automation-tests/storage/containers.go

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package storage
import (
"errors"
"fmt"
"os"
"path/filepath"
"sync"
"time"
"github.com/containers/storage/pkg/idtools"
"github.com/containers/storage/pkg/ioutils"
"github.com/containers/storage/pkg/stringid"
"github.com/containers/storage/pkg/truncindex"
digest "github.com/opencontainers/go-digest"
)
// A Container is a reference to a read-write layer with metadata.
type Container struct {
// ID is either one which was specified at create-time, or a random
// value which was generated by the library.
ID string `json:"id"`
// Names is an optional set of user-defined convenience values. The
// container can be referred to by its ID or any of its names. Names
// are unique among containers.
Names []string `json:"names,omitempty"`
// ImageID is the ID of the image which was used to create the container.
ImageID string `json:"image"`
// LayerID is the ID of the read-write layer for the container itself.
// It is assumed that the image's top layer is the parent of the container's
// read-write layer.
LayerID string `json:"layer"`
// Metadata is data we keep for the convenience of the caller. It is not
// expected to be large, since it is kept in memory.
Metadata string `json:"metadata,omitempty"`
// BigDataNames is a list of names of data items that we keep for the
// convenience of the caller. They can be large, and are only in
// memory when being read from or written to disk.
BigDataNames []string `json:"big-data-names,omitempty"`
// BigDataSizes maps the names in BigDataNames to the sizes of the data
// that has been stored, if they're known.
BigDataSizes map[string]int64 `json:"big-data-sizes,omitempty"`
// BigDataDigests maps the names in BigDataNames to the digests of the
// data that has been stored, if they're known.
BigDataDigests map[string]digest.Digest `json:"big-data-digests,omitempty"`
// Created is the datestamp for when this container was created. Older
// versions of the library did not track this information, so callers
// will likely want to use the IsZero() method to verify that a value
// is set before using it.
Created time.Time `json:"created,omitempty"`
// UIDMap and GIDMap are used for setting up a container's root
// filesystem for use inside of a user namespace where UID mapping is
// being used.
UIDMap []idtools.IDMap `json:"uidmap,omitempty"`
GIDMap []idtools.IDMap `json:"gidmap,omitempty"`
Flags map[string]interface{} `json:"flags,omitempty"`
}
// rwContainerStore provides bookkeeping for information about Containers.
type rwContainerStore interface {
metadataStore
containerBigDataStore
flaggableStore
// startWriting makes sure the store is fresh, and locks it for writing.
// If this succeeds, the caller MUST call stopWriting().
startWriting() error
// stopWriting releases locks obtained by startWriting.
stopWriting()
// startReading makes sure the store is fresh, and locks it for reading.
// If this succeeds, the caller MUST call stopReading().
startReading() error
// stopReading releases locks obtained by startReading.
stopReading()
// Touch records, for others sharing the lock, that the caller was the
// last writer. It should only be called with the lock held.
Touch() error
// Modified() checks if the most recent writer was a party other than the
// last recorded writer. It should only be called with the lock held.
Modified() (bool, error)
// TouchedSince() checks if the most recent writer modified the file (likely using Touch()) after the specified time.
TouchedSince(when time.Time) bool
// IsReadWrite() checks if the lock file is read-write
IsReadWrite() bool
// Locked() checks if lock is locked for writing by a thread in this process
Locked() bool
// Load reloads the contents of the store from disk. It should be called
// with the lock held.
Load() error
// ReloadIfChanged reloads the contents of the store from disk if it is changed.
ReloadIfChanged() error
// Save saves the contents of the store to disk. It should be called with
// the lock held, and Touch() should be called afterward before releasing the
// lock.
Save() error
// Create creates a container that has a specified ID (or generates a
// random one if an empty value is supplied) and optional names,
// based on the specified image, using the specified layer as its
// read-write layer.
// The maps in the container's options structure are recorded for the
// convenience of the caller, nothing more.
Create(id string, names []string, image, layer, metadata string, options *ContainerOptions) (*Container, error)
// updateNames modifies names associated with a container based on (op, names).
updateNames(id string, names []string, op updateNameOperation) error
// Get retrieves information about a container given an ID or name.
Get(id string) (*Container, error)
// Exists checks if there is a container with the given ID or name.
Exists(id string) bool
// Delete removes the record of the container.
Delete(id string) error
// Wipe removes records of all containers.
Wipe() error
// Lookup attempts to translate a name to an ID. Most methods do this
// implicitly.
Lookup(name string) (string, error)
// Containers returns a slice enumerating the known containers.
Containers() ([]Container, error)
}
type containerStore struct {
lockfile Locker
dir string
containers []*Container
idindex *truncindex.TruncIndex
byid map[string]*Container
bylayer map[string]*Container
byname map[string]*Container
loadMut sync.Mutex
}
func copyContainer(c *Container) *Container {
return &Container{
ID: c.ID,
Names: copyStringSlice(c.Names),
ImageID: c.ImageID,
LayerID: c.LayerID,
Metadata: c.Metadata,
BigDataNames: copyStringSlice(c.BigDataNames),
BigDataSizes: copyStringInt64Map(c.BigDataSizes),
BigDataDigests: copyStringDigestMap(c.BigDataDigests),
Created: c.Created,
UIDMap: copyIDMap(c.UIDMap),
GIDMap: copyIDMap(c.GIDMap),
Flags: copyStringInterfaceMap(c.Flags),
}
}
func (c *Container) MountLabel() string {
if label, ok := c.Flags[mountLabelFlag].(string); ok {
return label
}
return ""
}
func (c *Container) ProcessLabel() string {
if label, ok := c.Flags[processLabelFlag].(string); ok {
return label
}
return ""
}
func (c *Container) MountOpts() []string {
switch value := c.Flags[mountOptsFlag].(type) {
case []string:
return value
case []interface{}:
var mountOpts []string
for _, v := range value {
if flag, ok := v.(string); ok {
mountOpts = append(mountOpts, flag)
}
}
return mountOpts
default:
return nil
}
}
// startWriting makes sure the store is fresh, and locks it for writing.
// If this succeeds, the caller MUST call stopWriting().
func (r *containerStore) startWriting() error {
r.lockfile.Lock()
succeeded := false
defer func() {
if !succeeded {
r.lockfile.Unlock()
}
}()
if err := r.ReloadIfChanged(); err != nil {
return err
}
succeeded = true
return nil
}
// stopWriting releases locks obtained by startWriting.
func (r *containerStore) stopWriting() {
r.lockfile.Unlock()
}
// startReading makes sure the store is fresh, and locks it for reading.
// If this succeeds, the caller MUST call stopReading().
func (r *containerStore) startReading() error {
r.lockfile.RLock()
succeeded := false
defer func() {
if !succeeded {
r.lockfile.Unlock()
}
}()
if err := r.ReloadIfChanged(); err != nil {
return err
}
succeeded = true
return nil
}
// stopReading releases locks obtained by startReading.
func (r *containerStore) stopReading() {
r.lockfile.Unlock()
}
func (r *containerStore) Containers() ([]Container, error) {
containers := make([]Container, len(r.containers))
for i := range r.containers {
containers[i] = *copyContainer(r.containers[i])
}
return containers, nil
}
func (r *containerStore) containerspath() string {
return filepath.Join(r.dir, "containers.json")
}
func (r *containerStore) datadir(id string) string {
return filepath.Join(r.dir, id)
}
func (r *containerStore) datapath(id, key string) string {
return filepath.Join(r.datadir(id), makeBigDataBaseName(key))
}
func (r *containerStore) Load() error {
needSave := false
rpath := r.containerspath()
data, err := os.ReadFile(rpath)
if err != nil && !os.IsNotExist(err) {
return err
}
containers := []*Container{}
layers := make(map[string]*Container)
idlist := []string{}
ids := make(map[string]*Container)
names := make(map[string]*Container)
if err = json.Unmarshal(data, &containers); len(data) == 0 || err == nil {
idlist = make([]string, 0, len(containers))
for n, container := range containers {
idlist = append(idlist, container.ID)
ids[container.ID] = containers[n]
layers[container.LayerID] = containers[n]
for _, name := range container.Names {
if conflict, ok := names[name]; ok {
r.removeName(conflict, name)
needSave = true
}
names[name] = containers[n]
}
}
}
r.containers = containers
r.idindex = truncindex.NewTruncIndex(idlist) // Invalid values in idlist are ignored: they are not a reason to refuse processing the whole store.
r.byid = ids
r.bylayer = layers
r.byname = names
if needSave {
return r.Save()
}
return nil
}
func (r *containerStore) Save() error {
if !r.Locked() {
return errors.New("container store is not locked")
}
rpath := r.containerspath()
if err := os.MkdirAll(filepath.Dir(rpath), 0700); err != nil {
return err
}
jdata, err := json.Marshal(&r.containers)
if err != nil {
return err
}
if err := ioutils.AtomicWriteFile(rpath, jdata, 0600); err != nil {
return err
}
return r.Touch()
}
func newContainerStore(dir string) (rwContainerStore, error) {
if err := os.MkdirAll(dir, 0700); err != nil {
return nil, err
}
lockfile, err := GetLockfile(filepath.Join(dir, "containers.lock"))
if err != nil {
return nil, err
}
cstore := containerStore{
lockfile: lockfile,
dir: dir,
containers: []*Container{},
byid: make(map[string]*Container),
bylayer: make(map[string]*Container),
byname: make(map[string]*Container),
}
cstore.Lock()
defer cstore.Unlock()
if err := cstore.Load(); err != nil {
return nil, err
}
return &cstore, nil
}
func (r *containerStore) lookup(id string) (*Container, bool) {
if container, ok := r.byid[id]; ok {
return container, ok
} else if container, ok := r.byname[id]; ok {
return container, ok
} else if container, ok := r.bylayer[id]; ok {
return container, ok
} else if longid, err := r.idindex.Get(id); err == nil {
if container, ok := r.byid[longid]; ok {
return container, ok
}
}
return nil, false
}
func (r *containerStore) ClearFlag(id string, flag string) error {
container, ok := r.lookup(id)
if !ok {
return ErrContainerUnknown
}
delete(container.Flags, flag)
return r.Save()
}
func (r *containerStore) SetFlag(id string, flag string, value interface{}) error {
container, ok := r.lookup(id)
if !ok {
return ErrContainerUnknown
}
if container.Flags == nil {
container.Flags = make(map[string]interface{})
}
container.Flags[flag] = value
return r.Save()
}
func (r *containerStore) Create(id string, names []string, image, layer, metadata string, options *ContainerOptions) (container *Container, err error) {
if id == "" {
id = stringid.GenerateRandomID()
_, idInUse := r.byid[id]
for idInUse {
id = stringid.GenerateRandomID()
_, idInUse = r.byid[id]
}
}
if _, idInUse := r.byid[id]; idInUse {
return nil, ErrDuplicateID
}
if options.MountOpts != nil {
options.Flags[mountOptsFlag] = append([]string{}, options.MountOpts...)
}
if options.Volatile {
options.Flags[volatileFlag] = true
}
names = dedupeNames(names)
for _, name := range names {
if _, nameInUse := r.byname[name]; nameInUse {
return nil, fmt.Errorf("the container name %q is already in use by %s. You have to remove that container to be able to reuse that name: %w", name, r.byname[name].ID, ErrDuplicateName)
}
}
if err := hasOverlappingRanges(options.UIDMap); err != nil {
return nil, err
}
if err := hasOverlappingRanges(options.GIDMap); err != nil {
return nil, err
}
if err == nil {
container = &Container{
ID: id,
Names: names,
ImageID: image,
LayerID: layer,
Metadata: metadata,
BigDataNames: []string{},
BigDataSizes: make(map[string]int64),
BigDataDigests: make(map[string]digest.Digest),
Created: time.Now().UTC(),
Flags: copyStringInterfaceMap(options.Flags),
UIDMap: copyIDMap(options.UIDMap),
GIDMap: copyIDMap(options.GIDMap),
}
r.containers = append(r.containers, container)
r.byid[id] = container
// This can only fail on duplicate IDs, which shouldnt happen — and in that case the index is already in the desired state anyway.
// Implementing recovery from an unlikely and unimportant failure here would be too risky.
_ = r.idindex.Add(id)
r.bylayer[layer] = container
for _, name := range names {
r.byname[name] = container
}
err = r.Save()
container = copyContainer(container)
}
return container, err
}
func (r *containerStore) Metadata(id string) (string, error) {
if container, ok := r.lookup(id); ok {
return container.Metadata, nil
}
return "", ErrContainerUnknown
}
func (r *containerStore) SetMetadata(id, metadata string) error {
if container, ok := r.lookup(id); ok {
container.Metadata = metadata
return r.Save()
}
return ErrContainerUnknown
}
func (r *containerStore) removeName(container *Container, name string) {
container.Names = stringSliceWithoutValue(container.Names, name)
}
func (r *containerStore) updateNames(id string, names []string, op updateNameOperation) error {
container, ok := r.lookup(id)
if !ok {
return ErrContainerUnknown
}
oldNames := container.Names
names, err := applyNameOperation(oldNames, names, op)
if err != nil {
return err
}
for _, name := range oldNames {
delete(r.byname, name)
}
for _, name := range names {
if otherContainer, ok := r.byname[name]; ok {
r.removeName(otherContainer, name)
}
r.byname[name] = container
}
container.Names = names
return r.Save()
}
func (r *containerStore) Delete(id string) error {
container, ok := r.lookup(id)
if !ok {
return ErrContainerUnknown
}
id = container.ID
toDeleteIndex := -1
for i, candidate := range r.containers {
if candidate.ID == id {
toDeleteIndex = i
break
}
}
delete(r.byid, id)
// This can only fail if the ID is already missing, which shouldnt happen — and in that case the index is already in the desired state anyway.
// The stores Delete method is used on various paths to recover from failures, so this should be robust against partially missing data.
_ = r.idindex.Delete(id)
delete(r.bylayer, container.LayerID)
for _, name := range container.Names {
delete(r.byname, name)
}
if toDeleteIndex != -1 {
// delete the container at toDeleteIndex
if toDeleteIndex == len(r.containers)-1 {
r.containers = r.containers[:len(r.containers)-1]
} else {
r.containers = append(r.containers[:toDeleteIndex], r.containers[toDeleteIndex+1:]...)
}
}
if err := r.Save(); err != nil {
return err
}
if err := os.RemoveAll(r.datadir(id)); err != nil {
return err
}
return nil
}
func (r *containerStore) Get(id string) (*Container, error) {
if container, ok := r.lookup(id); ok {
return copyContainer(container), nil
}
return nil, ErrContainerUnknown
}
func (r *containerStore) Lookup(name string) (id string, err error) {
if container, ok := r.lookup(name); ok {
return container.ID, nil
}
return "", ErrContainerUnknown
}
func (r *containerStore) Exists(id string) bool {
_, ok := r.lookup(id)
return ok
}
func (r *containerStore) BigData(id, key string) ([]byte, error) {
if key == "" {
return nil, fmt.Errorf("can't retrieve container big data value for empty name: %w", ErrInvalidBigDataName)
}
c, ok := r.lookup(id)
if !ok {
return nil, ErrContainerUnknown
}
return os.ReadFile(r.datapath(c.ID, key))
}
func (r *containerStore) BigDataSize(id, key string) (int64, error) {
if key == "" {
return -1, fmt.Errorf("can't retrieve size of container big data with empty name: %w", ErrInvalidBigDataName)
}
c, ok := r.lookup(id)
if !ok {
return -1, ErrContainerUnknown
}
if c.BigDataSizes == nil {
c.BigDataSizes = make(map[string]int64)
}
if size, ok := c.BigDataSizes[key]; ok {
return size, nil
}
if data, err := r.BigData(id, key); err == nil && data != nil {
if err = r.SetBigData(id, key, data); err == nil {
c, ok := r.lookup(id)
if !ok {
return -1, ErrContainerUnknown
}
if size, ok := c.BigDataSizes[key]; ok {
return size, nil
}
} else {
return -1, err
}
}
return -1, ErrSizeUnknown
}
func (r *containerStore) BigDataDigest(id, key string) (digest.Digest, error) {
if key == "" {
return "", fmt.Errorf("can't retrieve digest of container big data value with empty name: %w", ErrInvalidBigDataName)
}
c, ok := r.lookup(id)
if !ok {
return "", ErrContainerUnknown
}
if c.BigDataDigests == nil {
c.BigDataDigests = make(map[string]digest.Digest)
}
if d, ok := c.BigDataDigests[key]; ok {
return d, nil
}
if data, err := r.BigData(id, key); err == nil && data != nil {
if err = r.SetBigData(id, key, data); err == nil {
c, ok := r.lookup(id)
if !ok {
return "", ErrContainerUnknown
}
if d, ok := c.BigDataDigests[key]; ok {
return d, nil
}
} else {
return "", err
}
}
return "", ErrDigestUnknown
}
func (r *containerStore) BigDataNames(id string) ([]string, error) {
c, ok := r.lookup(id)
if !ok {
return nil, ErrContainerUnknown
}
return copyStringSlice(c.BigDataNames), nil
}
func (r *containerStore) SetBigData(id, key string, data []byte) error {
if key == "" {
return fmt.Errorf("can't set empty name for container big data item: %w", ErrInvalidBigDataName)
}
c, ok := r.lookup(id)
if !ok {
return ErrContainerUnknown
}
if err := os.MkdirAll(r.datadir(c.ID), 0700); err != nil {
return err
}
err := ioutils.AtomicWriteFile(r.datapath(c.ID, key), data, 0600)
if err == nil {
save := false
if c.BigDataSizes == nil {
c.BigDataSizes = make(map[string]int64)
}
oldSize, sizeOk := c.BigDataSizes[key]
c.BigDataSizes[key] = int64(len(data))
if c.BigDataDigests == nil {
c.BigDataDigests = make(map[string]digest.Digest)
}
oldDigest, digestOk := c.BigDataDigests[key]
newDigest := digest.Canonical.FromBytes(data)
c.BigDataDigests[key] = newDigest
if !sizeOk || oldSize != c.BigDataSizes[key] || !digestOk || oldDigest != newDigest {
save = true
}
addName := true
for _, name := range c.BigDataNames {
if name == key {
addName = false
break
}
}
if addName {
c.BigDataNames = append(c.BigDataNames, key)
save = true
}
if save {
err = r.Save()
}
}
return err
}
func (r *containerStore) Wipe() error {
ids := make([]string, 0, len(r.byid))
for id := range r.byid {
ids = append(ids, id)
}
for _, id := range ids {
if err := r.Delete(id); err != nil {
return err
}
}
return nil
}
func (r *containerStore) Lock() {
r.lockfile.Lock()
}
func (r *containerStore) Unlock() {
r.lockfile.Unlock()
}
func (r *containerStore) Touch() error {
return r.lockfile.Touch()
}
func (r *containerStore) Modified() (bool, error) {
return r.lockfile.Modified()
}
func (r *containerStore) IsReadWrite() bool {
return r.lockfile.IsReadWrite()
}
func (r *containerStore) TouchedSince(when time.Time) bool {
return r.lockfile.TouchedSince(when)
}
func (r *containerStore) Locked() bool {
return r.lockfile.Locked()
}
func (r *containerStore) ReloadIfChanged() error {
r.loadMut.Lock()
defer r.loadMut.Unlock()
modified, err := r.Modified()
if err == nil && modified {
return r.Load()
}
return err
}