I will be preparing for the RHCE exam on rhel6 this year and wanted to make a blog to track my progress. My main study tool will be Michael Jang's RHCE certification guide starting at chapter 10. In the course of this study, I also intend to complete a lab build that's outlined in the following post on reddit.
https://www.reddit.com/r/linuxadmin/comments/2s924h/how_did_you_get_your_start/
As I go through each step of the lab buildout, I'll try my best to document with pictures how to work with each application/service, mainly for the sake of remembering what was done/how to configure the services come exam time.
"
This is what I tell people to do, who ask me "how do I learn to be a Linux sysadmin?".
1) Set up a KVM hypervisor.
2) Inside of that KVM hypervisor, install a Spacewalk server. Use CentOS
6 as the distro for all work below. (For bonus points, set up errata
importation on the CentOS channels, so you can properly see security
update advisory information.)
3) Create a VM to provide named and dhcpd service to your entire
environment. Set up the dhcp daemon to use the Spacewalk server as the
pxeboot machine (thus allowing you to use Cobbler to do unattended OS
installs). Make sure that every forward zone you create has a reverse
zone associated with it. Use something like "internal.virtnet" (but
not ".local") as your internal DNS zone.
4) Use that Spacewalk server to automatically (without touching it)
install a new pair of OS instances, with which you will then create a
Master/Master pair of LDAP servers. Make sure they register with the
Spacewalk server. Do
not allow anonymous bind, do
not use unencrypted LDAP.
5) Reconfigure all 3 servers to use LDAP authentication.
6) Create two new VMs, again unattendedly, which will then be Postgresql
VMs. Use pgpool-II to set up master/master replication between them.
Export the database from your Spacewalk server and import it into the
new pgsql cluster. Reconfigure your Spacewalk instance to run off of
that server.
7) Set up a Puppet Master. Plug it into the Spacewalk server for
identifying the inventory it will need to work with. (Cheat and use
ansible for deployment purposes, again plugging into the Spacewalk
server.)
8 Deploy another VM. Install iscsitgt and nfs-kernel-server on it. Export a LUN and an NFS share.
9) Deploy another VM. Install bakula on it, using the postgresql cluster
to store its database. Register each machine on it, storing to
flatfile. Store the bakula VM's image on the iscsi LUN, and every other
machine on the NFS share.
10) Deploy two more VMs. These will have httpd (Apache2) on them. Leave essentially default for now.
11) Deploy two
more VMs. These will have tomcat on them. Use
JBoss Cache to replicate the session caches between them. Use the httpd
servers as the frontends for this. The application you will run is
JBoss Wiki.
12) You guessed right, deploy another VM. This will do iptables-based
NAT/round-robin loadbalancing between the two httpd servers.
13) Deploy another VM. On this VM, install postfix. Set it up to use a
gmail account to allow you to have it send emails, and receive messages
only from your internal network.
14) Deploy another VM. On this VM, set up a Nagios server. Have it use
snmp to monitor the communication state of every relevant service
involved above. This means doing a "is the right port open" check,
and a "I got the right kind of response" check
and "We still have filesystem space free" check.
15) Deploy another VM. On this VM, set up a syslog daemon to listen to
every other server's input. Reconfigure each other server to send their
logging output to various files
on the syslog server. (For extra credit, set up logstash or kibana or greylog to parse those logs.)
16) Document every last step you did in getting to this point in your brand new Wiki.
17) Now go back and create Puppet Manifests to ensure that every last
one of these machines is authenticating to the LDAP servers, registered
to the Spacewalk server, and backed up by the bakula server.
18 Now go back, reference your documents, and set up a Puppet Razor
profile that hooks into each of these things to allow you to recreate,
from scratch, each individual server.
19) Destroy every secondary machine you've created and use the above
profile to recreate them, joining them to the clusters as needed.
20) Bonus exercise: create three more VMs. A CentOS 5, 6, and 7 machine. On
each
of these machines, set them up to allow you to create custom RPMs and
import them into the Spacewalk server instance. Ensure your Puppet
configurations work for all three and produce like-for-like behaviors.
Do these things and you will be fully exposed to every aspect of
Linux Enterprise systems administration. Do them well and you will have
the
technical expertise required to seek "Senior" roles. If
you go whole-hog crash-course full-time it with no other means of
income, I would expect it would take between 3 and 6 months to go from
"I think I'm good with computers" to achieving all of these -- assuming
you're not afraid of IRC and google (and have neither friends nor
family ...)."
