runtime-rs is a new component introduced in Kata Containers 3.0, it is a Rust version of runtime(shim). It like runtime, but they have many difference:
runtime-rsis written in Rust, andruntimeis written in Go.runtimeis the default shim in Kata Containers 3.0,runtime-rsis still under heavy development.runtime-rshas a completed different architecture thanruntime, you can check at the architecture overview.
Note:
runtime-rs is still under heavy development, you should avoid using it in critical system.
Also, runtime-rs provides the following features:
- Turn key solution with builtin
DragonballSandbox, all components in one process - Async I/O to reduce resource consumption
- Extensible framework for multiple services, runtimes and hypervisors
- Lifecycle management for sandbox and container associated resources
See the architecture overview
for details on the runtime-rs design.
runtime-rs is a runtime written in Rust, it is composed of several crates.
This picture shows the overview about the crates under this directory and the relation between crates.
Not all the features have been implemented yet, for details please check the roadmap.
The runtime-rs directory contains some crates in the crates directory that compose the containerd-shim-kata-v2.
| Crate | Description |
|---|---|
shim |
containerd shimv2 implementation |
service |
services for containers, includes task service |
runtimes |
container runtimes |
resource |
sandbox and container resources |
hypervisor |
hypervisor that act as a sandbox |
agent |
library used to communicate with agent in the guest OS |
persist |
persist container state to disk |
shim is the entry point of the containerd shim process, it implements containerd shim's binary protocol:
- start: start a new shim process
- delete: delete exist a shim process
- run: run ttRPC service in shim
containerd will launch a shim process and the shim process will serve as a ttRPC server to provide shim service through TaskService from service crate.
The runtime-rs has an extensible framework, includes extension of services, runtimes, and hypervisors.
Currently, only containerd compatible TaskService is implemented.
TaskService has implemented the containerd shim protocol,
and interacts with runtimes through messages.
Runtime is a container runtime, the runtime handler handles messages from task services to manage containers. Runtime handler and Runtime instance is used to deal with the operation for sandbox and container.
Currently, only VirtContainer has been implemented.
In runtime-rs, all networks/volumes/rootfs are abstracted as resources.
Resources are classified into two types:
- sandbox resources: network, share-fs
- container resources: rootfs, volume, cgroup
Here is a detailed description of the resources.
For VirtContainer, there will be more hypervisors to choose.
Currently, built-in Dragonball has been implemented. We have also added initial support for cloud-hypervisor with CI being added next.
agent is used to communicate with agent in the guest OS from the shim side. The only supported agent is KataAgent.
Persist defines traits and functions to help different components save state to disk and load state from disk.
Some helper libraries are maintained in the library directory so that they can be shared with other rust components.
See the build from the source section of the rust runtime installation guide.
runtime-rs has the same configuration as runtime with some limitations.
See the debugging section of the developer guide.
See the debugging section of the developer guide.
An experimental alternative binary is available that removes containerd dependencies and makes it easier to run the shim proper outside of the runtime's usual deployment environment (i.e. on a developer machine).
For Kata Containers limitations, see the limitations file for further details.
runtime-rs is under heavy developments, and doesn't support all features as the Golang version runtime, check the roadmap for details.