fix(blooms): Do not restart builders when planner disconnects (backpo…

…rt k227) (#14922)

Co-authored-by: Salva Corts <salva.corts@grafana.com>

pkg/bloombuild/builder/builder.go

@@ -3,7 +3,9 @@ package builder
 import (
 	"context"
 	"fmt"
+	"io"
 	"os"
+	"strings"
 	"sync"
 	"time"
 
@@ -136,16 +138,39 @@ func (b *Builder) running(ctx context.Context) error {
 	retries := backoff.New(ctx, b.cfg.BackoffConfig)
 	for retries.Ongoing() {
 		err := b.connectAndBuild(ctx)
-		if err == nil || errors.Is(err, context.Canceled) {
-			break
+		if err != nil {
+			err := standardizeRPCError(err)
+
+			// When the builder is shutting down, we will get a context canceled error
+			if errors.Is(err, context.Canceled) && b.State() != services.Running {
+				level.Debug(b.logger).Log("msg", "builder is shutting down")
+				break
+			}
+
+			// If the planner disconnects while we are sending/receive a message we get an EOF error.
+			// In this case we should reset the backoff and retry
+			if errors.Is(err, io.EOF) {
+				level.Error(b.logger).Log("msg", "planner disconnected. Resetting backoff and retrying", "err", err)
+				retries.Reset()
+				continue
+			}
+
+			// Otherwise (e.g. failed to connect to the builder), we should retry
+			code := status.Code(err)
+			level.Error(b.logger).Log("msg", "failed to connect and build. Retrying", "retry", retries.NumRetries(), "maxRetries", b.cfg.BackoffConfig.MaxRetries, "code", code.String(), "err", err)
+			retries.Wait()
+			continue
 		}
 
-		level.Error(b.logger).Log("msg", "failed to connect and build. Retrying", "err", err)
-		retries.Wait()
+		// We shouldn't get here. If we do, we better restart the builder.
+		// Adding a log line for visibility
+		level.Error(b.logger).Log("msg", "unexpected end of connectAndBuild. Restarting builder")
+		break
 	}
 
 	if err := retries.Err(); err != nil {
 		if errors.Is(err, context.Canceled) {
+			// Edge case when the builder is shutting down while we check for retries
 			return nil
 		}
 		return fmt.Errorf("failed to connect and build: %w", err)
@@ -154,6 +179,31 @@ func (b *Builder) running(ctx context.Context) error {
 	return nil
 }
 
+// standardizeRPCError converts some gRPC errors we want to handle differently to standard errors.
+// 1. codes.Canceled -> context.Canceled
+// 2. codes.Unavailable with EOF -> io.EOF
+// 3. All other errors are returned as is.
+func standardizeRPCError(err error) error {
+	if err == nil {
+		return nil
+	}
+
+	if st, ok := status.FromError(err); ok {
+		switch st.Code() {
+		case codes.Canceled:
+			// Happens when the builder is shutting down, and we are sending/receiving a message
+			return context.Canceled
+		case codes.Unavailable:
+			// We want to handle this case as a retryable error that resets the backoff
+			if i := strings.LastIndex(st.Message(), "EOF"); i != -1 {
+				return io.EOF
+			}
+		}
+	}
+
+	return err
+}
+
 func (b *Builder) plannerAddress() string {
 	if b.ringWatcher == nil {
 		return b.cfg.PlannerAddress
@@ -173,8 +223,7 @@ func (b *Builder) connectAndBuild(ctx context.Context) error {
 		return fmt.Errorf("failed to create grpc dial options: %w", err)
 	}
 
-	// nolint:staticcheck // grpc.DialContext() has been deprecated; we'll address it before upgrading to gRPC 2.
-	conn, err := grpc.DialContext(ctx, b.plannerAddress(), opts...)
+	conn, err := grpc.NewClient(b.plannerAddress(), opts...)
 	if err != nil {
 		return fmt.Errorf("failed to dial bloom planner: %w", err)
 	}
@@ -202,21 +251,17 @@ func (b *Builder) connectAndBuild(ctx context.Context) error {
 }
 
 func (b *Builder) builderLoop(c protos.PlannerForBuilder_BuilderLoopClient) error {
+	ctx := c.Context()
+
 	// Send ready message to planner
 	if err := c.Send(&protos.BuilderToPlanner{BuilderID: b.ID}); err != nil {
 		return fmt.Errorf("failed to send ready message to planner: %w", err)
 	}
 
-	for b.State() == services.Running {
-		// When the planner connection closes, an EOF or "planner shutting down" error is returned.
-		// When the builder is shutting down, a gRPC context canceled error is returned.
+	// Will break when planner<->builder connection is closed or when the builder is shutting down.
+	for ctx.Err() == nil {
 		protoTask, err := c.Recv()
 		if err != nil {
-			if status.Code(err) == codes.Canceled {
-				level.Debug(b.logger).Log("msg", "builder loop context canceled")
-				return nil
-			}
-
 			return fmt.Errorf("failed to receive task from planner: %w", err)
 		}
 
@@ -235,7 +280,7 @@ func (b *Builder) builderLoop(c protos.PlannerForBuilder_BuilderLoopClient) erro
 			continue
 		}
 
-		newMetas, err := b.processTask(c.Context(), task)
+		newMetas, err := b.processTask(ctx, task)
 		if err != nil {
 			err = fmt.Errorf("failed to process task: %w", err)
 		}
@@ -249,8 +294,8 @@ func (b *Builder) builderLoop(c protos.PlannerForBuilder_BuilderLoopClient) erro
 		b.metrics.processingTask.Set(0)
 	}
 
-	level.Debug(b.logger).Log("msg", "builder loop stopped")
-	return nil
+	level.Debug(b.logger).Log("msg", "builder loop stopped", "ctx_err", ctx.Err())
+	return ctx.Err()
 }
 
 func (b *Builder) logTaskCompleted(