pub fn dockerfile_from_ref(dockerfile: &str) -> Option<&str>Expand description
The image ref in a Dockerfile’s first FROM, or None when it has none.
Deliberately loose on whitespace and case, and it ignores --platform= and AS name
decoration, because the check exists to catch a base that disagrees rather than to
validate Dockerfile syntax.
Split-and-scan rather than a regex: the pattern is “first token after FROM on a line
whose first word is FROM”, which split_whitespace states more directly than a
pattern string would. (regex-lite is available if this ever grows.)