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useradd without flag -l and high UID will result in excessively large image.
PropertyValue
SeverityWarning
CategoryPerformance
DefaultEnabled
Auto-fixYes (--fix)

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Description

Without the -l or --no-log-init flag, useradd will add the user to the lastlog and faillog databases. This can result in the creation of logically large (sparse) files under /var/log, which inflates container image sizes due to the lack of support for sparse files in overlay filesystems.

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Examples

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Problematic code

RUN useradd -u 123456 foobar

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Correct code

RUN useradd -l -u 123456 foobar

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Auto-fix

Inserts -l flag after useradd when UID is greater than 99999 and -l/--no-log-init is not already present. 
# Before
RUN useradd -u 100001 appuser

# After (with --fix)
RUN useradd -u 100001 -l appuser

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Reference