CSI-BlockDevices

CSI-BlockDevices is an implementation of a CSI plugin for locally attached block devices. Block devices can be exposed to the plugin by symlinking them into a directory, by default /dev/disk/csi-blockdevices. See sample commands for details

It is structured such that it can be compiled into a standalone golang binary that can be executed to meet the requirements of a CSI plugin. Furthermore, the core block and mount logic is separated into a block go package that can be imported for use by other programs.

Installation

You'll need a working Go installation. From there, download and installation is as simple as:

go get github.com/codedellemc/csi-blockdevices

This will download the source to $GOPATH/src/github.com/codedellemc/csi-blockdevices, and will build install the binary csi-blockdevices to $GOPATH/bin/csi-blockdevices.

Note that this plugin only works on Linux OS.

Starting the plugin

In order to execute the binary, you must set the env var CSI_ENDPOINT. CSI is intended to only run over UNIX domain sockets, so a simple way to set this endpoint to a .sock file in the same directory as the project is

export CSI_ENDPOINT=unix://$(go list -f '{{.Dir}}' github.com/codedellemc/csi-blockdevices)/csi.sock

With that in place, you can start the plugin (assuming that $GOPATH/bin is in your $PATH):

$ ./csi-blockdevices
INFO[0000] .Serve                                        name=csi-blockdevices

Use ctrl-C to exit.

You can enable debug logging (all logging goes to stdout) by setting the X_CSI_BD_DEBUG env var. It doesn't matter what value you set it to, just that it is set. For example:

$ X_CSI_BD_DEBUG= ./csi-blockdevices
INFO[0000] .Serve                                        name=csi-blockdevices
DEBU[0000] Added Controller Service
DEBU[0000] Added Node Service
^CINFO[0002] Shutting down server

For reference, the available env vars are:

name	purpose	default
CSI_ENDPOINT	Set path to UNIX domain socket file	n/a
X_CSI_BD_DEBUG	enable debug logging to stdout	n/a
X_CSI_BD_NODEONLY	Only run the Node Service (no Controller service)	n/a
X_CSI_BD_CONTROLLERONLY	Only run the Controller Service (no Node service)	n/a
X_CSI_BD_DEVDIR	Directory to search for available block devices	/dev/disk/csi-blockdevices

Note that the Identity service is required to always be running, and that the default behavior is to also run both the Controller and the Node service

Using the plugin

All communication with the plugin is done via gRPC. The easiest way to interact with a CSI plugin via CLI is to use the csc tool found in GoCSI.

You can install this tool with:

go get github.com/codedellemc/gocsi
go install github.com/codedellemc/gocsi/csc

With $GOPATH/bin in your $PATH, you can issue commands using the csc command. You will want to use a separate shell from where you are running the csi-blockdevices binary, and as such you will once again need to do:

export CSI_ENDPOINT=unix://$(go list -f '{{.Dir}}' github.com/codedellemc/csi-blockdevices)/csi.sock

Here are some sample commands:

$ csc gets
0.0.0
$ csc getp
csi-blockdevices	0.1.0
$ mkdir /dev/disk/csi-blockdevices
$ cd /dev/disk/csi-blockdevices
$ dd if=/dev/zero of=test.img bs=1024 count=102400 #makes 100MiB disk image
$ losetup /dev/loop0 test.img #attaches disk image to /dev/loop0
$ ln -s /dev/loop0 # creates symlink named loop0 -> /dev/loop0
$ csc ls
name=loop0
$ mkdir /mnt/test
$ mkdir /mnt/test2
$ csc mnt -mode 1 -t xfs -targetPath /mnt/test id=loop0
$ cat /proc/mounts | grep loop
/dev/loop0 /dev/disk/csi-blockdevices/.mounts/loop0 xfs rw,seclabel,relatime,attr2,inode64,noquota 0 0
/dev/loop0 /mnt/test xfs rw,seclabel,relatime,attr2,inode64,noquota 0 0
$ csc mnt -mode 1 -t xfs -targetPath /mnt/test2 id=loop0
$ cat /proc/mounts | grep loop
/dev/loop0 /dev/disk/csi-blockdevices/.mounts/loop0 xfs rw,seclabel,relatime,attr2,inode64,noquota 0 0
/dev/loop0 /mnt/test xfs rw,seclabel,relatime,attr2,inode64,noquota 0 0
/dev/loop0 /mnt/test2 xfs rw,seclabel,relatime,attr2,inode64,noquota 0 0
$ csc umount -targetPath /mnt/test id=loop0
$ cat /proc/mounts | grep loop
/dev/loop0 /dev/disk/csi-blockdevices/.mounts/loop0 xfs rw,seclabel,relatime,attr2,inode64,noquota 0 0
/dev/loop0 /mnt/test2 xfs rw,seclabel,relatime,attr2,inode64,noquota 0 0
$ csc umount -targetPath /mnt/test2 id=loop0
$ cat /proc/mounts | grep loop
$