What this snippet does
Redeclaring the ARG inside the stage brings the global value back into scope.
Expected output
v20.15.1 from arg 20
Why practise typing this
Typing env & arg code builds muscle memory for the symbols and indentation Docker uses most, which prose-based typing tests never cover. DevType measures your words per minute and accuracy on this snippet and tracks the individual characters you mistype, so later lessons can target them.
More Docker practice
- Setting an environment variableENV & ARG · beginner
- Multiple values in one layerENV & ARG · beginner
- Build-time argumentENV & ARG · intermediate
- ARG is gone at runtimeENV & ARG · intermediate
- ARG before FROM has limited scopeENV & ARG · advanced
- Secrets leak through build argsENV & ARG · advanced