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// Package hooks implements hook configuration and handling for CRI-O and libpod.
package hooks
import (
"context"
"errors"
"fmt"
"os"
"sort"
"strings"
"sync"
current "github.com/containers/common/pkg/hooks/1.0.0"
rspec "github.com/opencontainers/runtime-spec/specs-go"
"github.com/sirupsen/logrus"
)
// Version is the current hook configuration version.
const Version = current.Version
const (
// DefaultDir is the default directory containing system hook configuration files.
DefaultDir = "/usr/share/containers/oci/hooks.d"
// OverrideDir is the directory for hook configuration files overriding the default entries.
OverrideDir = "/etc/containers/oci/hooks.d"
)
// Manager provides an opaque interface for managing CRI-O hooks.
type Manager struct {
hooks map[string]*current.Hook
directories []string
extensionStages []string
lock sync.Mutex
}
type namedHook struct {
name string
hook *current.Hook
}
// New creates a new hook manager. Directories are ordered by
// increasing preference (hook configurations in later directories
// override configurations with the same filename from earlier
// directories).
//
// extensionStages allows callers to add additional stages beyond
// those specified in the OCI Runtime Specification and to control
// OCI-defined stages instead of delegating to the OCI runtime. See
// Hooks() for more information.
func New(_ context.Context, directories []string, extensionStages []string) (manager *Manager, err error) {
manager = &Manager{
hooks: map[string]*current.Hook{},
directories: directories,
extensionStages: extensionStages,
}
for _, dir := range directories {
err = ReadDir(dir, manager.extensionStages, manager.hooks)
if err != nil && !errors.Is(err, os.ErrNotExist) {
return nil, err
}
}
return manager, nil
}
// filenames returns sorted hook entries.
func (m *Manager) namedHooks() (hooks []*namedHook) {
m.lock.Lock()
defer m.lock.Unlock()
hooks = make([]*namedHook, len(m.hooks))
i := 0
for name, hook := range m.hooks {
hooks[i] = &namedHook{
name: name,
hook: hook,
}
i++
}
return hooks
}
// Hooks injects OCI runtime hooks for a given container configuration.
//
// If extensionStages was set when initializing the Manager,
// matching hooks requesting those stages will be returned in
// extensionStageHooks. This takes precedence over their inclusion in
// the OCI configuration. For example:
//
// manager, err := New(ctx, []string{DefaultDir}, []string{"poststop"})
// extensionStageHooks, err := manager.Hooks(config, annotations, hasBindMounts)
//
// will have any matching post-stop hooks in extensionStageHooks and
// will not insert them into config.Hooks.Poststop.
func (m *Manager) Hooks(config *rspec.Spec, annotations map[string]string, hasBindMounts bool) (extensionStageHooks map[string][]rspec.Hook, err error) {
hooks := m.namedHooks()
sort.Slice(hooks, func(i, j int) bool { return strings.ToLower(hooks[i].name) < strings.ToLower(hooks[j].name) })
localStages := map[string]bool{} // stages destined for extensionStageHooks
for _, stage := range m.extensionStages {
localStages[stage] = true
}
for _, namedHook := range hooks {
match, err := namedHook.hook.When.Match(config, annotations, hasBindMounts)
if err != nil {
return extensionStageHooks, fmt.Errorf("matching hook %q: %w", namedHook.name, err)
}
if match {
logrus.Debugf("hook %s matched; adding to stages %v", namedHook.name, namedHook.hook.Stages)
if config.Hooks == nil {
config.Hooks = &rspec.Hooks{}
}
for _, stage := range namedHook.hook.Stages {
if _, ok := localStages[stage]; ok {
if extensionStageHooks == nil {
extensionStageHooks = map[string][]rspec.Hook{}
}
extensionStageHooks[stage] = append(extensionStageHooks[stage], namedHook.hook.Hook)
} else {
switch stage {
case "createContainer":
config.Hooks.CreateContainer = append(config.Hooks.CreateContainer, namedHook.hook.Hook)
case "createRuntime", "prestart":
config.Hooks.CreateRuntime = append(config.Hooks.CreateRuntime, namedHook.hook.Hook)
case "poststart":
config.Hooks.Poststart = append(config.Hooks.Poststart, namedHook.hook.Hook)
case "poststop":
config.Hooks.Poststop = append(config.Hooks.Poststop, namedHook.hook.Hook)
case "startContainer":
config.Hooks.StartContainer = append(config.Hooks.StartContainer, namedHook.hook.Hook)
default:
return extensionStageHooks, fmt.Errorf("hook %q: unknown stage %q", namedHook.name, stage)
}
}
}
} else {
logrus.Debugf("hook %s did not match", namedHook.name)
}
}
return extensionStageHooks, nil
}
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