Rocket v1.3.0 发布了。Rocket （也叫 rkt）是 CoreOS 推出的一款容器引擎，和 Docker 类似，帮助开发者打包应用和依赖包到可移植容器中，简化搭环境等部署工作。Rocket 和 Docker 不同的地方在于，Rocket 没有 Docker 那些为企业用户提供的“友好功能”，比如云服务加速工具、集群系统等。反过来说，Rocket 想做的，是一个更纯粹的业界标准。
CoreOS 把它的容器称为 App Containers，里面包含 app container image、runtime、container-discovery 协议等。其中，App Container Image 和 Docker 里的 Image 比较类似，包含应用必需的元素组成，如源代码和二进制文件。Rocket runtime 则是依照 App Container 标准规格打造的，旨在将容器真正的变成一款命令行工具。
改进说明：
New features and UX changes
Propagate exit status from apps inside the pod to rkt (#2308). Previously, if an app exited with a non-zero exit status, rkt's exit status would still be 0. Now, if an app fails, its exit status will be propagated to the outside. While this was partially implemented in some stage1 flavors since rkt v1.1.0, it now works in the default coreos flavor.
Check signatures for stage1 images by default, especially useful when stage1 images are downloaded from the Internet (#2336). This doesn't affect the following cases:
The stage1 image is already in the store
The stage1 image is in the default directory configured at build time
The stage1 image is the default one and it is in the same directory as the rkt binary
Allow downloading of insecure public keys with the
pubkeyinsecure option (#2278).Implement Docker volume semantics (#2315). Docker volumes are initialized with the files in the image if they exist, unless a host directory is mounted there. Implement that behavior in rkt when it runs a Docker converted image.
API service
Return the cgroup when getting information about running pods and add a new cgroup filter (#2331).
Bug fixes
Avoid configuring more CPUs than the host has in the kvm flavor (#2321).
Fix a bug where the proxy configuration wasn't forwarded to docker2aci (docker2aci#147).