forked from containerd/containerd
-
Notifications
You must be signed in to change notification settings - Fork 0
/
main.go
160 lines (153 loc) · 3.78 KB
/
main.go
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
158
159
160
package main
import (
"flag"
"fmt"
"os"
"os/signal"
"path/filepath"
"syscall"
"github.com/docker/containerd/osutils"
"github.com/docker/docker/pkg/term"
)
func writeMessage(f *os.File, level string, err error) {
fmt.Fprintf(f, `{"level": "%s","msg": "%s"}`, level, err)
}
type controlMessage struct {
Type int
Width int
Height int
}
// containerd-shim is a small shim that sits in front of a runtime implementation
// that allows it to be repartented to init and handle reattach from the caller.
//
// the cwd of the shim should be the path to the state directory where the shim
// can locate fifos and other information.
// Arg0: id of the container
// Arg1: bundle path
// Arg2: runtime binary
func main() {
flag.Parse()
cwd, err := os.Getwd()
if err != nil {
panic(err)
}
f, err := os.OpenFile(filepath.Join(cwd, "shim-log.json"), os.O_CREATE|os.O_WRONLY|os.O_APPEND|os.O_SYNC, 0666)
if err != nil {
panic(err)
}
if err := start(f); err != nil {
// this means that the runtime failed starting the container and will have the
// proper error messages in the runtime log so we should to treat this as a
// shim failure because the sim executed properly
if err == errRuntime {
f.Close()
return
}
// log the error instead of writing to stderr because the shim will have
// /dev/null as it's stdio because it is supposed to be reparented to system
// init and will not have anyone to read from it
writeMessage(f, "error", err)
f.Close()
os.Exit(1)
}
}
func start(log *os.File) error {
// start handling signals as soon as possible so that things are properly reaped
// or if runtime exits before we hit the handler
signals := make(chan os.Signal, 2048)
signal.Notify(signals)
// set the shim as the subreaper for all orphaned processes created by the container
if err := osutils.SetSubreaper(1); err != nil {
return err
}
// open the exit pipe
f, err := os.OpenFile("exit", syscall.O_WRONLY, 0)
if err != nil {
return err
}
defer f.Close()
control, err := os.OpenFile("control", syscall.O_RDWR, 0)
if err != nil {
return err
}
defer control.Close()
p, err := newProcess(flag.Arg(0), flag.Arg(1), flag.Arg(2))
if err != nil {
return err
}
defer func() {
if err := p.Close(); err != nil {
writeMessage(log, "warn", err)
}
}()
if err := p.create(); err != nil {
p.delete()
return err
}
msgC := make(chan controlMessage, 32)
go func() {
for {
var m controlMessage
if _, err := fmt.Fscanf(control, "%d %d %d\n", &m.Type, &m.Width, &m.Height); err != nil {
continue
}
msgC <- m
}
}()
var exitShim bool
for {
select {
case s := <-signals:
switch s {
case syscall.SIGCHLD:
exits, _ := osutils.Reap(false)
for _, e := range exits {
// check to see if runtime is one of the processes that has exited
if e.Pid == p.pid() {
exitShim = true
writeInt("exitStatus", e.Status)
}
}
}
// runtime has exited so the shim can also exit
if exitShim {
// Let containerd take care of calling the runtime
// delete.
// This is needed to be done first in order to ensure
// that the call to Reap does not block until all
// children of the container have died if init was not
// started in its own PID namespace.
f.Close()
p.Wait()
return nil
}
case msg := <-msgC:
switch msg.Type {
case 0:
// close stdin
if p.stdinCloser != nil {
p.stdinCloser.Close()
}
case 1:
if p.console == nil {
continue
}
ws := term.Winsize{
Width: uint16(msg.Width),
Height: uint16(msg.Height),
}
term.SetWinsize(p.console.Fd(), &ws)
}
}
}
return nil
}
func writeInt(path string, i int) error {
f, err := os.Create(path)
if err != nil {
return err
}
defer f.Close()
_, err = fmt.Fprintf(f, "%d", i)
return err
}