Slides defining DevOps and typical its operation flow.

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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