Quiz: images and data

Question 1 of 10

Why an edit did not reach the container, which build steps docker takes from the cache and what a tag means; where a container's process writes, what survives re-creation and why host directory files will not open. The questions follow the lessons “Dockerfile: your own image” and “Volumes: data outlives the container”.

10 questions · threshold 70%

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The `RUN` line in the Dockerfile did not change. Why did docker run it again?

$ sudo docker build -t site:3 .
#6 [2/4] WORKDIR /www
#6 CACHED
#7 [3/4] COPY index.html .
#7 DONE 0.1s
#8 [4/4] RUN date -u '+%F %T' > built.txt
#8 DONE 0.4s

The cache went stale, since a lot of time has passed since the last build.
docker runs RUN steps on every build.
The COPY step above produced a new layer, and everything below it is built again.
The Dockerfile itself changed.

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Quiz: images and data

The RUN line in the Dockerfile did not change. Why did docker run it again?

The `RUN` line in the Dockerfile did not change. Why did docker run it again?