Included default flags into Dockerfile entrypoint (#4796)

* included default flags into Dockerfile entrypoint

Signed-off-by: Junyu Wang <junyuw@berkeley.edu>

* keeping style consistent

Co-Authored-By: DrakeW <junyuw@berkeley.edu>
Signed-off-by: Junyu Wang <junyuw@berkeley.edu>

* move prometheus.yml config into entrypoint & point to console template/libraries in etc/prometheus

Signed-off-by: Junyu Wang <junyuw@berkeley.edu>

Dockerfile

@@ -15,8 +15,8 @@ USER       nobody
 EXPOSE     9090
 VOLUME     [ "/prometheus" ]
 WORKDIR    /prometheus
-ENTRYPOINT [ "/bin/prometheus" ]
-CMD        [ "--config.file=/etc/prometheus/prometheus.yml", \
+ENTRYPOINT [ "/bin/prometheus", \
              "--storage.tsdb.path=/prometheus", \
-             "--web.console.libraries=/usr/share/prometheus/console_libraries", \
-             "--web.console.templates=/usr/share/prometheus/consoles" ]
+             "--web.console.libraries=/etc/prometheus/console_libraries", \
+             "--web.console.templates=/etc/prometheus/consoles", \
+             "--config.file=/etc/prometheus/prometheus.yml" ]