Update all instances of IP address on a server

Question

We currently have a dynamically provided IP address and are switching over to a static ip address. As such, I need to change the IP address on our 3 LAMP servers. These servers also run bind9 for DNS and postfix/dovecot for email. (MySQL is actually running as a Percona DB cluster which may be irrelevant.)

I think I have a good strategy, but want to check my logic with others who may have done this successfully before.

The concept is to stop all web, database, and mail services on each machine one at a time, pushing traffic to one of the two remaining servers, and run the following script to replace the old IP address with the new IP address, then reboot the server and attempt to push traffic back to it then proceed with the next server in the cluster if all goes well.

I used grep -r to find instances of the old ip address in the system and need to make sure that I'm not missing anything important that needs to be considered.

find /etc/bind -type f -print0 | xargs -0 sed -i 's/old.ip.address/new.ip.address/g'
find /etc/postfix -type f -print0 | xargs -0 sed -i 's/old.ip.address/new.ip.address/g'
find /etc/apache2 -type f -print0 | xargs -0 sed -i 's/old.ip.address/new.ip.address/g'
find /etc/postfix -type f -print0 | xargs -0 sed -i 's/old-ip-address/new-ip-address/g'
find /etc/bind -type f -print0 | xargs -0 sed -i 's/rev.address.ip.old/rev.address.ip.new/g'

As a point of clarification, grep -r found the IP address references in the /etc/bind/zones tables, the /etc/postfix configuration files, and the /etc/apache2 config file. The IP address separated by hyphens was also found in the postfix config files. The reverse IP address was also found in a /etc/bind/named.conf.local file and will also need to be replaced.

Can anyone see if I may be missing something here? I'm doing this in a production environment...not the most ideal of circumstances, of course.

Answer 1

Sorry all. Looks like I let this get stale after finding the solution. For posterity's sake, here's what seems to be working at this point:

$ORIGIN example.com.
$TTL 12H
; @ symbol represents example.com.
@   12H IN  SOA ns1.example.com.    [email protected]. (
2015062954 ;serial
30M ;refresh
2M ;retry
2W ;expire
1D ;minimum TTL
)
NS  ns1.example.com.
NS  ns2.example.com.
MX  10  mail.example.com.
IN  A   99.101.XXX.XXX
IN  TXT "v=spf1 a mx ip4:99.101.XXX.XXX ~all"
IN  SPF "v=spf1 a mx ip4:99.101.XXX.XXX -all"
ns1 IN  A   99.101.XXX.XXX
ns2 IN  A   99.101.XXX.XXX
mail    IN  A   99.101.XXX.XXX
IN  TXT "v=spf1 a mx ip4:99.101.XXX.XXX ~all"
IN  SPF "v=spf1 a mx ip4:99.101.XXX.XXX -all"
www IN  A   99.101.XXX.XXX
dev IN  A   99.101.XXX.XXX
demo    IN  A   99.101.XXX.XXX
webconf IN  A   99.101.XXX.XXX
stats   IN  A   99.101.XXX.XXX

Answer 2

While the idea of using a find piped to an xargs sounds reasonable, I would take my 15 years of experience and tell you that is a bad idea. I would propose:

1. identify those services running on the boxes that are important (your find command works great here)
2. identify those files important to each of those services where address is defined
3. back up those files (cp to .orig works nicely)
4. create new files that contain your new addresses

This way you have a fast transition with:

cp somefile.new somefile

and a fast backout with:

cp somefile.orig somefile

Additionally, I would expect that the zones files contain actual DNS entries, so changing them is fine, but you'll probably need to reload named for those changes to take effect. Same goes for postfix, you'll want to postfix reload those as well.

EDIT (I haven't taken the time to actually load this zone, but it looks reasonably correct):

$ORIGIN example.com. 
$TTL 12H @  IN  SOA ns1.example.com.    [email protected]. ( 
                2015062660 ; 
                30M ;refresh 
                2M ;retry 
                2W ;expire 
                1D ;minimum TTL 
                )   

        IN  NS  ns1.example.com. 
        IN  NS  ns2.example.com. 

        IN  A   99.101.XXX.X 

example.com.    IN  MX  10  mail.example.com. 
mail        IN  A   99.101.XXX.X 
        IN  TXT     "v=spf1 a mx ip4:99.101.XXX.X ~all

ns1     IN  A   99.101.XXX.X 
ns2     IN  A   99.101.XXX.X 
www     IN  CNAME   example.com. 
dev         IN  CNAME   example.com. 
demo        IN  CNAME   example.com. 
webconf     IN  CNAME   example.com. 
stats       IN  CNAME   example.com. 

EDIT: glue records