正解:B
In the given Dockerfile, the WORKDIR /app command sets the working directory for any subsequent commands to /app. This means that any commands following this line will be executed within the /app directory inside the Docker container. The COPY . . command copies the contents of the current directory on the host machine to the /app directory in the container. Finally, the CMD ["node", "source/server.js"] command specifies the command to run when the container starts, which in this case is node source/server.js.
Reference:
Dockerfile Reference - WORKDIR