feat(api): Add a /ready endpoint (#192)

* Add a /ready endpoint

This helps to know when the node is on sync with the data on the chain.

Changed the /health response to have the same format as the /ready one.

Signed-off-by: Antonio Navarro Perez <antnavper@gmail.com>

* linter

Signed-off-by: Antonio Navarro Perez <antnavper@gmail.com>

* linter field alignment

Signed-off-by: Antonio Navarro Perez <antnavper@gmail.com>

* linter line lenght

Signed-off-by: Antonio Navarro Perez <antnavper@gmail.com>

---------

Signed-off-by: Antonio Navarro Perez <antnavper@gmail.com>

Author: ajnavarro

cmd/start.go

@@ -197,7 +197,7 @@ func (c *startCfg) exec(ctx context.Context) error {
 
 	mux = j.SetupRoutes(mux)
 	mux = graph.Setup(db, em, mux, c.disableIntrospection)
-	mux = health.Setup(db, mux)
+	mux = health.Setup(db, f, mux)
 
 	// Create the HTTP server
 	hs := serve.NewHTTPServer(mux, c.listenAddress, logger.Named("http-server"))

fetch/fetch.go

@@ -8,12 +8,12 @@ import (
 	"sort"
 	"time"
 
-	queue "github.com/madz-lab/insertion-queue"
-	"go.uber.org/zap"
-
 	"github.com/gnolang/gno/gno.land/pkg/gnoland"
 	"github.com/gnolang/gno/tm2/pkg/amino"
 	bft_types "github.com/gnolang/gno/tm2/pkg/bft/types"
+	queue "github.com/madz-lab/insertion-queue"
+	"go.uber.org/zap"
+
 	"github.com/gnolang/tx-indexer/storage"
 	storageErrors "github.com/gnolang/tx-indexer/storage/errors"
 	"github.com/gnolang/tx-indexer/types"
@@ -36,8 +36,9 @@ type Fetcher struct {
 	logger      *zap.Logger
 	chunkBuffer *slots
 
-	maxSlots     int
-	maxChunkSize int64
+	maxSlots        int
+	maxChunkSize    int64
+	latestChunkSize int
 
 	queryInterval time.Duration // block query interval
 }
@@ -316,9 +317,25 @@ func (f *Fetcher) writeSlot(s *slot) error {
 		return fmt.Errorf("error persisting block information into storage, %w", err)
 	}
 
+	f.latestChunkSize = len(s.chunk.blocks)
+
 	return nil
 }
 
+func (f *Fetcher) IsReady() (bool, error) {
+	if f.latestChunkSize == int(f.maxChunkSize) {
+		return false, fmt.Errorf("the data synchronization process is still in progress and hasn't "+
+			"caught up with the current blockchain state. Chunk size: %d", f.latestChunkSize)
+	}
+
+	_, err := f.client.GetLatestBlockNumber()
+	if err != nil {
+		return false, fmt.Errorf("node RPC method is not reachable: %w", err)
+	}
+
+	return true, nil
+}
+
 func getGenesisBlock(client Client) (*bft_types.Block, error) {
 	gblock, err := client.GetGenesis()
 	if err != nil {

fetch/options.go

@@ -25,5 +25,6 @@ func WithMaxSlots(maxSlots int) Option {
 func WithMaxChunkSize(maxChunkSize int64) Option {
 	return func(f *Fetcher) {
 		f.maxChunkSize = maxChunkSize
+		f.latestChunkSize = int(maxChunkSize)
 	}
 }

serve/health/health.go

@@ -11,20 +11,61 @@ import (
 	"github.com/gnolang/tx-indexer/storage"
 )
 
-func Setup(s storage.Storage, m *chi.Mux) *chi.Mux {
+func Setup(s storage.Storage, rc ReadyChecker, m *chi.Mux) *chi.Mux {
 	m.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
 		h, err := s.GetLatestHeight()
 		if err != nil {
-			fmt.Fprintf(w, "ERROR: %s\n", err)
+			render.JSON(w, r, &response{
+				Message: fmt.Sprintf("storage is not reachable: %s", err.Error()),
+				Info: map[string]any{
+					"time": time.Now().String(),
+				},
+			})
+
+			render.Status(r, http.StatusInternalServerError)
+
+			return
+		}
+
+		render.JSON(w, r, &response{
+			Message: "Server is responding",
+			Info: map[string]any{
+				"time":   time.Now().String(),
+				"height": h,
+			},
+		})
+	})
+
+	m.HandleFunc("/ready", func(w http.ResponseWriter, r *http.Request) {
+		ok, err := rc.IsReady()
+		if !ok {
+			render.JSON(w, r, &response{
+				Message: fmt.Sprintf("node not ready: %s", err.Error()),
+				Info: map[string]any{
+					"time": time.Now().String(),
+				},
+			})
 			render.Status(r, http.StatusInternalServerError)
 
 			return
 		}
 
-		fmt.Fprintf(w, "Server is responding\n")
-		fmt.Fprintf(w, "- Time: %s\n", time.Now())
-		fmt.Fprintf(w, "- Latest Height: %d\n", h)
+		render.JSON(w, r, &response{
+			Message: "node is ready",
+			Info: map[string]any{
+				"time": time.Now().String(),
+			},
+		})
 	})
 
 	return m
 }
+
+type response struct {
+	Info    map[string]any `json:"info"`
+	Message string         `json:"message"`
+}
+
+type ReadyChecker interface {
+	IsReady() (bool, error)
+}