Merge pull request rexray#1133 from codenrhoden/docs/csi-nfs

Use CentOS as base for csi-nfs docker plugin

.docker/plugins/csi-nfs/.Dockerfile

@@ -1,14 +1,12 @@
-FROM alpine:3.6
+FROM centos:7.4.1708
 
-RUN apk update
-RUN apk add xfsprogs e2fsprogs ca-certificates nfs-utils
+RUN yum install -y nfs-utils && yum clean all && rm -rf /var/cache/yum
 
-RUN mkdir -p /lib64 && ln -s /lib/libc.musl-x86_64.so.1 /lib64/ld-linux-x86-64.so.2
 RUN mkdir -p /etc/rexray /run/docker/plugins /var/lib/rexray/volumes
 ADD rexray /usr/bin/rexray
 ADD rexray.yml /etc/rexray/rexray.yml
 
-ADD rexray.sh /rexray.sh
+ADD .rexray.sh /rexray.sh
 RUN chmod +x /rexray.sh
 
 CMD [ "rexray", "start", "--nopid" ]

.docker/plugins/csi-nfs/.rexray.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+# shellcheck shell=dash
+set -e
+
+# first arg is `--some-option`
+if [ "$(echo "$1" | \
+	awk  '{ string=substr($0, 1, 1); print string; }' )" = '-' ]; then
+	set -- rexray start --nopid "$@"
+fi
+
+#set default rexray options
+REXRAY_FSTYPE="${REXRAY_FSTYPE:-ext4}"
+REXRAY_LOGLEVEL="${REXRAY_LOGLEVEL:-warn}"
+REXRAY_PREEMPT="${REXRAY_PREEMPT:-false}"
+
+if [ "$1" = 'rexray' ]; then
+
+	for rexray_option in \
+		fsType \
+		loglevel \
+		preempt \
+	; do
+		val=$(eval echo "\$REXRAY_$(echo $rexray_option | \
+			awk '{print toupper($0)}')")
+		if [ "$val" ]; then
+			sed -ri 's/^([\ ]*'"$rexray_option"':).*/\1 '"$val"'/' \
+				/etc/rexray/rexray.yml
+		fi
+	done
+
+fi
+
+exec "$@"

.docs/user-guide/schedulers/docker/plug-ins/csi-nfs.md

@@ -27,3 +27,54 @@ The following environment variables can be used to configure the plug-in:
 | Environment Variable | Description | Default | Required |
 |---------------------|-------------|---------|---------|
 | `X_CSI_NFS_VOLUMES` | A list of NFS volume mappings | | |
+
+## Examples
+
+To use the `csi-nfs` plug-in, you must first create a volume using the
+`docker volume create` command (unless predefined using `X_CSI_NFS_VOLUMES`, see
+`Limitations` below), specifying both the NFS server host and the
+exported path:
+
+```sh
+$ docker volume create -d rexray/csi-nfs -o host=192.168.75.2 -o export=/data test
+$ docker volume ls
+DRIVER                           VOLUME NAME
+rexray/csi-nfs                   test
+```
+
+With the volume created, you can then use it in your containers:
+
+```sh
+$ docker run -it -v test:/mnt alpine sh
+/ # mount | grep nfs
+192.168.75.2:/data on /mnt type nfs4 (rw,relatime,vers=4.1,rsize=65536,wsize=65536,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=10.0.2.15,local_lock=none,addr=192.168.75.2)
+```
+
+### Limitations
+
+`csi-nfs` is an early proof of concept to demonstrate a Docker managed plug-in functioning with [CSI](https://github.com/container-storage-interface/spec). It is
+not intended to replace Docker's
+[native NFS](https://docs.docker.com/engine/reference/commandline/volume_create/#driver-specific-options)
+functionality.
+
+Currently, the plug-in only supports NFSv4, and does not allow for custom options
+to be passed through to the mount command. In other words, the NFS mount command
+will always be of the form `mount -t nfs {server}:{export} {mountpath}`.
+
+When doing a `docker volume create` command, the `csi-nfs` plug-in merely creates
+a reference to an existing NFS volume with the details you have provided. This
+reference is only persisted across the lifetime of the plug-in, which means if the
+plug-in is removed and recreated, or upgraded, the volumes previously seen in
+`docker volume ls` will disappear. To circumvent this behavior, you can seed the
+plug-in with the NFS volume definitions using the `X_CSI_NFS_VOLUMES` env var.
+For example:
+
+```sh
+$ docker plugin set rexray/csi-nfs X_CSI_NFS_VOLUMES="vol1=192.168.75.2:/nfsshare vol2=192.168.75.2:/share2"
+```
+
+The env var can be set during plug-in installation, or the plug-in can be disabled,
+the var set, and then enabled. However, currently only the env var or the persisted
+volumes from `docker volume create` can be used, which means if
+`docker volume create` is used to define an NFS volume, a later setting of
+`X_CSI_NFS_VOLUMES` will be ignored.