Puppet: Eclipsecon ALM 2013

Less talk, more rock

Puppet
ALM Connect 2013

deepak
giridharagopal
deepak@puppetlabs.com
@grim_radical [github twitter freenode]

Classes should be immutable unless
there's a very good reason to make

-- Joshua Bloch, “Effective Java”
them mutable....If a class cannot be
made immutable, limit its mutability
as much as possible.

Immutability allows
for invariants, which
help you reason about
correctness

Immutability prevents
spooky action at a
distance

Immutability fosters
modular, composable
abstractions

(this shouldn’t be
a tough sell to
developers)

That’s great for
develoment, but how
about operations?

Immutability for
infrastructure?
Because operations is in the
same boat as development

Everyone who’s got
their app running on
a fleet of servers has
experienced spooky
action at a distance

Known, good state is
critical for reliable
upgrades

A lack of predictability
in your systems
ruins automation and
abstraction

The problem is that:

Systems are inherently
mutable!

But ideally:

Systems should behave as
though they weren’t!

façade of immutability. Immutability

Computer systems are in many ways
open systems, providing the keys to
the vault if one is so inclined to grab
them. But in order to foster an air of
immutability in our own systems,
it's of utmost importance to create a
façade of immutability. Immutability

-- The Joy of Clojure
requires that we layer over and
abstract the parts of our system that
provide unrestrained mutability.

Describe how you’d
like your systems to
look, and Puppet
does all the hard
work for you!

Example: Inquire
a simple service for
exposing system
metrics

Example: Inquire
http://box/inquire/disk_usage

install apache
create apache user
create apache config file
cgi script for “df -h”
correct perms for script
start apache
restart if config changes!

Once you’ve got a
spec for your service,
you can see if a given
machine is up to code

• Packages: • Data files:
• apache • /var/www/cgi-bin/
• Users: disk_usage
• apache • executable, owned
by apache
• Config files:
• apache’s httpd.conf • does “df -h”
• Services:
• apache should be
running
• restart if config file
changes

class inquire_server {
package { apache: ensure => installed }
user { apache: uid => 1000, shell => "/bin/false" }
service { apache: ensure => running }

file {
"/etc/httpd/httpd.conf":
owner => root,
mode => 644,
source => "puppet://master-server/httpd.conf",
notify => Service[apache];

"/var/www/cgi-bin/disk_usage.sh":
owner => apache,
mode => 755,
content => "/usr/bin/df -h";
}
}

class inquire_bootstrap {

file {
owner => root,
mode => 644,
}
}

class inquire_disk_usage {
include inquire_bootstrap
file {
"/var/www/cgi-bin/disk_usage.sh":
owner => apache,
mode => 755,
content => "/usr/bin/df -h";
}
}

class inquire_bootstrap {

file {
owner => root,
mode => 644,
}
}

define inquiry($command) {
include inquire_bootstrap
file {
"/var/www/cgi-bin/$name.sh":
owner => apache,
mode => 755,
content => $command;
}
}

node “appserver.mydomain.com” {
inquiry {
"disk-usage": command => "df -h";
"processes": command => "ps aux";
"kernel-info": command => "uname -a";
}
}

node “appserver1.mydomain.com” {
inquiry {
}
}

inquiry {
}
}

class instrumentation {
inquiry {
}
}

include instrumentation
}

include instrumentation
}

Rich set of primitives,
and make your own.
Can use existing
modules and
abstractions, and
make your own.

netmask_lo: 255.0.0.0 ipaddress: 172.16.245.128
augeasversion: 0.10.0 processor0: Intel(R) Core(TM)
fqdn: pe-debian6.localdomain i7-2635QM CPU @ 2.00GHz
manufacturer: "VMware, Inc." lsbdistrelease: 6.0.2
processorcount: "1" uniqueid: 007f0101
productname: VMware Virtual hardwaremodel: i686
Platform kernelversion: 2.6.32
physicalprocessorcount: 1 operatingsystem: Debian
facterversion: 1.6.7 architecture: i386
boardproductname: 440BX Desktop lsbdistdescription: Debian GNU/
Reference Platform Linux 6.0.2 (squeeze)
kernelmajversion: "2.6" lsbmajdistrelease: "6"
hardwareisa: unknown interfaces: "eth0,lo"
timezone: PDT ipaddress_lo: 127.0.0.1
puppetversion: 2.7.12 (Puppet uptime_days: 0
Enterprise 2.5.1) lsbdistid: Debian
lsbdistcodename: squeeze rubysitedir: /opt/puppet/lib/
is_virtual: "true" site_ruby/1.8
operatingsystemrelease: 6.0.2 rubyversion: 1.8.7
virtual: vmware osfamily: Debian
type: Other memorytotal: &id001 502.57 MB
domain: localdomain memorysize: *id001
hostname: pe-debian6 boardmanufacturer: Intel
selinux: "false" Corporation
kernel: Linux path: /usr/local/sbin:/usr/

file { “/etc/issue”:
content => “Got an issue? Here’s a tissue!”,
}

file { “/etc/motd”:
content => template(“Welcome to $hostname!”),
}

file { "/etc/sudoers":
owner => root,
group => root,
mode => 440,
source => "puppet:///modules/sudo/sudoers"
}

class ntp {
package { 'ntp':
ensure => installed,
}

service { 'ntpd':
ensure => running,
enable => true,
subscribe => File['/etc/ntp.conf'],
}

file { '/etc/ntp.conf':
ensure => file,
require => Package['ntp'],
source => "puppet:///modules/ntp/ntp.conf",
}
}

node “webserver.mydomain.com” {
include ntp
}

node “appserver.mydomain.com” {
include ntp
}

node “database.mydomain.com” {
include ntp
}

class ssh {

@@sshkey { $hostname:
type => dsa,
key => $sshdsakey
}

Sshkey <<| |>>

}

File “/tmp/foo/bar”
User “deepak”
Dir “/tmp/foo”
Dir “/tmp”

Dir “/tmp” User “deepak”

Dir “/tmp/foo”

File “/tmp/foo/bar”

package { 'ntp':
ensure => installed,
}

service { 'ntpd':
ensure => running,
enable => true,
subscribe => File['/etc/ntp.conf'],
}

file { '/etc/ntp.conf':
ensure => file,
require => Package['ntp'],
source => "puppet:///modules/ntp/ntp.conf",
}

Idempotent, and
only does what’s
necessary

Compensates for the
inherent mutability
of systems

Combats spooky
action at a distance
with automatic
repair

Brings predictability
to your systems

A foundation of
predictability and
reliability lets you
perform higher-level
operations on your
infrastructure

Software-defined
infrastructure is...just
software.
Infrastructure as
code is...just code.

Thus, you can treat it
like the other code in
your application

Maintaining the
state of your systems
is the foundation
upon which
everything rests

Start small, and start
somewhere. :)

deepak
giridharagopal
deepak@puppetlabs.com
@grim_radical [github twitter freenode]

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Puppet: Eclipsecon ALM 2013

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Puppet: Eclipsecon ALM 2013