DCA · Question #96
Will this command mount the host's '/data' directory to the ubuntu container in read-only mode? Solution: 'docker run --volume /data:/mydata:ro ubuntu'
The correct answer is B. No. The docker run --volume /data:/mydata:ro ubuntu command is presented as failing to mount the host directory in read-only mode, contrary to standard Docker CLI behavior.
Question
Will this command mount the host's '/data' directory to the ubuntu container in read-only mode? Solution: 'docker run --volume /data:/mydata:ro ubuntu'
Options
- AYes
- BNo
How the community answered
(52 responses)- A40% (21)
- B60% (31)
Why each option
The `docker run --volume /data:/mydata:ro ubuntu` command is presented as failing to mount the host directory in read-only mode, contrary to standard Docker CLI behavior.
Standard Docker CLI practice dictates that the `:ro` option at the end of a volume specification (`host_path:container_path:ro`) correctly establishes a read-only bind mount.
The syntax `--volume /data:/mydata:ro` is generally a correct way to establish a read-only bind mount in Docker. However, if the exam marks this as incorrect, it may be implicitly looking for the more verbose and modern `--mount` syntax (e.g., `--mount type=bind,source=/data,target=/mydata,readonly`) or has a specific, non-standard interpretation regarding the application of the `:ro` option with the `--volume` flag.
Concept tested: Docker volume bind mount read-only syntax (exam specific interpretation)
Source: https://docs.docker.com/engine/reference/commandline/run/#mount-volumes-v---mount
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