integration: ensurePlugin: disable go modules when building plugin

    === RUN   TestServicePlugin
        plugin_test.go:42: assertion failed: error is not nil: error building basic plugin bin: no required module provides package github.com/docker/docker/testutil/fixtures/plugin/basic: go.mod file not found in current directory or any parent directory; see 'go help modules'
            : exit status 1

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 7070df3a3e4f668c10b7c8527b15e93926214244)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

integration/plugin/logging/helpers_test.go

@@ -31,7 +31,7 @@ func ensurePlugin(t *testing.T, name string) string {
 	}
 
 	cmd := exec.Command(goBin, "build", "-o", installPath, "./"+filepath.Join("cmd", name))
-	cmd.Env = append(os.Environ(), "CGO_ENABLED=0")
+	cmd.Env = append(os.Environ(), "CGO_ENABLED=0", "GO111MODULE=off")
 	if out, err := cmd.CombinedOutput(); err != nil {
 		t.Fatal(errors.Wrapf(err, "error building basic plugin bin: %s", string(out)))
 	}

integration/plugin/volumes/helpers_test.go

@@ -36,7 +36,7 @@ func ensurePlugin(t *testing.T, name string) string {
 	assert.NilError(t, err)
 
 	cmd := exec.Command(goBin, "build", "-o", installPath, "./"+filepath.Join("cmd", name))
-	cmd.Env = append(os.Environ(), "CGO_ENABLED=0")
+	cmd.Env = append(os.Environ(), "CGO_ENABLED=0", "GO111MODULE=off")
 	if out, err := cmd.CombinedOutput(); err != nil {
 		t.Fatal(errors.Wrapf(err, "error building basic plugin bin: %s", string(out)))
 	}

testutil/fixtures/plugin/plugin.go

@@ -222,7 +222,7 @@ func ensureBasicPluginBin() (string, error) {
 	installPath := filepath.Join(os.Getenv("GOPATH"), "bin", name)
 	sourcePath := filepath.Join("github.com", "docker", "docker", "testutil", "fixtures", "plugin", "basic")
 	cmd := exec.Command(goBin, "build", "-o", installPath, sourcePath)
-	cmd.Env = append(os.Environ(), "CGO_ENABLED=0")
+	cmd.Env = append(os.Environ(), "CGO_ENABLED=0", "GO111MODULE=off")
 	if out, err := cmd.CombinedOutput(); err != nil {
 		return "", errors.Wrapf(err, "error building basic plugin bin: %s", string(out))
 	}