vbatts/containerd
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Remove dep on larger packages

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This removes most of the deps on the larger packages for the shim and
reduces the binary size and memory footprint from a 7.1mb binary to a
2.6mb binary.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
This commit is contained in:
Michael Crosby 2016-04-04 11:23:40 -07:00
parent 96034177f9
commit 6f18acda73
5 changed files with 122 additions and 41 deletions
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30
containerd-shim/main.go
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@ -8,11 +8,14 @@ import (
"path/filepath"
"syscall"
"github.com/Sirupsen/logrus"
"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)
}
// 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.
//
@ -28,9 +31,7 @@ func main() {
if err != nil {
panic(err)
}
logrus.SetOutput(f)
logrus.SetFormatter(&logrus.JSONFormatter{})
if err := start(); err != nil {
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
@ -41,13 +42,13 @@ func main() {
// 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
logrus.Error(err)
writeMessage(f, "error", err)
f.Close()
os.Exit(1)
}
}
func start() error {
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)
@ -73,7 +74,7 @@ func start() error {
}
defer func() {
if err := p.Close(); err != nil {
logrus.Warn(err)
writeMessage(log, "warn", err)
}
}()
if err := p.start(); err != nil {
@ -84,7 +85,7 @@ func start() error {
for {
var msg, w, h int
if _, err := fmt.Fscanf(control, "%d %d %d\n", &msg, &w, &h); err != nil {
logrus.Warn(err)
continue
}
switch msg {
case 0:
@ -108,21 +109,12 @@ func start() error {
for s := range signals {
switch s {
case syscall.SIGCHLD:
exits, err := osutils.Reap()
if err != nil {
logrus.Warn(err)
}
exits, _ := osutils.Reap()
for _, e := range exits {
// check to see if runtime is one of the processes that has exited
if e.Pid == p.pid() {
exitShim = true
logrus.WithFields(logrus.Fields{
"pid": e.Pid,
"status": e.Status,
}).Info("shim: runtime exited")
if err := writeInt("exitStatus", e.Status); err != nil {
logrus.WithFields(logrus.Fields{"status": e.Status}).Warn(err)
}
writeInt("exitStatus", e.Status)
}
}
}