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Merge pull request #618 from amshinde/update-virtiofs-docs

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Foward-port :virtiofs: Update virtiofs docs
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Peng Tao 2020-08-31 17:29:28 +08:00 committed by GitHub
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docs/how-to/how-to-use-virtio-fs-with-kata.md
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@ -13,7 +13,7 @@ As of the 1.7 release of Kata Containers, [9pfs](https://www.kernel.org/doc/Docu
To help address these limitations, [virtio-fs](https://virtio-fs.gitlab.io/) has been developed. virtio-fs is a shared file system that lets virtual machines access a directory tree on the host. In Kata Containers, virtio-fs can be used to share container volumes, secrets, config-maps, configuration files (hostname, hosts, `resolv.conf`) and the container rootfs on the host with the guest. virtio-fs provides significant performance and POSIX compliance improvements compared to 9pfs.
Enabling of virtio-fs requires changes in the guest kernel as well as the VMM. For Kata Containers, experimental virtio-fs support is enabled through the [NEMU VMM](https://github.com/intel/nemu).
Enabling of virtio-fs requires changes in the guest kernel as well as the VMM. For Kata Containers, experimental virtio-fs support is enabled through `qemu` and `cloud-hypervisor` VMMs.
**Note: virtio-fs support is experimental in the 1.7 release of Kata Containers. Work is underway to improve stability, performance and upstream integration. This is available for early preview - use at your own risk**
@ -21,31 +21,41 @@ This document describes how to get Kata Containers to work with virtio-fs.
## Pre-requisites
* Before Kata 1.8 this feature required the host to have hugepages support enabled. Enable this with the `sysctl vm.nr_hugepages=1024` command on the host.
Before Kata 1.8 this feature required the host to have hugepages support enabled. Enable this with the `sysctl vm.nr_hugepages=1024` command on the host.In later versions of Kata, virtio-fs leverages `/dev/shm` as the shared memory backend. The default size of `/dev/shm` on a system is typically half of the total system memory. This can pose a physical limit to the maximum number of pods that can be launched with virtio-fs. This can be overcome by increasing the size of `/dev/shm` as shown below:
```bash
$ mount -o remount,size=${desired_shm_size} /dev/shm
```
## Install Kata Containers with virtio-fs support
The Kata Containers NEMU configuration, the NEMU VMM and the `virtiofs` daemon are available in the [Kata Container release](https://github.com/kata-containers/kata-containers/releases) artifacts starting with the 1.7 release. While the feature is experimental, distribution packages are not supported, but installation is available through [`kata-deploy`](../../tools/packaging/kata-deploy).
The Kata Containers `qemu` configuration with virtio-fs and the `virtiofs` daemon are available in the [Kata Container release](https://github.com/kata-containers/runtime/releases) artifacts starting with the 1.9 release. Installation is available through [distribution packages](https://github.com/kata-containers/documentation/blob/master/install/README.md#supported-distributions) as well through [`kata-deploy`](https://github.com/kata-containers/packaging/tree/master/kata-deploy).
Install the latest release of Kata as follows:
**Note: Support for virtio-fs was first introduced in `NEMU` hypervisor in Kata 1.8 release. This hypervisor has been deprecated.**
Install the latest release of Kata with `kata-deploy` as follows:
```
docker run --runtime=runc -v /opt/kata:/opt/kata -v /var/run/dbus:/var/run/dbus -v /run/systemd:/run/systemd -v /etc/docker:/etc/docker -it katadocker/kata-deploy kata-deploy-docker install
```
This will place the Kata release artifacts in `/opt/kata`, and update Docker's configuration to include a runtime target, `kata-nemu`. Learn more about `kata-deploy` and how to use `kata-deploy` in Kubernetes [here](../../tools/packaging/kata-deploy/README.md#kubernetes-quick-start).
This will place the Kata release artifacts in `/opt/kata`, and update Docker's configuration to include a runtime target, `kata-qemu-virtiofs`. Learn more about `kata-deploy` and how to use `kata-deploy` in Kubernetes [here](https://github.com/kata-containers/packaging/tree/master/kata-deploy#kubernetes-quick-start).
## Run a Kata Container utilizing virtio-fs
Once installed, start a new container, utilizing NEMU + `virtiofs`:
Once installed, start a new container, utilizing `qemu` + `virtiofs`:
```bash
$ docker run --runtime=kata-nemu -it busybox
$ docker run --runtime=kata-qemu-virtiofs -it busybox
```
Verify the new container is running with the NEMU hypervisor as well as using `virtiofsd`. To do this look for the hypervisor path and the `virtiofs` daemon process on the host:
Verify the new container is running with the `qemu` hypervisor as well as using `virtiofsd`. To do this look for the hypervisor path and the `virtiofs` daemon process on the host:
```bash
$ ps -aux | grep virtiofs
root ... /home/foo/build-x86_64_virt/x86_64_virt-softmmu/qemu-system-x86_64_virt
... -machine virt,accel=kvm,kernel_irqchip,nvdimm ...
root ... /home/foo/build-x86_64_virt/virtiofsd-x86_64 ...
```
You can also try out virtio-fs using `cloud-hypervisor` VMM:
```bash
$ docker run --runtime=kata-clh -it busybox
```