#! /bin/bash

## Run this script on a fresh new compute node, which should have established ssh connection to the frontend (or internet, but this is optional)

## 1
### nfs_node.txt
### Configuring compute nodes (NFS clients)
### reference: https://www.itzgeek.com/how-tos/linux/centos-how-tos/how-to-setup-nfs-server-on-centos-7-rhel-7-fedora-22.html
#### default values. dont change ###
HOSTNAME=$(cat /etc/sysconfig/network | grep HOSTNAME | awk -F "=" '{print $2}')
hostnamectl set-hostname $HOSTNAME
#### default values. dont change ###


## 5. Doing NFS configuration in current node
# Check NFS Share
# Before mounting the NFS share, check the NFS shares available on the NFS server by running the following command on the NFS client.

showmount -e 192.168.1.10

# Mount the shared directory in the NFS clients (the share directory in the frontend is supposed to be /export/share
mkdir /share
mount 192.168.1.10:/export/share /share

#Verify the mounted share on the NFS client using mount command.

mount | grep nfs

#Also, you can use the df -hT command to check the mounted NFS share.

df -hT

#Create a file on the mounted directory to verify the read and write access on NFS share.

touch /share/test_$HOSTNAME

#If the above command returns no error, you have working NFS setup

# To mount the shares automatically on every reboot, you would need to modify /etc/fstab file of your NFS client.

cp /etc/fstab /etc/fstab.orig
echo '192.168.1.10:/export/share /share nfs   nosuid,rw,sync,hard,intr  0  0' >> /etc/fstab

### replace /etc/hosts file by that shared in /share/cluster/hosts, then add to hosts the identify of current node
mv /etc/hosts /etc/hosts.orig
ln -s /share/cluster/hosts /etc/

ipaddlastnumber=$(cat /etc/sysconfig/network | grep HOSTNAME | awk -F "=" '{print $2}' | awk -F "-" '{print $3}')
echo 192.168.1.$ipaddlastnumber $HOSTNAME.local $HOSTNAME c$ipaddlastnumber >> /share/cluster/hosts
cat /share/cluster/hosts | uniq > temp
mv temp /share/cluster/hosts


# do auto exec network service restart in current noe
# see https://linuxconfig.org/how-to-automatically-execute-shell-script-at-startup-boot-on-systemd-linux for How to automatically execute shell script at startup boot on systemd Linux

# execute as su

## create /etc/systemd/system/network-service-restart.sh
echo '#!/bin/bash' > /usr/local/bin/network-service-restart.sh
echo 'service NetworkManager restart'  >> /usr/local/bin/network-service-restart.sh
echo 'service network restart'  >> /usr/local/bin/network-service-restart.sh
chmod 744 /usr/local/bin/network-service-restart.sh


## create /etc/systemd/system/service-network-restart.service
cat << EOF > /etc/systemd/system/service-network-restart.service
[Unit]
After=mysql.service

[Service]
ExecStart=/usr/local/bin/network-service-restart.sh

[Install]
WantedBy=default.target
EOF

# Next, install systemd service unit and enable it so it will be executed at the boot time:
chmod 664 /etc/systemd/system/service-network-restart.service
systemctl daemon-reload
systemctl enable service-network-restart.service

#edit /etc/resolv.conf, so that it reads 'search local \ nameserver 192.168.1.10'. This line could be overwritten when setting the eth0 using NetworkManager.
#### end of customize /etc/ssh in a fresh node


# If you wish to test your script before you reboot, run:
systemctl start service-network-restart.service
service network restart

### customize the root for the present node
mkdir -p /state/partition1
chmod -R 755 /state/partition1

if [[ -e $HOME/.ssh/id_rsa.pub ]]; then echo "pub rsa exists. Will not create any."; else yes '' | ssh-keygen -t rsa; fi


### if the nfs mount has been successful at this stage, the node should be able to see the shared directory /share/apps/local/bin/
sh /share/apps/local/bin/gen_bashrc.txt
source ~/.bashrc


## Check if the frontend is ssh-reachable
checkping=$(ping -q -c1 -W 1 192.168.1.10 | awk 'NR==4 {print $4}')
if [ $checkping -eq 0 ]
then
	echo The frontend is not responding to ping after 1 second. ssh to frontend is not yet established. 
fi

if [ $checkping -eq 1 ]
then
	echo $i is responding to ping within 1 second
	echo 'To establish passwordless ssh into frontend from current node'
	ssh-copy-id -i $HOME/.ssh/id_rsa.pub $USER@192.168.1.10
fi

# need sshpass #
yum install -y epel-release
yum install -y sshpass

#### customize /etc/ssh in a fresh node, so that ssh can work seamlessly
# edit /etc/ssh/ssh_config, so that it reads 'GSSAPIAuthentication no'
# edit /etc/ssh/sshd_config, so that it reads 'GSSAPIAuthentication no \ UseDNS no'

##### modify /etc/ssh/sshd_config
cp /etc/ssh/sshd_config /etc/ssh/sshd_config.orig
sed -i 's/GSSAPIAuthentication yes/GSSAPIAuthentication no/g' /etc/ssh/sshd_config

cp /etc/ssh/ssh_config /etc/ssh/ssh_config.orig
sed -i 's/GSSAPIAuthentication yes/GSSAPIAuthentication no/g' /etc/ssh/ssh_config