github.com/rawahars/moby@v24.0.4+incompatible/volume/mounts/mounts.go (about) 1 package mounts // import "github.com/docker/docker/volume/mounts" 2 3 import ( 4 "context" 5 "fmt" 6 "os" 7 "path/filepath" 8 "syscall" 9 10 "github.com/containerd/containerd/log" 11 mounttypes "github.com/docker/docker/api/types/mount" 12 "github.com/docker/docker/pkg/idtools" 13 "github.com/docker/docker/pkg/stringid" 14 "github.com/docker/docker/volume" 15 "github.com/opencontainers/selinux/go-selinux/label" 16 "github.com/pkg/errors" 17 "github.com/sirupsen/logrus" 18 ) 19 20 // MountPoint is the intersection point between a volume and a container. It 21 // specifies which volume is to be used and where inside a container it should 22 // be mounted. 23 // 24 // Note that this type is embedded in `container.Container` object and persisted to disk. 25 // Changes to this struct need to by synced with on disk state. 26 type MountPoint struct { 27 // Source is the source path of the mount. 28 // E.g. `mount --bind /foo /bar`, `/foo` is the `Source`. 29 Source string 30 // Destination is the path relative to the container root (`/`) to the mount point 31 // It is where the `Source` is mounted to 32 Destination string 33 // RW is set to true when the mountpoint should be mounted as read-write 34 RW bool 35 // Name is the name reference to the underlying data defined by `Source` 36 // e.g., the volume name 37 Name string 38 // Driver is the volume driver used to create the volume (if it is a volume) 39 Driver string 40 // Type of mount to use, see `Type<foo>` definitions in github.com/docker/docker/api/types/mount 41 Type mounttypes.Type `json:",omitempty"` 42 // Volume is the volume providing data to this mountpoint. 43 // This is nil unless `Type` is set to `TypeVolume` 44 Volume volume.Volume `json:"-"` 45 46 // Mode is the comma separated list of options supplied by the user when creating 47 // the bind/volume mount. 48 // Note Mode is not used on Windows 49 Mode string `json:"Relabel,omitempty"` // Originally field was `Relabel`" 50 51 // Propagation describes how the mounts are propagated from the host into the 52 // mount point, and vice-versa. 53 // See https://www.kernel.org/doc/Documentation/filesystems/sharedsubtree.txt 54 // Note Propagation is not used on Windows 55 Propagation mounttypes.Propagation `json:",omitempty"` // Mount propagation string 56 57 // Specifies if data should be copied from the container before the first mount 58 // Use a pointer here so we can tell if the user set this value explicitly 59 // This allows us to error out when the user explicitly enabled copy but we can't copy due to the volume being populated 60 CopyData bool `json:"-"` 61 // ID is the opaque ID used to pass to the volume driver. 62 // This should be set by calls to `Mount` and unset by calls to `Unmount` 63 ID string `json:",omitempty"` 64 65 // Sepc is a copy of the API request that created this mount. 66 Spec mounttypes.Mount 67 68 // Some bind mounts should not be automatically created. 69 // (Some are auto-created for backwards-compatibility) 70 // This is checked on the API but setting this here prevents race conditions. 71 // where a bind dir existed during validation was removed before reaching the setup code. 72 SkipMountpointCreation bool 73 74 // Track usage of this mountpoint 75 // Specifically needed for containers which are running and calls to `docker cp` 76 // because both these actions require mounting the volumes. 77 active int 78 } 79 80 // Cleanup frees resources used by the mountpoint 81 func (m *MountPoint) Cleanup() error { 82 if m.Volume == nil || m.ID == "" { 83 return nil 84 } 85 86 if err := m.Volume.Unmount(m.ID); err != nil { 87 return errors.Wrapf(err, "error unmounting volume %s", m.Volume.Name()) 88 } 89 90 m.active-- 91 if m.active == 0 { 92 m.ID = "" 93 } 94 return nil 95 } 96 97 // Setup sets up a mount point by either mounting the volume if it is 98 // configured, or creating the source directory if supplied. 99 // The, optional, checkFun parameter allows doing additional checking 100 // before creating the source directory on the host. 101 func (m *MountPoint) Setup(mountLabel string, rootIDs idtools.Identity, checkFun func(m *MountPoint) error) (path string, err error) { 102 if m.SkipMountpointCreation { 103 return m.Source, nil 104 } 105 106 defer func() { 107 if err != nil || !label.RelabelNeeded(m.Mode) { 108 return 109 } 110 111 var sourcePath string 112 sourcePath, err = filepath.EvalSymlinks(m.Source) 113 if err != nil { 114 path = "" 115 err = errors.Wrapf(err, "error evaluating symlinks from mount source %q", m.Source) 116 return 117 } 118 err = label.Relabel(sourcePath, mountLabel, label.IsShared(m.Mode)) 119 if errors.Is(err, syscall.ENOTSUP) { 120 err = nil 121 } 122 if err != nil { 123 path = "" 124 err = errors.Wrapf(err, "error setting label on mount source '%s'", sourcePath) 125 } 126 }() 127 128 if m.Volume != nil { 129 id := m.ID 130 if id == "" { 131 id = stringid.GenerateRandomID() 132 } 133 path, err := m.Volume.Mount(id) 134 if err != nil { 135 return "", errors.Wrapf(err, "error while mounting volume '%s'", m.Source) 136 } 137 138 m.ID = id 139 m.active++ 140 return path, nil 141 } 142 143 if len(m.Source) == 0 { 144 return "", fmt.Errorf("Unable to setup mount point, neither source nor volume defined") 145 } 146 147 if m.Type == mounttypes.TypeBind { 148 // Before creating the source directory on the host, invoke checkFun if it's not nil. One of 149 // the use case is to forbid creating the daemon socket as a directory if the daemon is in 150 // the process of shutting down. 151 if checkFun != nil { 152 if err := checkFun(m); err != nil { 153 return "", err 154 } 155 } 156 157 // idtools.MkdirAllNewAs() produces an error if m.Source exists and is a file (not a directory) 158 // also, makes sure that if the directory is created, the correct remapped rootUID/rootGID will own it 159 if err := idtools.MkdirAllAndChownNew(m.Source, 0755, rootIDs); err != nil { 160 if perr, ok := err.(*os.PathError); ok { 161 if perr.Err != syscall.ENOTDIR { 162 return "", errors.Wrapf(err, "error while creating mount source path '%s'", m.Source) 163 } 164 } 165 } 166 } 167 return m.Source, nil 168 } 169 170 func (m *MountPoint) LiveRestore(ctx context.Context) error { 171 if m.Volume == nil { 172 logrus.Debug("No volume to restore") 173 return nil 174 } 175 176 lrv, ok := m.Volume.(volume.LiveRestorer) 177 if !ok { 178 log.G(ctx).WithField("volume", m.Volume.Name()).Debugf("Volume does not support live restore: %T", m.Volume) 179 return nil 180 } 181 182 id := m.ID 183 if id == "" { 184 id = stringid.GenerateRandomID() 185 } 186 187 if err := lrv.LiveRestoreVolume(ctx, id); err != nil { 188 return errors.Wrapf(err, "error while restoring volume '%s'", m.Source) 189 } 190 191 m.ID = id 192 m.active++ 193 return nil 194 } 195 196 // Path returns the path of a volume in a mount point. 197 func (m *MountPoint) Path() string { 198 if m.Volume != nil { 199 return m.Volume.Path() 200 } 201 return m.Source 202 } 203 204 func errInvalidMode(mode string) error { 205 return errors.Errorf("invalid mode: %v", mode) 206 } 207 208 func errInvalidSpec(spec string) error { 209 return errors.Errorf("invalid volume specification: '%s'", spec) 210 }