changed entry point setup

Dockerfile.linux

@@ -30,10 +30,10 @@ run apt-get update && \
 # Make binary name configurable
 arg BINARY_NAME
 env BINARY_NAME=${BINARY_NAME:-WatcherAgent}
-copy --from=linux-builder /app/target/x86_64-unknown-linux-gnu/release/$BINARY_NAME /usr/local/bin/
+copy --from=linux-builder /app/target/x86_64-unknown-linux-gnu/release/${BINARY_NAME} /usr/local/bin/
 
 # Health check
 healthcheck --interval=30s --timeout=3s \
-  cmd /usr/local/bin/$BINARY_NAME healthcheck || exit 1
+  cmd /usr/local/bin/${BINARY_NAME} healthcheck || exit 1
 
 ENTRYPOINT ["/bin/sh", "-c", "/usr/local/bin/${BINARY_NAME}"]