[nginx] docker build failing for nginx/nginx-prometheus-exporter

[shauke]

Actual Behavior

Running docker build -t nginx nginx currently results in an error for the nginx/nginx-prometheus-exporter step.

 > [stage-2 4/6] COPY --from=nginx/nginx-prometheus-exporter /usr/bin/exporter /nginx-prometheus-exporter:
------
failed to compute cache key: "/usr/bin/exporter" not found: not found

Investigation Notes
The problem occurs with the latest version (0.9.0) of https://hub.docker.com/r/nginx/nginx-prometheus-exporter/tags?page=1&ordering=last_updated that was just recently released.

With a pined version nginx/nginx-prometheus-exporter:0.8.0 this problem does not occur.

Quick Fix
Change the according line in nginx/Dockerfile from

COPY --from=nginx/nginx-prometheus-exporter /usr/bin/exporter /nginx-prometheus-exporter

to

COPY --from=nginx/nginx-prometheus-exporter:0.8.0 /usr/bin/exporter /nginx-prometheus-exporter

Environment Details

• Docker version 20.10.5, build 55c4c88

[jometzner]

Using latest as tag of base image can result in such failures.

[shauke]

Reason for Build Failure
The entrypoint for the nginx/nginx-prometheus-exporter was changed from ENTRYPOINT [ "/usr/bin/exporter" ] to ENTRYPOINT [ "/usr/bin/nginx-prometheus-exporter" ] so our /nginx/Dockerfile needs to be adapted as well to build again.
https://github.com/nginxinc/nginx-prometheus-exporter/pull/164/files#diff-5aecd73bbcb9b7410938673269f0d4e676dd18509277b0ff2f2787c9d3e22604R17

0.8.0

0.9.0