容器停止时由容器创建的Docker卷会发生什么

Question

This is my Dockerfile for an spring boot app

FROM openjdk:8u151-jdk-alpine
VOLUME /tmp
ADD target/classes/application.properties /workdir/application.properties
ADD target/foo-app-2.0.0.jar /workdir/app.jar
WORKDIR /workdir
ENV JAVA_OPTS=""
EXPOSE 8080
ENTRYPOINT [ "sh", "-c", "java $JAVA_OPTS -Djava.security.egd=file:/dev/./urandom -jar app.jar" ]

It creates a volume /tmp when the container is started which is stored in /var/lib/docker folder of the host.

Is that volume deleted when the container is stopped ie everything from the host machine for that volume is cleaned up? If not how do I configure that?

Answer 1

No, volumes are not deleted automatically (even if the container gets deleted) and you can list them using the docker volume ls command.

This could cause the presence of a possibly high number of dangling volumes (volumes not associated to any container) in the host. To remove them you can use this command for example:

docker volume rm `docker volume ls -q -f dangling=true`

(Took from here https://coderwall.com/p/hdsfpq/docker-remove-all-dangling-volumes )

Answer 2

Adding to @Whites11 answer -

No, volumes are not deleted automatically/by_default (even if the container gets deleted) and you can list them using docker volume ls command.

However, once your containers are stopped you can remove the volumes associated with them by using rm -v :

$ docker stop $CONTAINER_ID && docker rm -v $CONTAINER_ID

Manual -

Usage: docker rm [OPTIONS] CONTAINER [CONTAINER...]

Remove one or more containers

Options:

-f, --force Force the removal of a running container (uses SIGKILL)

-l, --link Remove the specified link
-v, --volumes Remove the volumes associated with the container