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Docker Announces Version 1.2.0 and DockerCon Europe


Docker has announced the release of version 1.2.0, including the ability to specify restart policies for containers or fine grain controls over containers permissions. The company is also hosting the first official european conference, DockerCon Europe, in December in Amsterdam.

New features

Restart policies

Docker 1.2.0 new restart policy feature allows containers to restart on exit, to recover from possible container failures.

A new --restart flag was added to docker run to specify one of the three policies available:

  • no: Do not restart the container if it dies, the default behavior.
  • on-failure: Restart the container if it exits with a non-zero exit code, with an optional maximum restart count (e.g. on-failure:5).
  • always: Always restart the container no matter what exit code is returned. This deprecates the --restart flag on the Docker daemon.

For example, to make Redis endlessly try to restart if the container exits:

docker run --restart=always redis

Fine grained container capabilities

Using --privileged was not recommended for use in production in previous versions, as it would allow containers to access host resources. With this release --cap-add and --cap-drop can be used with docker run to control the capabilities granted to a particular container.

For example, to change the status of the container’s interfaces:

docker run --cap-add=NET_ADMIN ubuntu sh -c "ip link eth0 down"

To prevent any chown in the container:

docker run --cap-drop=CHOWN ...

Mounting devices in unprivileged containers

Mounting devices no longer require a privileged container. This release introduces the --device flag in docker run which lets the container use a specific device without requiring --privileged.

For example, to use the sound card inside the container:

docker run --device=/dev/snd:/dev/snd ...

Writable hosts, hostname, resolve.conf

The /etc/hosts, /etc/hostname and /etc/resolve.conf can now be edited in a running container, allowing the execution of services like bind that might write to them. The changes to these files are however only applied at run time, and are not preserved when building a container image.

DockerCon Europe 2014

After last June DockerCon in San Francisco, the first official conference organized in Europe will take place in Amsterdam, at the NEMO science center, December 4th and 5th. Speakers include Ben Golub, CEO, and Solomon Hykes, Founder and CTO of Docker Inc. The day prior to the conference it will take place an "Introduction to Docker" training led by Jérôme Petazzoni , a course introducing the Docker platform, going through installation, integration, and execution.

Docker has also announced a partnership with VMware focused on ensuring that Docker runs on VMware virtual solutions, creating interoperable management tooling, and collaborating on the Docker community’s core technology standards, in particular libcontainer and libswarm orchestration interoperability technologies.

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