# hcsshim

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This package contains the Golang interface for using the Windows [Host Compute Service](https://techcommunity.microsoft.com/t5/containers/introducing-the-host-compute-service-hcs/ba-p/382332) (HCS) to launch and manage [Windows Containers](https://docs.microsoft.com/en-us/virtualization/windowscontainers/about/). It also contains other helpers and functions for managing Windows Containers such as the Golang interface for the Host Network Service (HNS), as well as code for the [guest agent](./internal/guest/README.md) (commonly referred to as the GCS or Guest Compute Service in the codebase) used to support running Linux Hyper-V containers.

It is primarily used in the [Moby](https://github.com/moby/moby) and [Containerd](https://github.com/containerd/containerd) projects, but it can be freely used by other projects as well.

## Building

While this repository can be used as a library of sorts to call the HCS apis, there are a couple binaries built out of the repository as well. The main ones being the Linux guest agent, and an implementation of the [runtime v2 containerd shim api](https://github.com/containerd/containerd/blob/master/runtime/v2/README.md).
### Linux Hyper-V Container Guest Agent

To build the Linux guest agent itself all that's needed is to set your GOOS to "Linux" and build out of ./cmd/gcs.
```powershell
C:\> $env:GOOS="linux"
C:\> go build .\cmd\gcs\
```

or on a Linux machine
```sh
> go build ./cmd/gcs
```

If you want it to be packaged inside of a rootfs to boot with alongside all of the other tools then you'll need to provide a rootfs that it can be packaged inside of. An easy way is to export the rootfs of a container.

```sh
docker pull busybox
docker run --name base_image_container busybox
docker export base_image_container | gzip > base.tar.gz
BASE=./base.tar.gz
make all
```

If the build is successful, in the `./out` folder you should see:
```sh
> ls ./out/
delta.tar.gz  initrd.img  rootfs.tar.gz
```

### Containerd Shim
For info on the Runtime V2 API: https://github.com/containerd/containerd/blob/master/runtime/v2/README.md.

Contrary to the typical Linux architecture of shim -> runc, the runhcs shim is used both to launch and manage the lifetime of containers.

```powershell
C:\> $env:GOOS="windows"
C:\> go build .\cmd\containerd-shim-runhcs-v1
```

Then place the binary in the same directory that Containerd is located at in your environment. A default Containerd configuration file can be generated by running:
```powershell
.\containerd.exe config default | Out-File "C:\Program Files\containerd\config.toml" -Encoding ascii
```

This config file will already have the shim set as the default runtime for cri interactions.

To trial using the shim out with ctr.exe:
```powershell
C:\> ctr.exe run --runtime io.containerd.runhcs.v1 --rm mcr.microsoft.com/windows/nanoserver:2004 windows-test cmd /c "echo Hello World!"
```

## Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a
Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us
the rights to use your contribution. For details, visit https://cla.microsoft.com.

When you submit a pull request, a CLA-bot will automatically determine whether you need to provide
a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions
provided by the bot. You will only need to do this once across all repos using our CLA.

We also require that contributors [sign their commits](https://git-scm.com/docs/git-commit) using `git commit -s` or `git commit --signoff` to
certify they either authored the work themselves or otherwise have permission to use it in this project. Please see https://developercertificate.org/ for
more info, as well as to make sure that you can attest to the rules listed. Our CI uses the [DCO Github app](https://github.com/apps/dco) to ensure
that all commits in a given PR are signed-off.

## Code of Conduct

This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/).
For more information see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or
contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additional questions or comments.

## Dependencies

This project requires Golang 1.17 or newer to build.

For system requirements to run this project, see the Microsoft docs on [Windows Container requirements](https://docs.microsoft.com/en-us/virtualization/windowscontainers/deploy-containers/system-requirements).

## Reporting Security Issues

Security issues and bugs should be reported privately, via email, to the Microsoft Security
Response Center (MSRC) at [secure@microsoft.com](mailto:secure@microsoft.com). You should
receive a response within 24 hours. If for some reason you do not, please follow up via
email to ensure we received your original message. Further information, including the
[MSRC PGP](https://technet.microsoft.com/en-us/security/dn606155) key, can be found in
the [Security TechCenter](https://technet.microsoft.com/en-us/security/default).

For additional details, see [Report a Computer Security Vulnerability](https://technet.microsoft.com/en-us/security/ff852094.aspx) on Technet

---------------
Copyright (c) 2018 Microsoft Corp.  All rights reserved.
