tests: set a dedicated buildx config dir for each worker

This should help reduce any unexpected config conflict between workers.

Signed-off-by: Justin Chadwell <me@jedevc.com>

tests/integration.go

@@ -47,6 +47,7 @@ func buildxCmd(sb integration.Sandbox, opts ...cmdOpt) *exec.Cmd {
 
 	if builder := sb.Address(); builder != "" {
 		cmd.Args = append(cmd.Args, "--builder="+builder)
+		cmd.Env = append(cmd.Env, "BUILDX_CONFIG=/tmp/buildx-"+builder)
 	}
 	if context := sb.DockerAddress(); context != "" {
 		cmd.Env = append(cmd.Env, "DOCKER_CONTEXT="+context)

tests/workers/docker-container.go

@@ -50,7 +50,11 @@ func (w *containerWorker) New(ctx context.Context, cfg *integration.BackendConfi
 		"--driver=docker-container",
 		"--driver-opt=network=host",
 	)
-	cmd.Env = append(os.Environ(), "DOCKER_CONTEXT="+w.docker.DockerAddress())
+	cmd.Env = append(
+		os.Environ(),
+		"BUILDX_CONFIG=/tmp/buildx-"+name,
+		"DOCKER_CONTEXT="+w.docker.DockerAddress(),
+	)
 	if err := cmd.Run(); err != nil {
 		return nil, nil, errors.Wrapf(err, "failed to create buildx instance %s", name)
 	}

tests/workers/docker.go

@@ -2,6 +2,7 @@ package workers
 
 import (
 	"context"
+	"os"
 	"os/exec"
 
 	"github.com/moby/buildkit/identity"
@@ -41,6 +42,7 @@ func (c dockerWorker) New(ctx context.Context, cfg *integration.BackendConfig) (
 		name,
 		"--docker", "host="+bk.DockerAddress(),
 	)
+	cmd.Env = append(os.Environ(), "BUILDX_CONFIG=/tmp/buildx-"+name)
 	if err := cmd.Run(); err != nil {
 		return bk, cl, errors.Wrapf(err, "failed to create buildx instance %s", name)
 	}

tests/workers/remote.go

@@ -2,6 +2,7 @@ package workers
 
 import (
 	"context"
+	"os"
 	"os/exec"
 
 	"github.com/moby/buildkit/identity"
@@ -41,6 +42,7 @@ func (w remoteWorker) New(ctx context.Context, cfg *integration.BackendConfig) (
 		"--driver=remote",
 		bk.Address(),
 	)
+	cmd.Env = append(os.Environ(), "BUILDX_CONFIG=/tmp/buildx-"+name)
 	if err := cmd.Run(); err != nil {
 		return nil, nil, errors.Wrapf(err, "failed to create buildx instance %s", name)
 	}