#!/bin/bash
# attachiscsi.sh - Attach iSCSI devices attached to the instance to the operating system
#
# Author: Steven B. Nelson, Sr. Solutions Architect
#       Oracle Bare Metal Cloud Services
#
# 12 March 2017
# Copyright Oracle, Inc.  All rights reserved.
# Make FIFO pipes for the two loops below
mkfifo discpipe
mkfifo sesspipe

# Find all the iSCSI Block Storage volumes attached to the instance but
# not configured for use on the instance.  Basically, get a list of the
# volumes that the instance can see, the loop through the ones it has,
# and add volumes not already configured on the instance.
#
# First get the list of volumes visible (attached) to the instance
iscsiadm -m discovery -t st -p 169.254.0.2:3260 | grep -v uefi | awk '{print $2}' > discpipe &

# Loop through the list (via the named FIFO pipe below)
while read target
do
    # Get the list of the currently attached Block Storage volumes
    iscsiadm -m session -P 0 | grep -v uefi | awk '{print $4}' > sesspipe &

    # Set a flag, and loop through the sessions (attached, but not configured)
    # and see if the volumes match.  If so, skip to the next until we get
    # through the list.  Session list is via the pipe.
    found="false"
    while read session
    do
        if [ ${target} = ${session} ]
        then
            found="true"
            break
        fi
    done < sesspipe

    # If the volume is not found, configure it.  Get the resulting device file.
    if [ ${found} = "false" ]
    then
        iscsiadm -m node -o new -T ${target} -p 169.254.0.2:3260
        iscsiadm -m node -o update -T ${target} -n node.startup -v automatic
        iscsiadm -m node -T ${target} -p 169.254.0.2:3260 -l
        sleep 5
    fi
done < discpipe

# Remove the FIFOs
find . -maxdepth 1 -type p -exec rm {} \;