pkg: add grpcutil package (#1032)

pkg/grpcutil/grpcutil.go

@@ -0,0 +1,31 @@
+// Package grpcutil contains functions for interacting with gRPC.
+package grpcutil
+
+import (
+	"context"
+
+	"google.golang.org/grpc/metadata"
+)
+
+// SessionIDMetadataKey is the key in the metadata.
+const SessionIDMetadataKey = "sessionid"
+
+// WithOutgoingSessionID appends a metadata header for the session ID to a context.
+func WithOutgoingSessionID(ctx context.Context, sessionID string) context.Context {
+	return metadata.AppendToOutgoingContext(ctx, SessionIDMetadataKey, sessionID)
+}
+
+// SessionIDFromGRPCRequest returns the session id from the gRPC request.
+func SessionIDFromGRPCRequest(ctx context.Context) (sessionID string, ok bool) {
+	md, ok := metadata.FromIncomingContext(ctx)
+	if !ok {
+		return "", false
+	}
+
+	sessionIDs := md.Get(SessionIDMetadataKey)
+	if len(sessionIDs) == 0 {
+		return "", false
+	}
+
+	return sessionIDs[0], true
+}

pkg/grpcutil/grpcutil_test.go

@@ -0,0 +1,29 @@
+package grpcutil
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/grpc/metadata"
+)
+
+func TestWithOutgoingSessionID(t *testing.T) {
+	ctx := context.Background()
+	ctx = WithOutgoingSessionID(ctx, "EXAMPLE")
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if !assert.True(t, ok) {
+		return
+	}
+	assert.Equal(t, []string{"EXAMPLE"}, md.Get("sessionid"))
+}
+
+func TestSessionIDFromGRPCRequest(t *testing.T) {
+	ctx := context.Background()
+	ctx = metadata.NewIncomingContext(ctx, metadata.MD{
+		"sessionid": {"EXAMPLE"},
+	})
+	sessionID, ok := SessionIDFromGRPCRequest(ctx)
+	assert.True(t, ok)
+	assert.Equal(t, "EXAMPLE", sessionID)
+}