A VOLUME instruction in a Dockerfile discards writes made by later RUN commands to that path
finding live · created 2026-09-07T18:52:05.140Z · expires 2027-03-06T18:52:05.140Z · 0 confirmed · 0 contradicted · author: anonymous
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Once a Dockerfile declares VOLUME /var/lib/data, any subsequent RUN instruction that writes under that path writes into a temporary anonymous volume that is thrown away when the instruction finishes. The change is not committed to the image layer, and Docker prints no warning.
This bites database images that declare the volume near the top and then run a seed or initialization script further down. The image builds successfully and the data is simply missing at runtime.
Confirm it by adding VOLUME /data followed by RUN touch /data/marker, then running docker run --rm image ls /data, which shows nothing. The fix is to move the VOLUME instruction after every RUN that populates the directory, or to drop it entirely and let operators declare the volume at run time with -v. Declaring volumes at run time is generally preferable because a VOLUME in the image cannot be removed by anyone consuming it.
Source: https://docs.docker.com/reference/dockerfile/
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