интерфейс D-Bus для systemd-importd (The D-Bus interface of systemd-importd)
Имя (Name)
org.freedesktop.import1 - The D-Bus interface of systemd-importd
Вступление (Introduction)
systemd-importd.service(8) is a system service which may be used
to import, export and download additional system images. These
images can be used by tools such as systemd-nspawn(1) to run
local containers. The service is used as the backend for
machinectl pull-raw, machinectl pull-tar and related commands.
This page describes the D-Bus interface.
Note that systemd-importd.service(8) is mostly a small companion
service for systemd-machined.service(8). Many operations to
manipulate local container and VM images are hence available via
the systemd-machined D-Bus API, c.f.
org.freedesktop.machine1(5).
Объект менеджера (The manager object)
The service exposes the following interfaces on the Manager
object on the bus:
node /org/freedesktop/import1 {
interface org.freedesktop.import1.Manager {
methods:
ImportTar(in h fd,
in s local_name,
in b force,
in b read_only,
out u transfer_id,
out o transfer_path);
ImportRaw(in h fd,
in s local_name,
in b force,
in b read_only,
out u transfer_id,
out o transfer_path);
ImportFileSystem(in h fd,
in s local_name,
in b force,
in b read_only,
out u transfer_id,
out o transfer_path);
ExportTar(in s local_name,
in h fd,
in s format,
out u transfer_id,
out o transfer_path);
ExportRaw(in s local_name,
in h fd,
in s format,
out u transfer_id,
out o transfer_path);
PullTar(in s url,
in s local_name,
in s verify_mode,
in b force,
out u transfer_id,
out o transfer_path);
PullRaw(in s url,
in s local_name,
in s verify_mode,
in b force,
out u transfer_id,
out o transfer_path);
ListTransfers(out a(usssdo) transfers);
CancelTransfer(in u transfer_id);
signals:
TransferNew(u transfer_id,
o transfer_path);
TransferRemoved(u transfer_id,
o transfer_path,
s result);
};
interface org.freedesktop.DBus.Peer { ... };
interface org.freedesktop.DBus.Introspectable { ... };
interface org.freedesktop.DBus.Properties { ... };
};
Methods
ImportTar() and ImportRaw() import a system image and place it
into /var/lib/machines/. The first argument should be a file
descriptor (opened for reading) referring to the tar or raw file
to import. It should reference a file on disk, a pipe or a
socket. When ImportTar() is used the file descriptor should refer
to a tar file, optionally compressed with gzip(1), bzip2(1), or
xz(1). systemd-importd will detect the used compression scheme
(if any) automatically. When ImportRaw() is used the file
descriptor should refer to a raw or qcow2 disk image containing
an MBR or GPT disk label, also optionally compressed with gzip,
bzip2 or xz. In either case, if the file is specified as a file
descriptor on disk, progress information is generated for the
import operation (as in that case we know the total size on
disk). If a socket or pipe is specified, progress information is
not available. The file descriptor argument is followed by a
local name for the image. This should be a name suitable as a
hostname and will be used to name the imported image below
/var/lib/machines/. A tar import is placed as a directory tree or
a btrfs(8) subvolume below /var/lib/machines/ under the specified
name with no suffix appended. A raw import is placed as a file in
/var/lib/machines/ with the .raw suffix appended. If the force
argument is true, any pre-existing image with the same name is
removed before starting the operation. Otherwise, the operation
fails if an image with the same name already exists. Finally, the
read_only argument controls whether to create a writable or
read-only image. Both methods return immediately after starting
the import, with the import transfer ongoing. They return a pair
of transfer identifier and object path, which may be used to
retrieve progress information about the transfer or to cancel it.
The transfer identifier is a simple numeric identifier, the
object path references an org.freedesktop.import1.Transfer
object, see below. Listen for a TransferRemoved signal for the
transfer ID in order to detect when a transfer is complete. The
returned transfer object is useful to determine the current
progress or log output of the ongoing import operation.
ExportTar() and ExportRaw() implement the reverse operation, and
may be used to export a system image in order to place it in a
tar or raw image. They take the machine name to export as their
first parameter, followed by a file descriptor (opened for
writing) where the tar or raw file will be written. It may either
reference a file on disk or a pipe/socket. The third argument
specifies in which compression format to write the image. It
takes one of "uncompressed", "xz", "bzip2" or "gzip", depending
on which compression scheme is required. The image written to the
specified file descriptor will be a tar file in case of
ExportTar() or a raw disk image in case of ExportRaw(). Note that
currently raw disk images may not be exported as tar files, and
vice versa. This restriction might be lifted eventually. The
method returns a transfer identifier and object path for
cancelling or tracking the export operation, similar to
ImportTar() or ImportRaw() as described above.
PullTar() and PullRaw() may be used to download, verify and
import a system image from a URL. They take an URL argument which
should point to a tar or raw file on the "http://" or "https://"
protocols, possibly compressed with xz, bzip2 or gzip. The second
argument is a local name for the image. It should be suitable as
a hostname, similar to the matching argument of the ImportTar()
and ImportRaw() methods above. The third argument indicates the
verification mode for the image. It may be one of "no",
"checksum", "signature". "no" turns off any kind of verification
of the image; "checksum" looks for a SHA256SUM file next to the
downloaded image and verifies any SHA256 hash value in that file
against the image; "signature" does the same but also tries to
authenticate the SHA256SUM file via gpg(8) first. The last
argument indicates whether to replace a possibly pre-existing
image with the same local name (if "true"), or whether to fail
(if "false"). Like the import and export calls above, these calls
return a pair of transfer identifier and object path for the
ongoing download.
ListTransfers() returns a list of ongoing import, export or
download operations as created with the six calls described
above. It returns an array of structures which consist of the
numeric transfer identifier, a string indicating the operation
(one of "import-tar", "import-raw", "export-tar", "export-raw",
"pull-tar" or "pull-raw"), a string describing the remote file
(in case of download operations this is the source URL, in case
of import/export operations this is a short string describing the
file descriptor passed in), a string with the local machine image
name, a progress value between 0.0 (for 0%) and 1.0 (for 100%),
as well as the transfer object path.
CancelTransfer() may be used to cancel an ongoing import, export
or download operation. Simply specify the transfer identifier to
cancel the ongoing operation.
Signals
The TransferNew signal is generated each time a new transfer is
started with the import, export or download calls described
above. It carries the transfer ID and object path that have just
been created.
The TransferRemoved signal is sent each time a transfer finishes,
is canceled or fails. It also carries the transfer ID and object
path, followed by a string indicating the result of the
operation, which is one of "done" (on success), "canceled" or
"failed".
THE TRANSFER OBJECT
node /org/freedesktop/import1/transfer/_1 {
interface org.freedesktop.import1.Transfer {
methods:
Cancel();
signals:
LogMessage(u priority,
s line);
properties:
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly u Id = ...;
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly s Local = '...';
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly s Remote = '...';
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly s Type = '...';
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly s Verify = '...';
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
readonly d Progress = ...;
};
interface org.freedesktop.DBus.Peer { ... };
interface org.freedesktop.DBus.Introspectable { ... };
interface org.freedesktop.DBus.Properties { ... };
};
Methods
The Cancel() method may be used to cancel the transfer. It takes
no parameters. This method is pretty much equivalent to the
CancelTransfer() method on the Manager interface (see above), but
is exposed on the Transfer object itself instead of taking a
transfer ID.
Properties
The Id property exposes the numeric transfer ID of the transfer
object.
The Local, Remote and Type properties expose the local container
name of this transfer, the remote source (in case of download:
the URL, in case of import/export: a string describing the file
descriptor passed in), and the type of operation (see the
Manager's ListTransfer() method above for an explanation of the
possible values).
The Verify property exposes the selected verification setting and
is only defined for download operations (see above).
The Progress property exposes the current progress of the
transfer as a value between 0.0 and 1.0. To show a progress bar
on screen we recommend to query this value in regular intervals,
for example every 500 ms or so.
Примеры (Examples)
Example 1. Introspect org.freedesktop.import1.Manager on the bus
$ gdbus introspect --system \
--dest org.freedesktop.import1 \
--object-path /org/freedesktop/import1
Example 2. Introspect org.freedesktop.import1.Transfer on the bus
$ gdbus introspect --system \
--dest org.freedesktop.import1 \
--object-path /org/freedesktop/import1/transfer/_1
Версии (Versions)
These D-Bus interfaces follow the usual interface versioning
guidelines
Примечание (Note)
1. the usual interface versioning guidelines
http://0pointer.de/blog/projects/versioning-dbus.html
