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
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
package main
import (
"fmt"
"os"
"os/exec"
"os/signal"
"path/filepath"
"strconv"
"syscall"
"time"
"github.com/sirupsen/logrus"
"gitlab.com/gitlab-org/gitaly/v14/internal/bootstrap"
"gitlab.com/gitlab-org/gitaly/v14/internal/helper/env"
"gitlab.com/gitlab-org/gitaly/v14/internal/log"
"gitlab.com/gitlab-org/gitaly/v14/internal/ps"
"golang.org/x/sys/unix"
)
const (
envJSONLogging = "WRAPPER_JSON_LOGGING"
)
func main() {
if jsonLogging() {
logrus.SetFormatter(&logrus.JSONFormatter{TimestampFormat: log.LogTimestampFormat})
}
if len(os.Args) < 2 {
logrus.Fatalf("usage: %s forking_binary [args]", os.Args[0])
}
gitalyBin, gitalyArgs := os.Args[1], os.Args[2:]
log := logrus.WithField("wrapper", os.Getpid())
log.Info("Wrapper started")
if pidFile() == "" {
log.Fatalf("missing pid file ENV variable %q", bootstrap.EnvPidFile)
}
log.WithField("pid_file", pidFile()).Info("finding gitaly")
gitaly, err := findGitaly()
if err != nil && !isRecoverable(err) {
log.WithError(err).Fatal("find gitaly")
} else if err != nil {
log.WithError(err).Error("find gitaly")
}
if gitaly != nil && isGitaly(gitaly, gitalyBin) {
log.Info("adopting a process")
} else {
log.Info("spawning a process")
proc, err := spawnGitaly(gitalyBin, gitalyArgs)
if err != nil {
log.WithError(err).Fatal("spawn gitaly")
}
gitaly = proc
}
log = log.WithField("gitaly", gitaly.Pid)
log.Info("monitoring gitaly")
forwardSignals(gitaly, log)
// wait
for isAlive(gitaly) {
time.Sleep(1 * time.Second)
}
log.Error("wrapper for gitaly shutting down")
}
func isRecoverable(err error) bool {
_, isNumError := err.(*strconv.NumError)
return os.IsNotExist(err) || isNumError
}
func findGitaly() (*os.Process, error) {
pid, err := getPid()
if err != nil {
return nil, err
}
// os.FindProcess on unix do not return an error if the process does not exist
gitaly, err := os.FindProcess(pid)
if err != nil {
return nil, err
}
if isAlive(gitaly) {
return gitaly, nil
}
return nil, nil
}
func spawnGitaly(bin string, args []string) (*os.Process, error) {
cmd := exec.Command(bin, args...)
cmd.Env = append(os.Environ(), fmt.Sprintf("%s=true", bootstrap.EnvUpgradesEnabled))
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
if err := cmd.Start(); err != nil {
return nil, err
}
// This cmd.Wait() is crucial. Without it we cannot detect if the command we just spawned has crashed.
go cmd.Wait()
return cmd.Process, nil
}
func isRuntimeSig(s os.Signal) bool {
return s == unix.SIGURG
}
func forwardSignals(gitaly *os.Process, log *logrus.Entry) {
sigs := make(chan os.Signal, 1)
go func() {
for sig := range sigs {
// In go1.14+, the go runtime issues SIGURG as an interrupt
// to support pre-emptible system calls on Linux. We ignore
// this signal since it's not relevant to the Gitaly process.
if isRuntimeSig(sig) {
continue
}
log.WithField("signal", sig).Warning("forwarding signal")
if err := gitaly.Signal(sig); err != nil {
log.WithField("signal", sig).WithError(err).Error("can't forward the signal")
}
}
}()
signal.Notify(sigs)
}
func getPid() (int, error) {
data, err := os.ReadFile(pidFile())
if err != nil {
return 0, err
}
return strconv.Atoi(string(data))
}
func isAlive(p *os.Process) bool {
// After p exits, and after it gets reaped, this p.Signal will fail. It is crucial that p gets reaped.
// If p was spawned by the current process, it will get reaped from a goroutine that does cmd.Wait().
// If p was spawned by someone else we rely on them to reap it, or on p to become an orphan.
// In the orphan case p should get reaped by the OS (PID 1).
return p.Signal(syscall.Signal(0)) == nil
}
func isGitaly(p *os.Process, gitalyBin string) bool {
command, err := ps.Comm(p.Pid)
if err != nil {
return false
}
if filepath.Base(command) == filepath.Base(gitalyBin) {
return true
}
return false
}
func pidFile() string {
return os.Getenv(bootstrap.EnvPidFile)
}
func jsonLogging() bool {
enabled, _ := env.GetBool(envJSONLogging, false)
return enabled
}
|
