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Usage of undefined variable.
PropertyValue
SeverityWarning
CategoryCorrectness
DefaultEnabled

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Description

This check ensures that environment variables and build arguments are correctly declared before being used. While undeclared variables might not cause an immediate build failure, they can lead to unexpected behavior. It also detects common mistakes like typos in variable names. This check does not evaluate undefined variables for RUN, CMD, and ENTRYPOINT instructions where you use the shell form, because when you use shell form, variables are resolved by the command shell.

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Examples

Bad: 
FROM alpine AS base
COPY $foo .
Good: 
FROM alpine AS base
ARG foo
COPY $foo .
Bad (typo detection): 
FROM alpine
ENV PATH=$PAHT:/app/bin
Output: Usage of undefined variable '$PAHT' (did you mean $PATH?)

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Supersedes

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Reference