发布于 2015-09-10 16:09:28 | 150 次阅读 | 评论: 0 | 来源: 网络整理
v0.3.0 新版功能: Data volumes have been available since version 1 of the Docker Remote API
A data volume is a specially-designated directory within one or more containers that bypasses the Union File System to provide several useful features for persistent or shared data:
Each container can have zero or more data volumes.
Using data volumes is as simple as adding a -v parameter to the docker run command. The -v parameter can be used more than once in order to create more volumes within the new container. To create a new container with two new volumes:
$ docker run -v /var/volume1 -v /var/volume2 busybox true
This command will create the new container with two new volumes that exits instantly (true is pretty much the smallest, simplest program that you can run). Once created you can mount its volumes in any other container using the -volumes-from option; irrespecive of whether the container is running or not.
Or, you can use the VOLUME instruction in a Dockerfile to add one or more new volumes to any container created from that image:
# BUILD-USING: docker build -t data . # RUN-USING: docker run -name DATA data FROM busybox VOLUME ["/var/volume1", "/var/volume2"] CMD ["/usr/bin/true"]
If you have some persistent data that you want to share between containers, or want to use from non-persistent containers, its best to create a named Data Volume Container, and then to mount the data from it.
Create a named container with volumes to share (/var/volume1 and /var/volume2):
$ docker run -v /var/volume1 -v /var/volume2 -name DATA busybox true
Then mount those data volumes into your application containers:
$ docker run -t -i -rm -volumes-from DATA -name client1 ubuntu bash
You can use multiple -volumes-from parameters to bring together multiple data volumes from multiple containers.
Interestingly, you can mount the volumes that came from the DATA container in yet another container via the client1 middleman container:
$ docker run -t -i -rm -volumes-from client1 -name client2 ubuntu bash
This allows you to abstract the actual data source from users of that data, similar to ambassador_pattern_linking.
If you remove containers that mount volumes, including the initial DATA container, or the middleman, the volumes will not be deleted until there are no containers still referencing those volumes. This allows you to upgrade, or effectivly migrate data volumes between containers.
-v=[]: Create a bind mount with: [host-dir]:[container-dir]:[rw|ro].
If host-dir is missing from the command, then docker creates a new volume. If host-dir is present but points to a non-existent directory on the host, Docker will automatically create this directory and use it as the source of the bind-mount.
Note that this is not available from a Dockerfile due the portability and sharing purpose of it. The host-dir volumes are entirely host-dependent and might not work on any other machine.
For example:
sudo docker run -v /var/logs:/var/host_logs:ro ubuntu bash
The command above mounts the host directory /var/logs into the container with read only permissions as /var/host_logs.
v0.5.0 新版功能.