46 lines
1.6 KiB
Markdown
46 lines
1.6 KiB
Markdown
# Imperative vs declarative
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Configuration management tools are usually classified as either **imperative** or **declarative**.
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Imperative means that you define the steps which are necessary to achieve the goal.
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Declarative means that you just define the state you want to achieve, and the tooling makes it happen.
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### Declarative
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**Pros**
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* Easier configuration as you just define the desired end-state
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and you don't need to check nor remember the actual state.
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**Cons**
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* No or only little control over the execution order resp. control flow
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* Race conditions can lead to bugs which can be difficult to reproduce resp. solve
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* Difficult to debug
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* The built-in checks for the actual state and the required steps usually don't cover all edge case.
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Declarative provisioning may not be able to meet complexer requirements and/or may result in errors.
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### Imperative
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**Pros**
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* Gives control over the execution order resp. control flow
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* Easier to debug step-by-step execution
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**Cons**
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* More complicated and more work as you need to define the required steps yourself and may need to check the current state.
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### Implarative
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We prefer systems which are offering best of both worlds, i.e. advantages from the **imperative** paradigm as:
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* control of execution order (with all kinds of looping and conditional possibilities)
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* easy debugging
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* being able to cover complex cases
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as well as important advantages of the **declarative** paradigm, such as:
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* easy configuration
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* idempotence resp. quasi-idempotence
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* no need to check nor remember the system state.
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We call this "implarative".
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