What you will learn
- Define idempotency
- Make scripts safe to re-run
- Use guards and checks
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The basics, in plain English
A safe automation can run twice without causing damage. “Idempotent” is the fancy word for: running it again gives the same result, instead of creating duplicates or breaking things. This is a core habit in DevOps.
- Idempotent
- Safe to run repeatedly. The 2nd, 3rd, 100th run changes nothing extra.
- Why it matters
- Automation often re-runs after failures; you do not want duplicates or surprises.
- Check then act
- The habit of first checking if something already exists before creating it.
- Desired state
- Describing what you want the end result to be, and letting the tool reach it.
- Side effect
- Any change a command makes to the world, like writing a file or sending an email.
01
Run it twice
An idempotent script produces the same result whether run once or ten times. Check before you create; this is the heart of configuration management.
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