1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
|
// Copyright 2018 The gVisor 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 cmd
import (
"context"
"encoding/json"
"fmt"
"io/ioutil"
"math/rand"
"os"
"path/filepath"
"syscall"
"flag"
"github.com/google/subcommands"
specs "github.com/opencontainers/runtime-spec/specs-go"
"gvisor.googlesource.com/gvisor/pkg/log"
"gvisor.googlesource.com/gvisor/runsc/boot"
"gvisor.googlesource.com/gvisor/runsc/container"
"gvisor.googlesource.com/gvisor/runsc/specutils"
)
// Do implements subcommands.Command for the "do" command. It sets up a simple
// sandbox and executes the command inside it. See Usage() for more details.
type Do struct {
root string
cwd string
}
// Name implements subcommands.Command.Name.
func (*Do) Name() string {
return "do"
}
// Synopsis implements subcommands.Command.Synopsis.
func (*Do) Synopsis() string {
return "Simplistic way to execute a command inside the sandbox. It's to be used for testing only."
}
// Usage implements subcommands.Command.Usage.
func (*Do) Usage() string {
return `do [flags] <cmd> - runs a command.
This command starts a sandbox with host filesystem mounted inside as readonly,
with a writable tmpfs overlay on top of it. The given command is executed inside
the sandbox. It's to be used to quickly test applications without having to
install or run docker. It doesn't give nearly as many options and it's to be
used for testing only.
`
}
// SetFlags implements subcommands.Command.SetFlags.
func (c *Do) SetFlags(f *flag.FlagSet) {
f.StringVar(&c.root, "root", "/", `path to the root directory, defaults to "/"`)
f.StringVar(&c.cwd, "cwd", ".", `path to the current directory, defaults to the current directory`)
}
// Execute implements subcommands.Command.Execute.
func (c *Do) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
if len(f.Args()) == 0 {
c.Usage()
return subcommands.ExitUsageError
}
conf := args[0].(*boot.Config)
waitStatus := args[1].(*syscall.WaitStatus)
// Map the entire host file system, but make it readonly with a writable
// overlay on top (ignore --overlay option).
conf.Overlay = true
hostname, err := os.Hostname()
if err != nil {
Fatalf("Error to retrieve hostname: %v", err)
}
absRoot, err := resolvePath(c.root)
if err != nil {
Fatalf("Error resolving root: %v", err)
}
absCwd, err := resolvePath(c.cwd)
if err != nil {
Fatalf("Error resolving current directory: %v", err)
}
spec := &specs.Spec{
Root: &specs.Root{
Path: absRoot,
Readonly: true,
},
Process: &specs.Process{
Cwd: absCwd,
Args: f.Args(),
Env: os.Environ(),
Capabilities: specutils.AllCapabilities(),
},
Hostname: hostname,
}
specutils.LogSpec(spec)
out, err := json.Marshal(spec)
if err != nil {
Fatalf("Error to marshal spec: %v", err)
}
tmpDir, err := ioutil.TempDir("", "runsc-do")
if err != nil {
Fatalf("Error to create tmp dir: %v", err)
}
defer os.RemoveAll(tmpDir)
log.Infof("Changing configuration RootDir to %q", tmpDir)
conf.RootDir = tmpDir
cfgPath := filepath.Join(tmpDir, "config.json")
if err := ioutil.WriteFile(cfgPath, out, 0755); err != nil {
Fatalf("Error write spec: %v", err)
}
// No network support yet.
conf.Network = boot.NetworkNone
id := fmt.Sprintf("runcs-do-%06d", rand.Int31n(1000000))
ws, err := container.Run(id, spec, conf, tmpDir, "", "", "")
if err != nil {
Fatalf("running container: %v", err)
}
*waitStatus = ws
return subcommands.ExitSuccess
}
func resolvePath(path string) (string, error) {
var err error
path, err = filepath.Abs(path)
if err != nil {
return "", fmt.Errorf("resolving %q: %v", path, err)
}
path = filepath.Clean(path)
if err := syscall.Access(path, 0); err != nil {
return "", fmt.Errorf("unable to access %q: %v", path, err)
}
return path, nil
}
|
