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.\" ========================================================================
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.IX Title "nbdkit-cdi-plugin 1"
.TH nbdkit-cdi-plugin 1 2024-01-17 nbdkit-1.36.3 NBDKIT
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH NAME
nbdkit\-cdi\-plugin \- export a layer from a container image
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& nbdkit cdi [name=]NAME[:TAG|@DIGEST] [layer=N]
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
\&\f(CW\*(C`nbdkit\-cdi\-plugin\*(C'\fR (Containerized Data Importer plugin) is a plugin
for \fBnbdkit\fR\|(1) which downloads a container image using
\&\fBpodman\-pull\fR\|(1) and makes a single layer available over NBD.  The
plugin is essentially a convenient wrapper around \fBpodman\fR\|(1) and
\&\fBjq\fR\|(1) and requires both tools to be installed.
.SH EXAMPLES
.IX Header "EXAMPLES"
Given a Containerized Data Importer (CDI) registry image containing a
VM disk, you can export the whole layer using:
.PP
.Vb 1
\& $ nbdkit cdi quay.io/kubevirt/fedora\-cloud\-container\-disk\-demo
.Ve
.PP
The layer exported over NBD is a tar file:
.PP
.Vb 2
\& $ nbdcopy nbd://localhost \- | file \-
\& \-: POSIX tar archive
.Ve
.PP
To export only the VM disk image in this layer, combine this plugin
with \fBnbdkit\-tar\-filter\fR\|(1).  In the example below the file exposed
inside the tar archive is a qcow2 image so you can turn it into a raw
NBD export of the virtual machine using \fBnbdkit\-qcow2dec\-filter\fR\|(1):
.PP
.Vb 8
\& ┌──────────────────────────────────────────┐
\& │ fedora\-cloud\-container\-disk\-demo layer=0 │
\& │ (uncompressed tar file)                  │
\& │ ┌──────────────────────────────────────┐ │
\& │ │ ./disk/downloaded                    │ │
\& │ │ (qcow2 image)                        │ │
\& │ └──────────────────────────────────────┘ │
\& └──────────────────────────────────────────┘
\&
\& $ nbdkit cdi \e
\&         \-\-filter=qcow2dec \e
\&         \-\-filter=tar tar\-entry=./disk/downloaded \e
\&         quay.io/kubevirt/fedora\-cloud\-container\-disk\-demo \e
\&         \-\-run \*(Aqnbdinfo "$uri"\*(Aq
\& export="":
\&     export\-size: 4294967296 (4G)
\&     content: DOS/MBR boot sector
\& [...]
.Ve
.SH PARAMETERS
.IX Header "PARAMETERS"
.IP [\fBname=\fR]NAME[:TAG|@DIGEST] 4
.IX Item "[name=]NAME[:TAG|@DIGEST]"
The name or URI of the container image.  This is passed to
\&\fBpodman\-pull\fR\|(1).
.Sp
\&\f(CW\*(C`name=\*(C'\fR is a magic config key and may be omitted in most cases.
See "Magic parameters" in \fBnbdkit\fR\|(1).
.IP \fBlayer=\fRN 4
.IX Item "layer=N"
Export the N'th layer (instead of layer 0).
.SH "ENVIRONMENT VARIABLES"
.IX Header "ENVIRONMENT VARIABLES"
.ie n .IP """TMPDIR""" 4
.el .IP \f(CWTMPDIR\fR 4
.IX Item "TMPDIR"
A temporary copy of the layer is created in \f(CW\*(C`TMPDIR\*(C'\fR.  If this
environment variable is not set then \fI/var/tmp\fR is used instead.
.SH FILES
.IX Header "FILES"
.ie n .IP \fR\fI$plugindir\fR\fI/nbdkit\-cdi\-plugin.so\fR 4
.el .IP \fR\f(CI$plugindir\fR\fI/nbdkit\-cdi\-plugin.so\fR 4
.IX Item "$plugindir/nbdkit-cdi-plugin.so"
The plugin.
.Sp
Use \f(CW\*(C`nbdkit \-\-dump\-config\*(C'\fR to find the location of \f(CW$plugindir\fR.
.SH VERSION
.IX Header "VERSION"
\&\f(CW\*(C`nbdkit\-cdi\-plugin\*(C'\fR first appeared in nbdkit 1.22.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBnbdkit\fR\|(1),
\&\fBnbdkit\-plugin\fR\|(3),
\&\fBnbdkit\-qcow2dec\-filter\fR\|(1),
\&\fBnbdkit\-tar\-filter\fR\|(1),
\&\fBpodman\fR\|(1),
\&\fBpodman\-pull\fR\|(1),
\&\fBjq\fR\|(1),
https://github.com/kubevirt/containerized\-data\-importer/blob/master/doc/image\-from\-registry.md.
.SH AUTHORS
.IX Header "AUTHORS"
Richard W.M. Jones
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright Red Hat
.SH LICENSE
.IX Header "LICENSE"
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
.IP \(bu 4
Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
.IP \(bu 4
Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
.IP \(bu 4
Neither the name of Red Hat nor the names of its contributors may be
used to endorse or promote products derived from this software without
specific prior written permission.
.PP
THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.