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// Package hooks implements hook configuration and handling for CRI-O and libpod.
package hooks
import (
"context"
"fmt"
"path/filepath"
"sync"
rspec "github.com/opencontainers/runtime-spec/specs-go"
"github.com/pkg/errors"
current "github.com/projectatomic/libpod/pkg/hooks/1.0.0"
"golang.org/x/text/collate"
"golang.org/x/text/language"
)
// 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
language language.Tag
lock sync.Mutex
}
type namedHook struct {
name string
hook *current.Hook
}
type namedHooks []*namedHook
// 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 delagating to the OCI runtime. See
// Hooks() for more information.
func New(ctx context.Context, directories []string, extensionStages []string, lang language.Tag) (manager *Manager, err error) {
manager = &Manager{
hooks: map[string]*current.Hook{},
directories: directories,
extensionStages: extensionStages,
language: lang,
}
for _, dir := range directories {
err = ReadDir(dir, manager.extensionStages, manager.hooks)
if err != nil {
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 the extensionStages slice was set when initializing the Manager,
// matching hooks requesting those stages will be returned in the
// extensionStages map. This takes precedence over their inclusion in
// the OCI configuration. For example:
//
// manager, err := New(ctx, []string{DefaultDir}, []string{"poststop"}, lang)
// extensionStages, err := manager.Hooks(config, annotations, hasBindMounts)
//
// will have any matching post-stop hooks in extensionStages and will
// not insert them into config.Hooks.Poststop.
func (m *Manager) Hooks(config *rspec.Spec, annotations map[string]string, hasBindMounts bool) (extensionStages map[string][]rspec.Hook, err error) {
hooks := m.namedHooks()
collator := collate.New(m.language, collate.IgnoreCase, collate.IgnoreWidth)
collator.Sort(namedHooks(hooks))
localStages := map[string]bool{} // stages destined for extensionStages
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 extensionStages, errors.Wrapf(err, "matching hook %q", namedHook.name)
}
if match {
if config.Hooks == nil {
config.Hooks = &rspec.Hooks{}
}
for _, stage := range namedHook.hook.Stages {
if _, ok := localStages[stage]; ok {
if extensionStages == nil {
extensionStages = map[string][]rspec.Hook{}
}
extensionStages[stage] = append(extensionStages[stage], namedHook.hook.Hook)
} else {
switch stage {
case "prestart":
config.Hooks.Prestart = append(config.Hooks.Prestart, 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)
default:
return extensionStages, fmt.Errorf("hook %q: unknown stage %q", namedHook.name, stage)
}
}
}
}
}
return extensionStages, nil
}
// remove remove a hook by name.
func (m *Manager) remove(hook string) (ok bool) {
m.lock.Lock()
defer m.lock.Unlock()
_, ok = m.hooks[hook]
if ok {
delete(m.hooks, hook)
}
return ok
}
// add adds a hook by path
func (m *Manager) add(path string) (err error) {
m.lock.Lock()
defer m.lock.Unlock()
hook, err := Read(path, m.extensionStages)
if err != nil {
return err
}
m.hooks[filepath.Base(path)] = hook
return nil
}
// Len is part of the collate.Lister interface.
func (hooks namedHooks) Len() int {
return len(hooks)
}
// Swap is part of the collate.Lister interface.
func (hooks namedHooks) Swap(i, j int) {
hooks[i], hooks[j] = hooks[j], hooks[i]
}
// Bytes is part of the collate.Lister interface.
func (hooks namedHooks) Bytes(i int) []byte {
return []byte(hooks[i].name)
}
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