Linux System Administration Recipes A Problem-Solution Approach

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CHAPTER 3 ■ MONITORING AND UPDATINGdn: cn=server1,ou=Hosts,dc=example,dc=comadd: objectClassobjectClass: puppetClient-add: puppetclasspuppetclass: serverdn: cn=desktop1,ou=Hosts,dc=example,dc=comadd: objectClassobjectClass: puppetClient-add: puppetclasspuppetclass: desktopAdd all the other hosts you want to use with this system. Authenticate as the LDAP admin user, andrun the modification:kinit ldapadm; ldapmodify -f puppet.ldifFinally, in /etc/puppet/puppetmasterd.conf on the Puppet server, add the following:[ldap]ldapnodes = trueldapserver = ldapserver.example.comldapbase = dc=example,dc=comand restart the puppetmaster.■ Note If you’re changing the puppetmaster config or any other Puppet setup stuff, it can be useful to stop therunning puppetmaster process and restart it interactively with the verbose option: puppetmasterd --verbose.This helps a lot with debugging.3-16. Puppet: Using Facter and TemplatesAnother useful aspect of Puppet is that it works together with a piece of software called Facter. Factersets up per-host variables (such as hostname, IP address, and operating system) automatically. So, youcan apply types, configure resources, and make specific changes according to these facts, or you cancreate your own facts.To see the full lists of the facts provided by default, type facter at the command line.You can refer to these facts within Puppet with $factname. There are two important uses for thesefacts:• To create conditional structures• To use in templates88Download at WoweBook.Com
CHAPTER 3 ■ MONITORING AND UPDATINGThere are three types of conditionals in Puppet:• Selectors, which are used within a statement:package {"krb-clients":ensure => $operatingsystem ? {ubuntu => absent,debian => installed,default => undef};}Here, if the $operatingsystem fact is set to ubuntu, the package is not installed; ifit’s set to debian, it is installed. The default is to not do anything at all. Note thelack of comma on the final line.• case statements provide a way of conditionally applying classes:case $operatingsystem {ubuntu: { include ubuntu }debian: { include debian }default: { include basic }}In this snippet, the class specific to each operating system is included dependingagain on the value of the $operatingsystem fact. Multiple conditions can bespecified using a comma.• A simple if/else structure:if $needexample {file { "/usr/local/example": ensure => present }}else {file { "/usr/local/test": ensure => present }}Currently it is possible to determine only whether the variable is or is not set, notto distinguish between particular values of a variable—for that, you must use thecase or selector statements.A template uses Ruby to put variables into a source file. In other words, it’s like providing a centralfile that can vary machine by machine.A good example of using a fact in a template is to set an ipchains policy. The following file,iptables.erb (ERB is the Ruby template syntax), uses $ipaddress:*filter:INPUT DROP [0:0]:FORWARD DROP [0:0]:OUTPUT ACCEPT [0:0]-A INPUT -d 127.0.0.0/255.0.0.0 -i ! lo -p tcp -j DROP-A INPUT -d -m state --state RELATED,ESTABLISHED -j ACCEPT-A INPUT -i lo -j ACCEPT89Download at WoweBook.Com
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Contents■About the Author .......
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■ CONTENTS3-7. Writing a Nagios P
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■ CONTENTS■Chapter 8: Using the
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■ CONTENTSAbout the Author■Juli
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■ CONTENTSAcknowledgmentsMany tha
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■ CONTENTSIntroductionThis book i
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■ INTRODUCTIONDownloading the Cod
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C H A P T E R 1■ ■ ■Saving Yo
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CHAPTER 1 ■ SAVING YOURSELF EFFOR
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C H A P T E R 2■ ■ ■Centraliz
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CHAPTER 2 ■ CENTRALIZING YOUR NET
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CHAPTER 6 ■ SECURING YOUR SYSTEMS
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C H A P T E R 7■ ■ ■Working w
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CHAPTER 7 ■ WORKING WITH APACHEOn
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CHAPTER 7 ■ WORKING WITH APACHEdi
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CHAPTER 7 ■ WORKING WITH APACHE4.
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CHAPTER 7 ■ WORKING WITH APACHE
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CHAPTER 7 ■ WORKING WITH APACHEAl
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CHAPTER 7 ■ WORKING WITH APACHE
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C H A P T E R 8■ ■ ■Making Be
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CHAPTER 8 ■ USING THE COMMAND LIN
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C H A P T E R 9■ ■ ■Working w
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CHAPTER 9 ■ WORKING WITH TEXT IN
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C H A P T E R 10■ ■ ■Things G
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CHAPTER 10 ■ THINGS GO IN, THINGS
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C H A P T E R 11■ ■ ■Tracking
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CHAPTER 11 ■ TRACKING DOWN BUGSTh
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CHAPTER 11 ■ TRACKING DOWN BUGS01
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CHAPTER 11 ■ TRACKING DOWN BUGS
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CHAPTER 11 ■ TRACKING DOWN BUGSTh
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CHAPTER 11 ■ TRACKING DOWN BUGSAn
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CHAPTER 11 ■ TRACKING DOWN BUGS#
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C H A P T E R 12■ ■ ■Managing
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CHAPTER 12 ■ MANAGING TIME AND PE
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APPENDIX■ ■ ■Perl TipsSee rec
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APPENDIX ■ PERL TIPS• Date::Par
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APPENDIX ■ PERL TIPSPerl Syntax N
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■ ■ ■Index■Symbols$CDPATH,
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■ INDEXenscript option (printing)
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■ INDEX■NNagiosadding hosts to,
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■ INDEXsyslogcentralized logging
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