add restic integration for doing pod volume backups/restores

Signed-off-by: Steve Kriss <steve@heptio.com>

pkg/restic/command.go

@@ -0,0 +1,72 @@
+/*
+Copyright 2018 the Heptio Ark contributors.
+
+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 restic
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+// Command represents a restic command.
+type Command struct {
+	BaseName     string
+	Command      string
+	RepoPrefix   string
+	Repo         string
+	PasswordFile string
+	Args         []string
+	ExtraFlags   []string
+}
+
+// StringSlice returns the command as a slice of strings.
+func (c *Command) StringSlice() []string {
+	var res []string
+	if c.BaseName != "" {
+		res = append(res, c.BaseName)
+	} else {
+		res = append(res, "/restic")
+	}
+
+	res = append(res, c.Command, repoFlag(c.RepoPrefix, c.Repo))
+	if c.PasswordFile != "" {
+		res = append(res, passwordFlag(c.PasswordFile))
+	}
+	res = append(res, c.Args...)
+	res = append(res, c.ExtraFlags...)
+
+	return res
+}
+
+// String returns the command as a string.
+func (c *Command) String() string {
+	return strings.Join(c.StringSlice(), " ")
+}
+
+// Cmd returns an exec.Cmd for the command.
+func (c *Command) Cmd() *exec.Cmd {
+	parts := c.StringSlice()
+	return exec.Command(parts[0], parts[1:]...)
+}
+
+func repoFlag(prefix, repo string) string {
+	return fmt.Sprintf("--repo=%s/%s", prefix, repo)
+}
+
+func passwordFlag(file string) string {
+	return fmt.Sprintf("--password-file=%s", file)
+}