cassandra-checks: Unify entrypoint copy and format

It's copied at the end of the Dockerfile so modification to it do not rebuild
deps. The entrypoint script is also adapted to work with actual docker run
calls.

apps/cassandra-checks/Dockerfile

@@ -14,15 +14,16 @@ USER swh
 WORKDIR /opt/swh
 
 COPY --chown=swh:swh requirements-frozen.txt /opt/swh
-COPY --chown=swh:swh entrypoint.sh /opt/swh
 
 ENV PYTHONPATH=/opt/swh
 ENV PATH=/opt/swh/.local/bin:$PATH
 
-RUN chmod u+x /opt/swh/entrypoint.sh && \
-    /usr/local/bin/python -m pip install --upgrade pip && \
+RUN /usr/local/bin/python -m pip install --upgrade pip && \
     pip install --no-cache-dir -r requirements-frozen.txt
 
+COPY --chown=swh:swh entrypoint.sh /opt/swh
+RUN chmod u+x /opt/swh/entrypoint.sh
+
 ENV SWH_CONFIG_FILENAME=/etc/swh/config.yml
 
 ENTRYPOINT ["/opt/swh/entrypoint.sh"]

apps/cassandra-checks/entrypoint.sh

@@ -14,13 +14,16 @@ else
 fi
 
 case "$1" in
-  "shell")
-    shift
-    echo "Running command $@"
-    exec bash -i "$@"
-    ;;
-  *)
-    echo Starting Cassandra objects checker.
-    exec $CLONE_DIR/sysadmin/cassandra_checks/get_journal_check_and_replay.py
-    ;;
+    "shell")
+        shift
+        if (( $# == 0)); then
+            exec bash -i
+        else
+            "$@"
+        fi
+        ;;
+    *)
+        echo Starting Cassandra objects checker.
+        exec $CLONE_DIR/sysadmin/cassandra_checks/get_journal_check_and_replay.py
+        ;;
 esac