Configuration Management Tools

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SCM Software Configuration Management

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Captain Obvious alert!

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This is why... Let’s talk about the basics

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what are Software Configurations ?

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The system behavior Hardware configurations System configurations Applications settings Organization policies

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Configurations ≈ Policies The port 80 must be open The user X must have access MySQL database must be running Ping must be blocked

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what does Software Configurations look like?

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Configurations

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Configurations

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Configurations

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Configurations

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Configurations

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Configurations

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Configurations

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Configurations

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what is a SCM system?

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SCM Systems Provisioning Change management

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SCM on Modern Systems

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From 1 machine to many

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Working on the wrong server

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From 1 sysadmin to many

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Who did what?

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What do we need? All changes documented All changes must be repeatable All changes in one place Accesibles for anyone All changes must be traceable

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What does traceable mean? What have been changed? When have been changed? Who made the change?

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What do we do? Configuration by hand Wiki One or few scripts Better scripts + Wiki Better scripts + Git/Svn Custom SCM (script+git+ssh loop)

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How is a modern SCM? Declarative Abstract Idempotent Convergent

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How is a modern SCM? Declarative Abstract Idempotent Convergent What NOT How

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How is a modern SCM? Declarative Abstract Idempotent Convergent How it should behave Rely on the tool for the implementation

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How is a modern SCM? Declarative Abstract Idempotent Convergent Only take action if it’s needed

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How is a modern SCM? Declarative Abstract Idempotent Convergent Each resource takes care of itself

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Key concepts Modern SCM

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Modern SCM’s concepts Resources Nodes/Minions Recipes/Manifests/Playbooks Inventory Roles/Profiles

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Some extras do we have time?

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Avoid manual processes They are error prone

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No content

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But be careful ;-)

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Make Apps SCM friendly Separate data from code Allow to use ENV variables Set default options But allow overwrite them with conffiles

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Do NOT hardcode settings!!! Ever!

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Make Apps SCM friendly Use the dependency managers Composer Bundler Pip npm Maven

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Make Apps SCM friendly Use flags to activate features Use standard formats Think about settings per environment

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Recomendations Start small Think in policies not in manual changes Use Vagrant for developing policies