B Updated dhclient Script
The dhclient-exit-hook-set-hostname.sh-ol8 is intended for use on Oracle Linux instances on Oracle Cloud Infrastructure
that have been upgraded from Oracle Linux 7 to Oracle Linux 8. This script includes code for the proper handling of
connectivity to those upgraded instances.
#!/bin/bash
#
# Copyright (C) 2022 Oracle. All rights reserved.
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation, version 2. This program is distributed in the hope that it will
# be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details. You should have received a copy of the GNU
# General Public License along with this program; if not, write to the Free
# Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
# 021110-1307, USA.
log () {
logger -t "${0##*/}" "$*"
}
log "set hostname, /etc/hosts, /etc/resolv.conf begin $(date):"
OPC_CONF="/etc/oci-hostname.conf"
# import the oci-hostname configuration info
if [ -f $OPC_CONF ]; then
. $OPC_CONF
fi
# ER-28862654 - Add custom header text to /etc/resolv.conf
if ! grep -q "docs.cloud.oracle.com" /etc/resolv.conf; then
sed -i '1i; Any changes made to this file will be overwritten whenever the\
; DHCP lease is renewed. To persist changes you must update the\
; /etc/oci-hostname.conf file. For more information see\
;[https://docs.cloud.oracle.com/iaas/Content/Network/Tasks/managingDHCP.htm#notes]\
;' /etc/resolv.conf
fi
function retry_command()
{
retry_attempts=30
retry_interval_sec=2
while [ "$retry_attempts" -gt 0 ]; do
command_success=true
"$@" || { command_success=false; }
if [ "$command_success" == false ]; then
(( retry_attempts-- ))
log "Error occurred running command $@. Will retry in $retry_interval_sec seconds"
sleep $retry_interval_sec
else
log "Successfully executed the command $@"
break
fi
done
# Check if issue running command still existed after all retry_attempts
if [ "$command_success" == false ]; then
log "ERROR: failed to execute command '$@' (Retried $retry_attempts times)"
return 1
fi
}
#Usage: add_entries <file name> <keyword> <an array of the corresponding values for the keyword>
#We pass array by name so if the array name is 'arr', pass it as 'arr' instead of $arr
#This function can be used to add entries to files with a mapping format.
#For example, /etc/hosts has <ip> mapped to <fqdn/host alias>
#The function checks to see if a line containing the given 'keyword' is in the file
#If so, we check the given array of values against the existing values for the keyword in that line.
#Append the values specified in the array to the line if it doesn't already exist.
#If the file does not contain a line with the given keyword,
#the function will add a new line with the given keyword mapped to all values in the given array.
function add_entries()
{
local file=${1}
local keyword=${2}
local values=$3[@]
values=("${!values}")
if ! grep -qw "^$keyword" $file; then
log "Line with '$keyword' not found in $file"
new_entry="$keyword"
for value in "${values[@]}"
do
new_entry="$new_entry $value"
done
log "Adding '$new_entry' to $file"
echo "$new_entry" >> $file
else
log "Found line with '$keyword'"
target_line=$(grep -w "^$keyword" $file)
for value in "${values[@]}"
do
#First case needs spaces around $value to make sure it's not the prefix or suffix of another value
#Second case checks if $value is at the end of the line
if [[ $target_line == *" $value "* ]] || [[ $target_line == *" $value" ]]; then
log "'$value' already exists in line"
else
log "Adding '$value' to line"
sed -i "s/^\<$keyword\>.*$/& $value/g" $file
fi
done
fi
}
# This function updates the hostname
# Arguments:
# Arg1 -- OS version information to set hostname accordingly
# Arg2 -- Hostname that needs to be set
function update_hostname()
{
local os_version=${1}
local new_host_name=${2}
log "Updating hostname"
# 1. run hostname command
if [ $os_version -eq 6 ]; then
# use short hostname for /etc/sysconfig/network
# https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Installation_Guide/sn-Netconfig-x86.html
new_host_name_config="HOSTNAME=$new_host_name"
log "Update /etc/sysconfig/network with new host name $new_host_name_config"
if grep --quiet '^HOSTNAME=' /etc/sysconfig/network; then
log "HOSTNAME exists in /etc/sysconfig/network. Updating its value"
sed -i "s/^HOSTNAME=.*$/$new_host_name_config/g" /etc/sysconfig/network
else
log "Adding HOSTNAME to /etc/sysconfig/network"
echo "$new_host_name_config" >> /etc/sysconfig/network
fi
log "Running hostname command: hostname $new_host_name"
hostname $new_host_name
elif [ $os_version -eq 7 ]; then
log "Running hostnamectl command: hostnamectl set-hostname $new_host_name"
hostnamectl set-hostname $new_host_name >> $log_file 2>&1
elif [ $os_version -eq 8 ]; then
systemctl is-active --quiet NetworkManager
nm_status=$?
if [ $nm_status -eq 0 ]; then
log "Running nmcli command: nmcli general hostname $new_host_name"
nmcli general hostname $new_host_name
else
log "Running hostnamectl command: hostnamectl set-hostname $new_host_name"
hostnamectl set-hostname $new_host_name
fi
fi
}
# This function updates /etc/hosts and /etc/resolv.conf
# Arguments:
# Arg1 -- new IP address
# Arg2 -- new hostname of the system
function update_hosts_resolv()
{
local new_ip_address=${1}
local new_host_name=${2}
# Retry params
fqdn_success=1
retries=12
# Remove old entry from /etc/hosts so that we avoid getting
# stale information from ipcalc.
# First though, save the entries for
# restoration if ipcalc encounters failures.
old_vals=$(grep "^$new_ip_address" /etc/hosts)
old_fqdn=$(echo $old_vals | awk -F " " '{print $2}')
old_host_name=$(echo $old_vals | awk -F " " '{print $3}')
log "Pre-existing fqdn is $old_fqdn and hostname is $old_host_name"
# Now remove old entry
sed -i "/^\<$new_ip_address\>.*$/d" /etc/hosts
while [[ $fqdn_success -ne 0 ]] && [[ $retries -ne 0 ]]; do
# Get fqdn
fqdn=$(retry_command ipcalc -h $new_ip_address)
if [[ "$fqdn" != *.*.*.*.* ]]; then
# DNS can take upto 120 seconds to return info. Retry as long.
sleep 10
(( retries-- ))
else
fqdn_success=0
fi
done
if [ $fqdn_success -ne 0 ]; then
log "ERROR: ipcalc unsuccessful despite multiple retries for 120 seconds"
# Restore previously existing hostname entry but first:
# Check for existing exact matches of hostname and delete them, if any.
sed -i -e "/[[:space:]]\<$old_host_name\>[[:space:]\.]/d; /[[:space:]]\<$old_host_name\>$/d" /etc/hosts
fqdn=${fqdn#HOSTNAME=}
echo "fqdn=$fqdn" >> $log_file
old_host_values=("$old_fqdn" "$old_host_name")
# Pre-existing FQDN is null for the first boot.
if [ -z "$old_fqdn" ]; then
echo "Pre-existing fqdn is . Skip updating /etc/hosts" >> $log_file
else
add_entries "/etc/hosts" "$new_ip_address" old_host_values
fi
else
# ipcalc returns HOSTNAME=xxxx, need to remove "HOSTNAME="
fqdn=${fqdn#HOSTNAME=}
# get subnet_domain_name
subnet_domain_name=${fqdn#$new_host_name.}
# verify that the subnet domain is valid, we expect it is of the
# form <subnet-name>.<vcn-name>.<oraclevcn>.<com>
if [[ "$subnet_domain_name" != *.*.*.* ]]; then
log "ERROR: invalid subnet domain name '$subnet_domain_name'."
else
# get vcn domain name - everything after the first dot in the subnet domain name
vcn_domain_name=${subnet_domain_name#*.}
log "fqdn=$fqdn"
log "subnet_domain_name=$subnet_domain_name"
log "vcn_domain_name=$vcn_domain_name"
# 2. Update /etc/hosts if needed
# Check for existing exact matches of hostname and delete them, if any.
sed -i -e "/[[:space:]]\<$new_host_name\>[[:space:]\.]/d; /[[:space:]]\<$new_host_name\>$/d" /etc/hosts
new_host_values=("$fqdn" "$new_host_name")
# Pass array by name
add_entries "/etc/hosts" "$new_ip_address" new_host_values
# 3. Update /etc/resolv.conf
# This is a temp fix till we have a resolution for a proper dhcp response
new_search_domains=("$subnet_domain_name" "$vcn_domain_name")
add_entries "/etc/resolv.conf" "search" new_search_domains
echo -e "[main]\ndns = none\n" > /run/NetworkManager/conf.d/10-oci-dhclient.conf
fi
fi
}
# This function updates /etc/resolv.conf
# Arguments:
# Arg1 -- new IP address
# Arg2 -- new hostname of the system
function update_resolv()
{
local new_ip_address=${1}
local new_host_name=${2}
# Retry params.
retries=12
fqdn_success=1
while [[ $fqdn_success -ne 0 ]] && [[ $retries -ne 0 ]]; do
# Since the hostname might have been changed in /etc/hosts and we're not
# updating it, only using ipcalc might give us stale hostname information.
# To get the DNS provided hostname, use host and compare it with ipcalc's
# generated version. If they don't match use the one from host.
host_name=$(retry_command host $new_ip_address | awk -F " " '{print $5}')
ipcalc_name=$(retry_command ipcalc -h $new_ip_address)
if [[ "$ipcalc_name" != *.*.*.*.* ]] || [[ "$host_name" != *.*.*.*.* ]]; then
# DNS can take up to 120 seconds to return info. Retry as long.
sleep 10
(( retries-- ))
else
fqdn_success=0
fi
done
if [[ $fqdn_success -ne 0 ]]; then
log "ERROR: ipcalc and host commands failed " \
log "despite multiple retries for 120 seconds."
else
# ipcalc returns HOSTNAME=xxxx, need to remove "HOSTNAME="
ipcalc_name=${ipcalc_name#HOSTNAME=}
log "ipcalc returned hostname: $ipcalc_name"
# host substring will have a "." at the end. Drop it
host_name=${host_name%?}
log "host returned hostname: $host_name"
use_ipcalc_hostname=0
if [ "$host_name" = "$ipcalc_name" ]; then
# either one will do
fqdn=$ipcalc_name
else
# Likely that ipcalc has a user changed hostname.
# This will not match the new_host_name one.
# Use the one from host. But before that confirm
# that host has returned a valid name.
if [[ "$host_name" != *.*.*.*.* ]]; then
log "Invalid hostname $host_name from host command"
fqdn=$ipcalc_name
# Need an additional check here for the host_name
# being identical to the new_host_name as the user
# could have changed the /etc/host host_name
# entry which would not match the dhclient one.
ipcalc_host_name=$(echo $ipcalc_name | awk -F "." '{print $1}')
if [[ "$ipcalc_host_name" != "$new_host_name" ]]; then
log "ipcalc returned host $ipcalc_host_name"
log "dhclient returned host $new_host_name"
log "Using ipcalc returned hostname"
use_ipcalc_hostname=1
fi
else
fqdn=$host_name
fi
fi
# get subnet_domain_name
if [[ "$use_ipcalc_hostname" -eq 1 ]]; then
subnet_domain_name=${fqdn#$ipcalc_host_name.}
else
subnet_domain_name=${fqdn#$new_host_name.}
fi
# verify that the subnet domain is valid, we expect it is of the
# form <subnet-name>.<vcn-name>.<oraclevcn>.<com>
if [[ $subnet_domain_name != *.*.*.* ]]; then
log "WARNING: invalid subnet domain name '$subnet_domain_name' seen."
else
# get vcn domain name - everything after the first dot in the subnet domain name
vcn_domain_name=${subnet_domain_name#*.}
log "fqdn=$fqdn"
log "subnet_domain_name=$subnet_domain_name"
log "vcn_domain_name=$vcn_domain_name"
# Update /etc/resolv.conf
new_search_domains=("$subnet_domain_name" "$vcn_domain_name")
add_entries "/etc/resolv.conf" "search" new_search_domains
echo -e "[main]\ndns = none\n" > /run/NetworkManager/conf.d/10-oci-dhclient.conf
fi
fi
}
# This function adds NM_CONTROLLED=no entry to the primary interface config file
# So that network manger does not take cotrol when installed.
# Arguments:
# Arg1 -- primary_ip
function disable_NMcontrol()
{
local primary_ip=${1}
# find the primary interface
primary_if=$(ifconfig | grep -B1 $primary_ip | head -n1 | awk -F '[: ]' '{print $1}')
# generate the primary interface's ifconfig filepath.
cfg_file="/etc/sysconfig/network-scripts/ifcfg-${primary_if}"
# check if the file is present.
if [ ! -f $cfg_file ]; then
log "$cfg_file not found, skip NM_CONTROLLED setting."
return
fi
# check if the keyword is present or not
if ! grep -qw "^NM_CONTROLLED" $cfg_file; then
# append the line..
echo "NM_CONTROLLED=no" >> $cfg_file
else
# modify the line
sed -i "s/^\<NM_CONTROLLED\>.*$/NM_CONTROLLED=no/g" $cfg_file
fi
}
os_version=0
if [ -f /etc/os-release ]; then
os_string=$(grep -w VERSION /etc/os-release | awk -F "\"" '{print $2}')
log "INFO: Obtained $os_string from /etc/os-release"
if [[ "$os_string" == "8."* || "$os_string" == "8"* ]]; then
os_version=8
elif [[ "$os_string" == "7."* || "$os_string" == "7"* ]]; then
os_version=7
elif [[ "$os_string" == "6."* ]]; then
os_version=6
fi
fi
if [ $os_version == 0 ]; then
log "INFO: Getting OS version via uname -mrs"
kernel_version=$(uname -mrs)
if [[ "$kernel_version" == *"el8"* ]]; then
os_version=8
elif [[ "$kernel_version" == *"el7"* ]]; then
os_version=7
elif [[ "$kernel_version" == *"el6"* ]]; then
os_version=6
fi
fi
if [ $os_version == 0 ]; then
log "ERROR: Could not obtain valid OS version. Exiting.."
exit 1
fi
# OL8 use NetworkManager. DHCP does not provide a reason.
if [[ "$os_version" -ne 8 ]]; then
log "$(date): Script Reason: $reason"
else
log "$(date): Script Reason: NM-controlled system"
fi
# For non-OL8 OSs get the primary vnic ip only if interface has been
# initialized.
# Ref: https://www.isc.org/wp-content/uploads/2018/02/dhcp44cscript.html#PREINIT
if [ "$os_version" == 8 -o "$reason" != "PREINIT" ]; then
primary_ip=$(retry_command curl -H "Authorization: Bearer Oracle" http://169.254.169.254/opc/v2/vnics/ -sf | jq -r '.[0] | .privateIp')
log "$(date): Primary IP obtained: $primary_ip"
fi
# This script is invoked whenever dhclient is run.
# For non-ol8 instances, We want to skip hostname update if
# $new_ip_address != $primary_ip
# so we don't run this for all interfaces
# For ol8, with the use of NM, we don't get information on the
# new_ip_address, therefore we just use the primary_ip each time.
if [ -z "$primary_ip" ]; then
log "Skip updating hostname because primary ip is empty."
elif [[ "$os_version" -ne 8 ]] && [[ "$new_ip_address" != "$primary_ip" ]]; then
log "Skip updating hostname because this was not invoked for the primary vnic"
else
if [ $os_version -ne 8 ]; then
# For non-ol8, add NM_Controlled="no" to primary network interface
# configuration file
disable_NMcontrol $primary_ip
# reason why this hook was invoked. It is set by dhclient script when
# the OS is non-ol8
log "reason=$reason"
# https://linux.die.net/man/8/dhclient-script
if [ "$reason" = "BOUND" ] || [ "$reason" = "RENEW" ] || [ "$reason" = "REBIND" ] || [ "$reason" = "REBOOT" ]; then
log "os version = $os_version"
#These variables are set by dhclient script
log "new_ip_address=$new_ip_address"
log "new_host_name=$new_host_name"
log "new_domain_name=$new_domain_name"
else
log "Not updating because reason=$reason"
fi
fi
if [[ $PRESERVE_HOSTINFO -eq 2 ]]; then
log "Skip updating hostname, /etc/hosts and /etc/resolv.conf"
log "as per PRESERVE_HOSTINFO=${PRESERVE_HOSTINFO} setting"
return 0
fi
#Retrieve hostname from metadata if its empty
if [ -z $new_host_name ]; then
new_host_name=$(retry_command curl -sf -H "Authorization: Bearer Oracle" http://169.254.169.254/opc/v2/instance/ | jq '.hostname' -r)
fi
# Will get retrieved for ol8 since we do not have DHCP provided vars.
if [ -z $new_ip_address ]; then
new_ip_address=$(retry_command curl -H "Authorization: Bearer Oracle" http://169.254.169.254/opc/v2/vnics/ -sf | jq -r '.[0] | .privateIp')
fi
if [ -z $new_host_name ]; then
echo "ERROR: new_host_name is empty after retrieving it from metadata json. Exiting."
exit_status=1
else
log "new_ip_address=$primary_ip"
if [[ $PRESERVE_HOSTINFO -eq 0 ]]; then
# update the hostname with new hostname
update_hostname $os_version $new_host_name
# update hosts and resolv conf files
update_hosts_resolv $new_ip_address $new_host_name
elif [[ $PRESERVE_HOSTINFO -eq 1 ]]; then
log "Skip updating hostname as per"
log "PRESERVE_HOSTINFO=${PRESERVE_HOSTINFO} setting"
# update hosts and resolv conf files
update_hosts_resolv $new_ip_address $new_host_name
elif [[ $PRESERVE_HOSTINFO -eq 3 ]]; then
log "Skip updating hostname and /etc/hosts as per"
log "PRESERVE_HOSTINFO=${PRESERVE_HOSTINFO} setting"
log "Updating subnet in /etc/resolv"
# update resolv conf file alone
update_resolv $new_ip_address $new_host_name
fi
fi
fi
log "sethostname, /etc/hosts, /etc/resolv.conf END"