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// 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 container
import (
"bytes"
"encoding/json"
"fmt"
"os/exec"
"path/filepath"
"strings"
"time"
specs "github.com/opencontainers/runtime-spec/specs-go"
"gvisor.dev/gvisor/pkg/log"
)
// This file implements hooks as defined in OCI spec:
// https://github.com/opencontainers/runtime-spec/blob/master/config.md#toc22
//
// "hooks":{
// "prestart":[{
// "path":"/usr/bin/dockerd",
// "args":[
// "libnetwork-setkey", "arg2",
// ]
// }]
// },
// executeHooksBestEffort executes hooks and logs warning in case they fail.
// Runs all hooks, always.
func executeHooksBestEffort(hooks []specs.Hook, s specs.State) {
for _, h := range hooks {
if err := executeHook(h, s); err != nil {
log.Warningf("Failure to execute hook %+v, err: %v", h, err)
}
}
}
// executeHooks executes hooks until the first one fails or they all execute.
func executeHooks(hooks []specs.Hook, s specs.State) error {
for _, h := range hooks {
if err := executeHook(h, s); err != nil {
return err
}
}
return nil
}
func executeHook(h specs.Hook, s specs.State) error {
log.Debugf("Executing hook %+v, state: %+v", h, s)
if strings.TrimSpace(h.Path) == "" {
return fmt.Errorf("empty path for hook")
}
if !filepath.IsAbs(h.Path) {
return fmt.Errorf("path for hook is not absolute: %q", h.Path)
}
// Don't invoke nvidia-container-runtime-hook at prestart, which may be
// configured by e.g. Docker's --gpus flag, since
// nvidia-container-runtime-hook doesn't understand gVisor's bifurcation
// between sentry and application filesystems.
if strings.HasSuffix(h.Path, "/nvidia-container-runtime-hook") {
log.Infof("Skipping nvidia-container-runtime-hook")
return nil
}
b, err := json.Marshal(s)
if err != nil {
return err
}
var stdout, stderr bytes.Buffer
cmd := exec.Cmd{
Path: h.Path,
Args: h.Args,
Env: h.Env,
Stdin: bytes.NewReader(b),
Stdout: &stdout,
Stderr: &stderr,
}
if err := cmd.Start(); err != nil {
return err
}
c := make(chan error, 1)
go func() {
c <- cmd.Wait()
}()
var timer <-chan time.Time
if h.Timeout != nil {
timer = time.After(time.Duration(*h.Timeout) * time.Second)
}
select {
case err := <-c:
if err != nil {
return fmt.Errorf("failure executing hook %q, err: %v\nstdout: %s\nstderr: %s", h.Path, err, stdout.String(), stderr.String())
}
case <-timer:
_ = cmd.Process.Kill()
_ = cmd.Wait()
return fmt.Errorf("timeout executing hook %q\nstdout: %s\nstderr: %s", h.Path, stdout.String(), stderr.String())
}
log.Debugf("Execute hook %q success!", h.Path)
return nil
}
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