From 3f9103c8aad311f974f1657ccc12354b1ea400f7 Mon Sep 17 00:00:00 2001
From: Andrea Luzzardi <aluzzardi@gmail.com>
Date: Thu, 15 Apr 2021 01:15:01 -0700
Subject: [PATCH] buildkit: support concurrent starts

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>
---
 pkg/buildkitd/buildkitd.go | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/pkg/buildkitd/buildkitd.go b/pkg/buildkitd/buildkitd.go
index e3b93f82..f6effa61 100644
--- a/pkg/buildkitd/buildkitd.go
+++ b/pkg/buildkitd/buildkitd.go
@@ -116,13 +116,18 @@ func startBuildkit(ctx context.Context) error {
 	)
 	output, err = cmd.CombinedOutput()
 	if err != nil {
-		log.
-			Ctx(ctx).
-			Error().
-			Err(err).
-			Bytes("output", output).
-			Msg("unable to start buildkitd")
-		return err
+		// If the daemon failed to start because it's already running,
+		// chances are another dagger instance started it. We can just ignore
+		// the error.
+		if !strings.Contains(string(output), "Error response from daemon: Conflict.") {
+			log.
+				Ctx(ctx).
+				Error().
+				Err(err).
+				Bytes("output", output).
+				Msg("unable to start buildkitd")
+			return err
+		}
 	}
 	return waitBuildkit(ctx)
 }