grpc: Interceptor to catch panics and convert them to Internal errors.

grpc/grpcutil/paniccatcher.go

+// Copyright 2017 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package grpcutil
+
+import (
+        "golang.org/x/net/context"
+        "google.golang.org/grpc"
+
+        "github.com/luci/luci-go/common/logging"
+        "github.com/luci/luci-go/common/runtime/paniccatcher"
+)
+
+// NewUnaryServerPanicCatcher returns a unary interceptor that catches panics
+// in RPC handlers, recovers them and returns codes.Internal gRPC errors
+// instead.
+//
+// It can be optionally chained with other interceptor.
+func NewUnaryServerPanicCatcher(next grpc.UnaryServerInterceptor) grpc.UnaryServerInterceptor {
+        return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
+                defer paniccatcher.Catch(func(p *paniccatcher.Panic) {
+                        logging.Fields{
+                                "panic.error": p.Reason,
+                        }.Errorf(ctx, "Caught panic during handling of %q: %s\n%s", info.FullMethod, p.Reason, p.Stack)
+                        err = Internal
+                })
+                if next != nil {
+                        return next(ctx, req, info, handler)
+                }
+                return handler(ctx, req)
+        }
+}