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/csiconfig.go

@@ -0,0 +1,74 @@
+/*
+Copyright 2019 The 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 (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"strings"
+)
+
+/*
+Mons returns a comma separated MON list from the csi config for the given clusterID
+Expected JSON structure in the passed in config file is,
+[
+	{
+		"clusterID": "<cluster-id>",
+		"monitors":
+			[
+				"<monitor-value>",
+				"<monitor-value>",
+				...
+			]
+	},
+	...
+]
+*/
+
+// clusterInfo strongly typed JSON spec for the above JSON structure
+type clusterInfo struct {
+	ClusterID string   `json:"clusterID"`
+	Monitors  []string `json:"monitors"`
+}
+
+func Mons(pathToConfig, clusterID string) (string, error) {
+	var config []clusterInfo
+
+	// #nosec
+	content, err := ioutil.ReadFile(pathToConfig)
+	if err != nil {
+		err = fmt.Errorf("error fetching configuration for cluster ID (%s). (%s)", clusterID, err)
+		return "", err
+	}
+
+	err = json.Unmarshal(content, &config)
+	if err != nil {
+		return "", fmt.Errorf("unmarshal failed: %v. raw buffer response: %s",
+			err, string(content))
+	}
+
+	for _, cluster := range config {
+		if cluster.ClusterID == clusterID {
+			if len(cluster.Monitors) == 0 {
+				return "", fmt.Errorf("empty monitor list for cluster ID (%s) in config", clusterID)
+			}
+			return strings.Join(cluster.Monitors, ","), nil
+		}
+	}
+	return "", fmt.Errorf("missing configuration for cluster ID (%s)", clusterID)
+}