Repeatable deployment: ARM templates vs Bicep vs imperative scripts
Verdict: Declare the desired end state in ARM template JSON for repeatable, dependency-ordered deployments. Author Bicep when the JSON is too verbose; it compiles to the same templates. Imperative CLI or PowerShell scripts force you to sequence resources by hand.
| Criterion | ARM templates | Bicep | Imperative scripts |
|---|---|---|---|
| Style | Declarative JSON, desired end state | Declarative, concise language | Imperative, step-by-step commands |
| Dependency ordering | Azure orchestrates in correct order | Same as ARM, compiles to it | Author sequences resources manually |
| Repeatability | Same result across dev, test, prod | Same result across dev, test, prod | Drifts between runs and environments |
| Choose when | Repeatable, interdependent resource stacks | You find raw ARM JSON verbose | Ad-hoc one-off actions |
Rules
- Choose ARM templates to define resources declaratively in JSON; Azure validates the template then orchestrates creation in dependency order across dev, test and production.
- ARM templates build interdependent resources in the correct order automatically, so you never hand-code the sequence.
- Choose Bicep when raw ARM JSON is too verbose; it is a more concise declarative language that compiles down to the same ARM templates.
Traps
- Imperative PowerShell or CLI scripts create resources one at a time, so the author must encode ordering by hand instead of declaring end state.