cleanup: move pkg/ to internal/

The internal/ directory in Go has a special meaning, and indicates that
those packages are not meant for external consumption. Ceph-CSI does
provide public APIs for other projects to consume. There is no plan to
keep the API of the internally used packages stable.

Closes: #903
Signed-off-by: Niels de Vos <ndevos@redhat.com>

internal/util/pidlimit_test.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2019 ceph-csi authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"os"
+	"testing"
+)
+
+// minimal test to check if GetPIDLimit() returns an int
+// changing the limit require root permissions, not tested
+func TestGetPIDLimit(t *testing.T) {
+	runTest := os.Getenv("CEPH_CSI_RUN_ALL_TESTS")
+	if runTest == "" {
+		t.Skip("not running test that requires root permissions and cgroup support")
+	}
+
+	limit, err := GetPIDLimit()
+
+	if err != nil {
+		t.Errorf("no error should be returned, got: %v", err)
+	}
+	if limit == 0 {
+		t.Error("a PID limit of 0 is invalid")
+	}
+
+	// this is expected to fail when not run as root
+	err = SetPIDLimit(4096)
+	if err != nil {
+		t.Log("failed to set PID limit, are you running as root?")
+	} else {
+		// in case it worked, reset to the previous value
+		err = SetPIDLimit(limit)
+		if err != nil {
+			t.Logf("failed to reset PID to original limit %d", limit)
+		}
+	}
+}