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====== Diskless Debian, network boot ======

References: [[http://blog.tremily.us/posts/Abax/nfs_root/]]

  * Install pxe and the tftp server:

  sudo apt-get install syslinux tftpd-hpa isc-dhcp-server nfs-kernel-server unionfs-fuse

  * Configure the dhcp server. Edit file /etc/dhcp/dhcpd.conf and edit the following lines:

  option domain-name "example.loc";
  option domain-name-servers dns1ip, dns2ip;

  * And add the following lines ...

  subnet 192.168.2.0 netmask 255.255.255.0 {
   range 192.168.2.100 192.168.2.200;
   option routers 192.168.2.1;
   option broadcast-address 192.168.2.255;
   default-lease-time 600;
   max-lease-time 7200;
  }
  
  host diskless_client {
     hardware ethernet mac-address;
     fixed-address 192.168.2.10;
     filename "pxelinux.0";
     next-server 192.168.2.1;
     option subnet-mask 255.255.255.0;
     option broadcast-address 192.168.2.255;
     option routers 192.168.2.1;
  }

  * Restart dhcp server:

  sudo /etc/init.d/isc-dhcp-server restart

  * Configure the tftp files for network boot:

  sudo cp /usr/lib/syslinux/pxelinux.0 /srv/tftp/
  sudo mkdir pxelinux.cfg
  cd /srv/tftp/pxelinux.cfg/
  
  * Create and edit a file called diskless_client and put the following inside:

  PROMPT 1
  DEFAULT diskless_client
  TIMEOUT 10
  LABEL diskless_client
  #skipping one of the dhcp steps: ip=<ip>:<server-ip>:<gateway-ip>:<netmask>::eth0:
  # It is possible to use ip=:::arcoslab02:amy:eth6:dhcpi but it may be slow.
  # Also, eth6 must be the card that receives DHCP answers, even when
  # the trunking to the outside is not set up yet.
  # It is not possible to put a name in nfsroot.
  
        kernel diskless_client/vmlinuz-3.2.0-3-amd64
        append boot=nfs root=/dev/nfs nfsroot=192.168.17.1:/ ip=dhcp initrd=diskless_client/initrd.img-3.2.0-3-amd64 rw rootdelay=10 vga=extended init=/etc/init.d/init_diskless_client --
  
  #break=mount

  * Make a link to default

  sudo ln -s diskless_client default

  * Copy the kernel and initrd images to the tftp directory:

  sudo mkdir /srv/tftp/diskless_client/
  sudo cp /boot/vmlinuz-3.2.0-3-amd64 /srv/tftp/diskless_client/
  sudo cp /boot/initrd.img-3.2.0-3-amd64 /srv/tftp/diskless_client/

  * Create a directory and some files for the system files that will be different on the diskless_client computer. This will later be mounted on the diskless_client on top of the root filesystem using unionfs.

  sudo mkdir /unionfsfstab

  sudo mkdir -p /unionfs/common/etc
  sudo mkdir -p /unionfs/common/var
  sudo mkdir -p /unionfs/host
  sudo mkdir -p /unionfs/hosts/diskless_client/etc/apache2/sites-enabled
  sudo mkdir -p /unionfs/hosts/diskless_client/etc/dhcp/fstab

  sudo mkdir -p /unionfs/hosts/diskless_client/etc/init.d/
  sudo mkdir -p /unionfs/hosts/diskless_client/etc/network
  sudo mkdir -p /unionfs/hosts/diskless_client/etc/rc2.d/
  sudo mkdir -p /unionfs/hosts/diskless_client/etc/rc6.d/
  sudo mkdir -p /unionfs/hosts/diskless_client/etc/rcS.d/
  sudo mkdir -p /unionfs/hosts/diskless_client/var
  sudo mkdir -p /unionfs/union/etc
  sudo mkdir -p /unionfs/union/var
  sudo touch /unionfs/common/etc/README
  sudo touch /unionfs/common/var/README
  sudo touch /unionfs/host/README
  sudo touch /unionfs/hosts/diskless_client/etc/README
  sudo touch /unionfs/union/etc/README
  sudo touch /unionfs/union/var/README
  sudo touch /unionfs/hosts/diskless_client/etc/apache2/sites-enabled/000-default
  sudo touch /unionfs/hosts/diskless_client/etc/apache2/sites-enabled/default-ssl
  sudo touch /unionfs/hosts/diskless_client/etc/apache2/sites-enabled/dokuwiki
  sudo touch /unionfs/hosts/diskless_client/etc/apache2/sites-enabled/homes
  sudo touch /unionfs/hosts/diskless_client/etc/exports
  sudo touch /unionfs/hosts/diskless_client/etc/init.d/apache2
  sudo touch /unionfs/hosts/diskless_client/etc/init.d/isc-dhcp-server
  sudo touch /unionfs/hosts/diskless_client/etc/init.d/nfs-kernel-server
  sudo touch /unionfs/hosts/diskless_client/etc/init.d/tftp-hpa
  sudo touch /unionfs/hosts/diskless_client/etc/rc6.d/K03sendsigs
  

  * Also edit some of the following files with:

/unionfs/hosts/diskless_client/etc/fstab

  192.168.2.1:/root     /root    nfs     rw,nfsvers=3,hard,intr,bg,timeo=600,nolock,rsize=32768,wsize=32768,noatime      0       0
  192.168.2.1:/home     /home    nfs     rw,nfsvers=3,hard,intr,bg,timeo=600,nolock,rsize=32768,wsize=32768,noatime      0       0
  tmpfs                  /tmp     tmpfs   defaults        0       0
  /unionfs/union/etc     /etc     none    ro,bind         0       0

/unionfs/hosts/diskless_client/etc/hostname

  arcoslab02


/unionfs/hosts/diskless_client/etc/hosts

  127.0.0.1 localhost
  127.0.1.1 example2.com example2

/unionfs/hosts/diskless_client/etc/network/interfaces

  auto lo 
  iface lo inet loopback


/unionfs/hosts/diskless_client/etc/syslog.conf

  #send everything to diskless_server
  *.*;local4.!* /var/log/messages
  *.*;local4.!* @diskless_server_ip
  local4.*      /var/log/ipmi

  * Export root file system as read-only (to avoid damage by the other computer) and others as read-write using nfs:

  #diskless_client
  /    192.168.2.23(ro,insecure,async,no_subtree_check,no_root_squash,insecure_locks)
  /root   192.168.2.23(rw,insecure,async,no_subtree_check,no_root_squash,insecure_locks)
  /home   192.168.2.23(rw,insecure,async,no_subtree_check,no_root_squash,insecure_locks)
  /unionfs        192.168.2.23(rw,insecure,async,no_subtree_check,no_root_squash,insecure_locks)

  * In the server computer create a file called /etc/init_diskless_client with :

  #!/bin/sh -x
  NFS_SERV="192.168.2.1"
  NFS_OPT="-otcp,nfsvers=3,hard,intr,bg,timeo=600,nolock,rsize=32768,wsize=32768"
  
  FUSE_OPT="-o default_permissions -o allow_other -o use_ino -o nonempty -o suid"
  UNION_OPT="-o cow -o noinitgroups"
  
  UPATH="/unionfs"
  UBIN="/usr/bin/unionfs-fuse"
  
  ulimit -n 16384
  
  #This tmpfs is needed, because mount and others need a temporary place to write
  #consider changing this to a permanent place over NFS?  Could fill RAM
  mount -n -t tmpfs tmpfs /tmp
  
  ifconfig lo 127.0.0.1
  
  #specific directory
  mount -n -t nfs $NFS_OPT ${NFS_SERV}:${UPATH}/hosts/diskless_client ${UPATH}/host
  
  #function to combine a directory from the read-only root directory (/),
  #with a specific unionfs for this host that is writable
  unionmount()
  {
        dir=$1
        mkdir -p ${UPATH}/host/$dir  #if not existant, create dir
        mount -n --bind /$dir $UPATH/common/$dir  #mount the original read-only dir to common
        host="${UPATH}/host/${dir}=RW"
        common="$UPATH/common/${dir}=RO"
        #combine the two directories into a unionfs
        $UBIN $FUSE_OPT $UNION_OPT ${host}:${common} $UPATH/union/$dir
        #replace the mount in /$dir with the newly created combination
        mount -n --bind $UPATH/union/$dir /$dir
  }
  
  #same as the previous function, just make the directory read-only at the end
  unionmount_ro()
  {
        dir=$1
        unionmount $dir
        mount -n -o remount,ro /$dir
  }
  
  #which directories will get the overlay of the unionfs:
  unionmount etc
  cat /proc/mounts > /etc/mtab
  mount -n -o remount,ro $UPATH/union/etc
  mount -n -o remount,ro /etc
  
  #sleep 4                                                                        
  
  unionmount var
  
  mount -t nfs -a
  #/etc/init.d/chrony start                                                       
  /etc/init.d/ssh start
  
  #exec /bin/bash                                                                 
  exec /sbin/init


  * Change permissions of this file to executable:

  sudo chmod +x /etc/init.d/diskless_client

~~DISCUSSION~~