The document discusses configuration management and infrastructure as code. It describes how configuration management tools like Chef can be used to automate server configuration and deployment through declarative scripts. This allows infrastructure to be treated as code, making it version controlled, tested, and able to recover from failures through immutable deployments that replace servers rather than modify them.

1. Configuration Management
~ S. Meena
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2. Configuration management
• Creating and maintaining consistency
• Installing, updating, reporting
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What is it?

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We need a new way to work
Infrastructure needs to be
●Repeatable
●Testable
●Scalable
●Flexible:
●Work on web architectures and cloud computing
Why we need it?

4. DevOps?
1. Agile Development Practices applied to
infrastructure
2. New tooling to automate infrastructure
3. Testing, testing, testing
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Who does it?

5. DevOps (continued)
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Development
•Team focus
•IDE/workbench
•Agile methodology
•Source control
Who are they?

6. DevOps (continued)
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Operations
•Individual focus
•Scripts Based
•No methodology
•No Source control

7. Operations as Code
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8. Simple Application
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Source: https://www.digitalocean.com/community/tutorials/5-common-server-
setups-for-your-web-application

9. Separate Database
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Source: https://www.digitalocean.com/community/tutorials/5-common-server-
setups-for-your-web-application

10. Load balancer
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Source: https://www.digitalocean.com/community/tutorials/5-common-server-
setups-for-your-web-application

11. HTTP Accelerator (Caching Reverse
Proxy)
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Source: https://www.digitalocean.com/community/tutorials/5-common-server-
setups-for-your-web-application

12. Master-Slave Database Replication
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Source: https://www.digitalocean.com/community/tutorials/5-common-server-
setups-for-your-web-application

13. Combining the Concepts
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Source: https://www.digitalocean.com/community/tutorials/5-common-server-setups-for-
your-web-application

14. Nodes
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Lb.srv.01
cache.srv.01
cache.srv.02
app.srv.01
app.srv.02
db.srv.01
db.srv.02

15. Nodes ~ Roles
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loadbalancer
memcached
memcached
webserver
webserver
dbMaster
dbSlave

16. Recipes
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Loadbalancer
(HAProxy) Memcached
(memcached)
memcached
Webserver
(Apache)
webserver
dbMaster
(mysql)
dbSlave
• Apache2
• Mysql
• Haproxy
• memcached

17. Infrastructure as code
• Automate the creation and maintenance of
servers (to the farthest extent possible)
– Build from source control
– Utilize open source tools
– Ensure testability
• A practice popularized by the DevOps
movement.
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18. Challenges
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Configuration Synchronization
Server-A Server - B

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Configuration Drift
Server-A Server - B Server - B
Manual Change

21. No Manual Changes
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You can’t
touch this

22. How Servers Should be?
• Immutable Servers: a server that once
deployed, is never modified, merely replaced
with a new updated instance.
• PhoenixServer: A server should be like a
phoenix, regularly rising from the ashes
• SnowflakeServer: server that is difficult to
reproduce.
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23. Immutable servers
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http://martinfowler.com/bliki/ImmutableServer.html

24. Phoenix Server
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• It avoids configuration drift and
hence protecting server from
becoming SnowflakeServer
• use software that automatically
re-syncs servers with a known
baseline

25. Properties of CM Tools
• DECLARATIVE LANGUAGE
• KNOWN STATE
• IDEMPOTENCE
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26. DECLARATIVE LANGUAGE
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Package
File1
File2
Service

27. KNOWN STATE
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File1
packa
ge
service
File2
File1
Server-A Server - B
converge
Code run

28. IDEMPOTENCE
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Server-A Server - B

29. Architecture
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30. Standalone
• Runs locally
• Requires that a cookbook (and any of its
dependencies) be on the same physical disk as
the node
• Eg. Chef-solo, ansible
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31. Client-server
• A client/server architecture.
• The server has a reference configuration.
• The client queries the server.
• The client makes change in order to match
the reference configuration.
• Eg. Chef-server, ansible-tower
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1. REQ: “Can you give my configuration model ?“
2. ACK: “Ok, for you, that's it.”
3. “I make the necessary in order to fulfil it.”
4. (optional) “Thank you, I'm ok, no error” or
“I had a problem”.

33. Benefit of this approach
• Centralized management
• Mass deployment
• Automated management
• Configuration customization
• Abstraction Layer
• Idempotence
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Tools

35. CM Usage Flow
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36. Chef is..
●A library for Configuration Management
●A Configuration Management System
●A Systems Integration Platform
●An API for your entire infrastructure
●Open-source!
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Chef’s Architecture

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Vagrant
$> vagrant box add
$> vagrant init
$> vagrant up
$> vagrant ssh
$> vagrant provision
$> vagrant suspend
$> vagrant destroy

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Dependency management
Tools:
Berkshelf
librarian-chef

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Unit testing
chefspec
(ruby gem)
https://github.com/acrmp/chefspec
Test a cookbook
fast and from
anywhere
spec/default_spec.rb

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Continuous testing
guard
(ruby gem)
https://github.com/guard/guard
When a local file
changes, then
run unit tests.
Guardfile

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Integration Testing
test kitchen
(ruby gem)
https://github.com/opscode/test-kitchen
Run and test
cookbook in
Vagrant or LXC
container.
.kitchen.yml

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Static Analysis
foodcritic
(ruby gem)
http://acrmp.github.io/foodcritic/
Style guide and
find defects in
cookbook source
code.

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Continuous integration
Jenkins
(Java app)
When a change
is checked in,
then run tests
and deploy to
Chef Server.

45. References
• Images:
– https://www.digitalocean.com/community/tutorials/5-common-server-
setups-for-your-web-application
• Slideshare
– Infrastructure as Code (BBWorld/DevCon13) by Mike McGarr
– Automated infrastructure is on the menu by jtimberman
– Configuration manager presentation by jeyg
– Infrastructure as Code - ABUG Session by Patrick Debois
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