added cephfs/cephfsconf.go: generates ceph config and keyring

pkg/cephfs/cephconf.go

@@ -0,0 +1,104 @@
+/*
+Copyright 2018 The Kubernetes 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 cephfs
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"text/template"
+)
+
+const cephConfig = `[global]
+mon_host = {{.Monitors}}
+auth_cluster_required = cephx
+auth_service_required = cephx
+auth_client_required = cephx
+`
+
+const cephKeyring = `[client.{{.User}}]
+key = {{.Key}}
+caps mds = "allow {{perms .ReadOnly}} path={{.RootPath}}"
+caps mon = "allow r"
+caps osd = "allow {{perms .ReadOnly}}"
+`
+
+const (
+	cephConfigRoot         = "/etc/ceph"
+	cephConfigFileName     = "ceph.conf"
+	cephKeyringFileNameFmt = "ceph.client.%s.keyring"
+)
+
+var (
+	cephConfigTempl  *template.Template
+	cephKeyringTempl *template.Template
+)
+
+func init() {
+	fm := map[string]interface{}{
+		"perms": func(readOnly bool) string {
+			if readOnly {
+				return "r"
+			}
+
+			return "rw"
+		},
+	}
+
+	cephConfigTempl = template.Must(template.New("config").Parse(cephConfig))
+	cephKeyringTempl = template.Must(template.New("keyring").Funcs(fm).Parse(cephKeyring))
+}
+
+type cephConfigWriter interface {
+	writeToFile() error
+}
+
+type cephConfigData struct {
+	Monitors string
+}
+
+func writeCephTemplate(fileName string, m os.FileMode, t *template.Template, data interface{}) error {
+	if err := os.MkdirAll(cephConfigRoot, 0755); err != nil {
+		return err
+	}
+
+	f, err := os.OpenFile(path.Join(cephConfigRoot, fileName), os.O_CREATE|os.O_EXCL|os.O_WRONLY, m)
+	if err != nil {
+		if os.IsExist(err) {
+			return nil
+		}
+		return err
+	}
+
+	defer f.Close()
+
+	return t.Execute(f, data)
+}
+
+func (d *cephConfigData) writeToFile() error {
+	return writeCephTemplate(cephConfigFileName, 0640, cephConfigTempl, d)
+}
+
+type cephKeyringData struct {
+	User, Key string
+	RootPath  string
+	ReadOnly  bool
+}
+
+func (d *cephKeyringData) writeToFile() error {
+	return writeCephTemplate(fmt.Sprintf(cephKeyringFileNameFmt, d.User), 0600, cephKeyringTempl, d)
+}