mirror of
https://github.com/containers/youki
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220 lines
9.8 KiB
Markdown
220 lines
9.8 KiB
Markdown
# youki: A container runtime in Rust
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[](https://discord.gg/zHnyXKSQFD)
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[](https://github.com/containers/youki/graphs/commit-activity)
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[](https://github.com/containers/youki/graphs/contributors)
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[](https://github.com/containers/youki/actions)
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[](https://codecov.io/gh/containers/youki)
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<p align="center">
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<img src="docs/youki.png" width="230" height="230">
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</p>
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youki is an implementation of [runtime-spec](https://github.com/opencontainers/runtime-spec) in Rust, referring to [runc](https://github.com/opencontainers/runc).
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# About the name
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youki is pronounced as /joʊki/ or yoh-key.
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youki is named after a Japanese word 'youki', which means 'a container'. In Japanese language, youki also means 'cheerful', 'merry', or 'hilarious'.
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# Motivation
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Here is why I am rewriting a new container runtime in Rust.
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- Rust is one of the best languages to implement oci-runtime. Many container tools are written in Go. It's all very nice products. However, the container runtime requires the use of system calls, which requires a bit of special handling when implemented in Go. This is too tricky(e.g. _namespaces(7)_, _fork(2)_); with Rust, it's not that tricky and you can use system calls. Also, unlike C, Rust provides the benefit of memory management. Rust is not yet a major player in the container field, and Rust has the potential to contribute more to this field. I hope to be one of the examples of how Rust can be used in this field.
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- youki has the potential to be faster and use less memory than runc. This means that it can work in environments with tight memory usage. I don't have any benchmarks, etc., as it is not yet fully operational, but I expect that it will probably perform better when implemented in Rust. In fact, [crun](https://github.com/containers/crun#performance), a container runtime implemented in C, is quite high performance. For example, it may be possible to experiment with asynchronous processing using async/await in some parts.
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- The development of [railcar](https://github.com/oracle/railcar) has been suspended. This project was very nice but is no longer being developed. This project is inspired by it.
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- I have fun implementing this. In fact, this may be the most important.
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# Related project
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- [containers/oci-spec-rs](https://github.com/containers/oci-spec-rs) - OCI Runtime and Image Spec in Rust
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# Status of youki
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youki is not at the practical stage yet. However, it is getting closer to practical use, running with docker and passing all the default tests provided by [opencontainers/runtime-tools](https://github.com/opencontainers/runtime-tools).
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| Feature | Description | State |
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| :------------: | :---------------------------------------------: | :-------------------------------------------------------------------------------------------------: |
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| Docker | Running via Docker | ✅ |
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| Podman | Running via Podman | It works, but cgroups isn't supported. WIP on [#24](https://github.com/containers/youki/issues/24) |
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| pivot_root | Change the root directory | ✅ |
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| Mounts | Mount files and directories to container | ✅ |
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| Namespaces | Isolation of various resources | ✅ |
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| Capabilities | Limiting root privileges | ✅ |
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| Cgroups v1 | Resource limitations, etc | ✅ |
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| Cgroups v2 | Improved version of v1 | Support is complete except for devices. WIP on [#78](https://github.com/containers/youki/issues/78) |
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| Seccomp | Filtering system calls | WIP on [#25](https://github.com/containers/youki/issues/25) |
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| Hooks | Add custom processing during container creation | ✅ |
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| Rootless | Running a container without root privileges | It works, but cgroups isn't supported. WIP on [#77](https://github.com/containers/youki/issues/77) |
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| OCI Compliance | Compliance with OCI Runtime Spec | 45 out of 55 test cases passing |
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# Design and implementation of youki
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More details are in the works [#14](https://github.com/containers/youki/issues/14)
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# Getting Started
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Local build is only supported on linux.
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For other platforms, please use [Vagrantfile](#setting-up-vagrant) that we prepared.
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## Requires
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- Rust(See [here](https://www.rust-lang.org/tools/install))
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- Docker(See [here](https://docs.docker.com/engine/install))
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## Dependencies
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### Debian, Ubuntu and related distributions
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```sh
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$ sudo apt-get install \
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pkg-config \
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libsystemd-dev \
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libdbus-glib-1-dev \
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build-essential \
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libelf-dev
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```
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### Fedora, Centos, RHEL and related distributions
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```sh
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$ sudo dnf install \
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pkg-config \
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systemd-devel \
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dbus-devel \
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elfutils-libelf-devel \
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```
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## Build
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```sh
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$ git clone git@github.com:containers/youki.git
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$ cd youki
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$ ./build.sh
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$ ./youki -h # you can get information about youki command
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```
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## Tutorial
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Let's try to run a container that executes `sleep 30` with youki. This tutorial may need root permission.
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```sh
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$ git clone git@github.com:containers/youki.git
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$ cd youki
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$ ./build.sh
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$ mkdir -p tutorial/rootfs
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$ cd tutorial
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# use docker to export busybox into the rootfs directory
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$ docker export $(docker create busybox) | tar -C rootfs -xvf -
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```
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Then, we need to prepare a configuration file. This file contains metadata and specs for a container, such as the process to run, environment variables to inject, sandboxing features to use, etc.
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```sh
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$ ../youki spec # will generate a spec file named config.json
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```
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We can edit the `config.json` to add customized behaviors for container. Here, we modify the `process` field to run `sleep 30`.
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```json
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"process": {
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...
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"args": [
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"sleep", "30"
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],
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...
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}
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```
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Then we can explore the lifecycle of a container:
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```sh
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$ sudo ./youki create -b tutorial tutorial_container # create a container with name `tutorial_container`
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$ sudo ./youki state tutorial_container # you can see the state the container is `created`
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$ sudo ./youki start tutorial_container # start the container
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$ sudo ./youki list # will show the list of containers, the container is `running`
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$ sudo ./youki delete tutorial_container # delete the container
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```
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Change the command to be executed in `config.json` and try something other than `sleep 30`.
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## Usage
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Starting the docker daemon.
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```
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$ dockerd --experimental --add-runtime="youki=$(pwd)/target/x86_64-unknown-linux-gnu/debug/youki"
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```
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In case you get an error like :
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```
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failed to start daemon: pid file found, ensure docker is not running or delete /var/run/docker.pid
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```
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That means your normal Docker daemon is running, and it needs to be stopped. For that, open a new shell in same directory and run :
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```
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$ systemctl stop docker # might need root permission
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```
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Now in the same shell run the first command, which should start the docker daemon.
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You can use youki in a different terminal to start the container.
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```
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$ docker run -it --rm --runtime youki busybox
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```
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Afterwards, you can close the docker daemon process in other the other terminal. To restart normal docker daemon (if you had stopped it before), run :
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```
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$ systemctl start docker # might need root permission
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```
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### Integration test
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Go and node-tap are required to run integration test. See the [opencontainers/runtime-tools](https://github.com/opencontainers/runtime-tools) README for details.
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```
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$ git submodule update --init --recursive
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$ ./integration_test.sh
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# run specific test_cases with pattern
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$ ./integration_test.sh linux_*
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```
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### Setting up Vagrant
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You can try youki on platforms other than linux by using the Vagrantfile we have prepared.
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```
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$ git clone git@github.com:containers/youki.git
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$ cd youki
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$ vagrant up
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$ vagrant ssh
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# in virtual machine
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$ cd youki
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$ ./build.sh
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```
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# Community
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We also have an active [Discord](https://discord.gg/h7R3HgWUct) if you'd like to come and chat with us.
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# Contribution
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This project welcomes your PR and issues.
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For example, refactoring, adding features, correcting English, etc.
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If you need any help, you can contact me on [Twitter](https://twitter.com/utam0k).
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Thanks to all the people who already contributed!
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<a href="https://github.com/containers/youki/graphs/contributors">
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<img src="https://contributors-img.web.app/image?repo=containers/youki" />
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</a>
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