetTablets")
@@ -125,6 +127,81 @@ func (api *API) ListenAndServe() error {
 	return api.serv.ListenAndServe()
 }
 
+// FindSchema is part of the vtadminpb.VTAdminServer interface.
+func (api *API) FindSchema(ctx context.Context, req *vtadminpb.FindSchemaRequest) (*vtadminpb.Schema, error) {
+	span, _ := trace.NewSpan(ctx, "API.FindSchema")
+	defer span.Finish()
+
+	span.Annotate("table", req.Table)
+
+	clusters, _ := api.getClustersForRequest(req.ClusterIds)
+
+	var (
+		m       sync.Mutex
+		wg      sync.WaitGroup
+		rec     concurrency.AllErrorRecorder
+		results []*vtadminpb.Schema
+	)
+
+	for _, c := range clusters {
+		wg.Add(1)
+
+		go func(c *cluster.Cluster) {
+			defer wg.Done()
+
+			tablets, err := c.FindTablets(ctx, func(t *vtadminpb.Tablet) bool {
+				// Filter out all the non-serving tablets once, to make the
+				// later, per-keyspace filtering slightly faster (fewer
+				// potentially-redundant iterations).
+				return t.State == vtadminpb.Tablet_SERVING
+			}, -1)
+			if err != nil {
+				err := fmt.Errorf("could not find any serving tablets for cluster %s: %w", c.ID, err)
+				rec.RecordError(err)
+
+				return
+			}
+
+			schemas, err := api.getSchemas(ctx, c, tablets)
+			if err != nil {
+				err := fmt.Errorf("%w: while collecting schemas for cluster %s", err, c.ID)
+				rec.RecordError(err)
+
+				return
+			}
+
+			for _, schema := range schemas {
+				for _, td := range schema.TableDefinitions {
+					if td.Name == req.Table {
+						m.Lock()
+						results = append(results, schema)
+						m.Unlock()
+
+						return
+					}
+				}
+			}
+
+			log.Infof("cluster %s has no tables named %s", c.ID, req.Table)
+		}(c)
+	}
+
+	wg.Wait()
+
+	if rec.HasErrors() {
+		return nil, rec.Error()
+	}
+
+	switch len(results) {
+	case 0:
+		return nil, fmt.Errorf("%w: no schemas found with table named %s", errors.ErrNoSchema, req.Table)
+	case 1:
+		return results[0], nil
+	default:
+		return nil, fmt.Errorf("%w: %d schemas found with table named %s", errors.ErrAmbiguousSchema, len(results), req.Table)
+	}
+}
+
 // GetClusters is part of the vtadminpb.VTAdminServer interface.
 func (api *API) GetClusters(ctx context.Context, req *vtadminpb.GetClustersRequest) (*vtadminpb.GetClustersResponse, error) {
 	span, _ := trace.NewSpan(ctx, "API.GetClusters")