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Dockerfile: Remove VOLUME instruction #20

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Jan 8, 2019
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Dockerfile: Remove VOLUME instruction #20

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4 changes: 2 additions & 2 deletions Dockerfile
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Original file line number Diff line number Diff line change
Expand Up @@ -19,10 +19,10 @@ COPY --from=builder ${FROM_DIRECTORY}/consoles/ /usr

RUN ln -s /usr/share/prometheus/console_libraries /usr/share/prometheus/consoles/ /etc/prometheus/
RUN mkdir -p /prometheus && \
chown -R nobody:nobody etc/prometheus /prometheus
chgrp -R 0 /etc/prometheus /prometheus && \
chmod -R g=u /etc/prometheus /prometheus

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What's the reason for changing the ownership here? I'm not sure who is the default owner of the /prometheus directory, but wouldn't this change cause prometheus to no longer be able to write to the /prometheus dir?

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These two commands are recommended by official OKD docs to be set on directories you'd need to write in runtime. https://docs.okd.io/3.10/creating_images/guidelines.html#use-uid

Probably since VOLUME was used before permissions where working OK but these commands explicitly will set root group and allows it to write to this directory, even if user ID is randomly set.

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Ok, makes sense.

USER nobody
EXPOSE 9090
VOLUME [ "/prometheus" ]
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I'd like to keep the configuration in sync with upstream prometheus as much as possible, so I'll probably wait for prometheus#5050 to be merged first.

In general it seems that this case is a bit different than kubernetes/kube-state-metrics#471, since the /prometheus directory contains data that should normally be persisted between container restarts.

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@aramalipoor aramalipoor Jan 8, 2019 •
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What this change will help is to avoid creating temporary volumes (i.e. within /var/lib/docker) while the user deliberately does not want to persist data and also helps with deploying this image on cloud providers who have restricted using VOLUME instruction / temporary volumes on host disk.

WORKDIR /etc/prometheus
ENTRYPOINT [ "/bin/prometheus" ]
4 changes: 2 additions & 2 deletions Dockerfile.rhel
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Original file line number Diff line number Diff line change
Expand Up @@ -19,11 +19,11 @@ COPY --from=builder ${FROM_DIRECTORY}/consoles/ /usr

RUN ln -s /usr/share/prometheus/console_libraries /usr/share/prometheus/consoles/ /etc/prometheus/
RUN mkdir -p /prometheus && \
chown -R nobody:nobody etc/prometheus /prometheus
chgrp -R 0 /etc/prometheus /prometheus && \
chmod -R g=u /etc/prometheus /prometheus

USER nobody
EXPOSE 9090
VOLUME [ "/prometheus" ]
WORKDIR /prometheus
ENTRYPOINT [ "/bin/prometheus" ]
CMD [ "--config.file=/etc/prometheus/prometheus.yml", \
Expand Down
4 changes: 2 additions & 2 deletions Dockerfile.rhel7
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Expand Up @@ -10,11 +10,11 @@ RUN yum install -y prometheus && \
yum clean all
RUN ln -s /usr/share/prometheus/console_libraries /usr/share/prometheus/consoles/ /etc/prometheus/
RUN mkdir -p /prometheus && \
chown -R nobody:nobody etc/prometheus /prometheus
chgrp -R 0 /etc/prometheus /prometheus && \
chmod -R g=u /etc/prometheus /prometheus

USER nobody
EXPOSE 9090
VOLUME [ "/prometheus" ]
WORKDIR /prometheus
ENTRYPOINT [ "/bin/prometheus" ]
CMD [ "--config.file=/etc/prometheus/prometheus.yml", \
Expand Down