hadolint/DL3044¶

Do not refer to an undefined variable.

Superseded by buildkit/UndefinedVar, which provides the same check with typo detection.

Description¶

Ensures that environment variables and build arguments are declared before being used. Undeclared variables can lead to unexpected behavior or build errors.

Examples¶

Problematic code¶

FROM alpine
COPY $foo .

Correct code¶

FROM alpine
ARG foo
COPY $foo .

Reference¶

• hadolint/DL3044