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hook-injector.go
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hook-injector.go
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/*
Copyright The containerd 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 main
import (
"context"
"flag"
"fmt"
"os"
"strings"
"github.com/containers/common/pkg/hooks"
rspec "github.com/opencontainers/runtime-spec/specs-go"
"github.com/sirupsen/logrus"
"sigs.k8s.io/yaml"
"github.com/containerd/nri/pkg/api"
"github.com/containerd/nri/pkg/stub"
)
var (
log *logrus.Logger
verbose bool
)
type plugin struct {
stub stub.Stub
mgr *hooks.Manager
}
func (p *plugin) CreateContainer(_ context.Context, pod *api.PodSandbox, container *api.Container) (*api.ContainerAdjustment, []*api.ContainerUpdate, error) {
ctrName := containerName(pod, container)
if verbose {
dump("CreateContainer", "pod", pod, "container", container)
}
annotations := map[string]string{}
for k, v := range container.Annotations {
annotations[k] = v
}
for k, v := range pod.Annotations {
annotations[k] = v
}
hasBindMounts := len(container.Mounts) > 0
spec := &rspec.Spec{
Process: &rspec.Process{
Args: container.Args,
},
}
if verbose {
dump(ctrName, "OCI Spec", spec)
dump(ctrName, "Annotations", annotations)
}
if _, err := p.mgr.Hooks(spec, annotations, hasBindMounts); err != nil {
log.Errorf("%s: failed to generate hooks: %v", ctrName, err)
return nil, nil, fmt.Errorf("hook generation failed: %w", err)
}
if spec.Hooks == nil {
log.Infof("%s: no hooks to inject, ignoring", ctrName)
return nil, nil, nil
}
adjust := &api.ContainerAdjustment{}
adjust.AddHooks(api.FromOCIHooks(spec.Hooks))
if verbose {
dump(ctrName, "ContainerAdjustment", adjust)
} else {
log.Infof("%s: OCI hooks injected", ctrName)
}
return adjust, nil, nil
}
// Construct a container name for log messages.
func containerName(pod *api.PodSandbox, container *api.Container) string {
if pod != nil {
return pod.Name + "/" + container.Name
}
return container.Name
}
// Dump one or more objects, with an optional global prefix and per-object tags.
func dump(args ...interface{}) {
var (
prefix string
idx int
)
if len(args)&0x1 == 1 {
prefix = args[0].(string)
idx++
}
for ; idx < len(args)-1; idx += 2 {
tag, obj := args[idx], args[idx+1]
msg, err := yaml.Marshal(obj)
if err != nil {
log.Infof("%s: %s: failed to dump object: %v", prefix, tag, err)
continue
}
if prefix != "" {
log.Infof("%s: %s:", prefix, tag)
for _, line := range strings.Split(strings.TrimSpace(string(msg)), "\n") {
log.Infof("%s: %s", prefix, line)
}
} else {
log.Infof("%s:", tag)
for _, line := range strings.Split(strings.TrimSpace(string(msg)), "\n") {
log.Infof(" %s", line)
}
}
}
}
func main() {
var (
pluginName string
pluginIdx string
disableWatch bool
opts []stub.Option
mgr *hooks.Manager
err error
)
log = logrus.StandardLogger()
log.SetFormatter(&logrus.TextFormatter{
PadLevelText: true,
})
flag.StringVar(&pluginName, "name", "", "plugin name to register to NRI")
flag.StringVar(&pluginIdx, "idx", "", "plugin index to register to NRI")
flag.BoolVar(&verbose, "verbose", false, "enable (more) verbose logging")
flag.BoolVar(&disableWatch, "disableWatch", false, "disable watching hook directories for new hooks")
flag.Parse()
if pluginName != "" {
opts = append(opts, stub.WithPluginName(pluginName))
}
if pluginIdx != "" {
opts = append(opts, stub.WithPluginIdx(pluginIdx))
}
p := &plugin{}
if p.stub, err = stub.New(p, opts...); err != nil {
log.Errorf("failed to create plugin stub: %v", err)
os.Exit(1)
}
ctx := context.Background()
dirs := []string{hooks.DefaultDir, hooks.OverrideDir}
mgr, err = hooks.New(ctx, dirs, []string{})
if err != nil {
log.Errorf("failed to set up hook manager: %v", err)
os.Exit(1)
}
p.mgr = mgr
if !disableWatch {
for _, dir := range dirs {
if err = os.MkdirAll(dir, 0755); err != nil {
log.Errorf("failed to create directory %q: %v", dir, err)
os.Exit(1)
}
}
sync := make(chan error, 2)
go mgr.Monitor(ctx, sync)
err = <-sync
if err != nil {
log.Errorf("failed to monitor hook directories: %v", err)
os.Exit(1)
}
log.Infof("watching directories %q for new changes", strings.Join(dirs, " "))
}
err = p.stub.Run(ctx)
if err != nil {
log.Errorf("plugin exited with error %v", err)
os.Exit(1)
}
}