WHY ?
弥补了传统容器技术安全性的缺点，Kata Containers通过使用硬件虚拟化来达到容器隔离的目的。每一个container/pod 都是基于一个独立的kernel实例来作为一个轻量级的虚拟机。自从每一个container/pod运行与独立的虚拟机上，他们不再从宿主机内核上获取相应所有的权限。
WHAT ?
kata containers是由OpenStack基金会管理的容器项目。kata containers整合了Intel的 Clear Containers 和 Hyper.sh 的 runV，能够支持不同平台的硬件，并符合Open Container Initiative规范，同时还可以兼容k8s的 CRI（Container Runtime Interface）接口规范。项目包含几个配套组件，即Runtime，Agent， Proxy，Shim等。项目已于6月份release了1.0版本。
从docker架构上看，kata-container和原来的runc是平级的。大家知道docker只是管理容器生命周期的框架，真正启动容器最早用的是LXC，然后是runc，现在也可以换成kata了。所以说kata-container可以当做docker的一个插件，启动kata-container可以通过docker命令。
kata container组件
1. Agent
Kata-agent运行在guest负责管理容器。Kata-agent的执行单元是定义了一系列命名空间的沙盒。每个VM可以运行多个容器，支持k8s一个pod运行多个容器的需求。不过目前docker中，kata-runtime只能一个pod一个容器。Kata-agent通过gRPC和其他kata组件通信。Kata-agent使用libcontainer管理容器的生命周期
2. Runtime
kata-runtime是一个OCI兼容的容器运行时，负责处理OCI运行时规范指定的所有命令并启动kata-shim实例
配置文件是/usr/share/defaults/kata-containers/configuration.toml
# XXX: WARNING: this file is auto-generated.
# XXX:
# XXX: Source file: "cli/config/configuration.toml.in"
# XXX: Project:
# XXX: Name: Kata Containers
# XXX: Type: kata
[hypervisor.qemu]
path = "/usr/bin/qemu-lite-system-x86_64"
kernel = "/usr/share/kata-containers/vmlinuz.container"
image = "/usr/share/kata-containers/kata-containers.img"
machine_type = "pc"
# Optional space-separated list of options to pass to the guest kernel.
# For example, use `kernel_params = "vsyscall=emulate"` if you are having
# trouble running pre-2.15 glibc.
#
# WARNING: - any parameter specified here will take priority over the default
# parameter value of the same name used to start the virtual machine.
# Do not set values here unless you understand the impact of doing so as you
# may stop the virtual machine from booting.
# To see the list of default parameters, enable hypervisor debug, create a
# container and look for 'default-kernel-parameters' log entries.
kernel_params = ""
# Path to the firmware.
# If you want that qemu uses the default firmware leave this option empty
firmware = ""3. Proxy
默认使用virtio-serial和VM通信。VM可以运行多个容器进程。在使用virtio-serial的情况下，与每个进程相关联的I/O流需要在主机上多路复用和解复用。
Kata-proxy给多个kata-shim和kata-runtime客户端提供对kata-agent提供访问，它的主要作用是在每个kata-shim和kata-agent之间路由I/O流和信号。Kata-proxy连接到kata-agent的unix域套接字上，这个套接字是kata-proxy启动时kata-runtime提供的
4. Shim
runtime运行在宿主机上，不能直接监控运行在虚拟机里的进程，最多只能看到QEMU进程。kata-shim监控容器进程，处理容器的所有I/O流，包括stdout、stdin和stderr，以及转发所有的要发送出去的信号。
Kata-shim还有其他功能：
- 通过一个UNIX域套接字连接到kata-proxy。这个套接字在kata-runtime启动kata-shim的时候，由kata-runtime传给kata-shim，同时带上了containerID和execID，两个ID用来识别shim管理的是哪个容器。
- 读取VM内部容器进程的输出流和错误流
- 使用SignalProcessRequest API转发从reaper到kata-proxy的信号
- 监控终端修改，并使用grpc TtyWinResize API转发到kata-proxy
kata-runtime kata-env
[Meta]
Version = "1.0.18"[Runtime]
Debug = false
Path = "/usr/bin/kata-runtime"
[Runtime.Version]
Semver = "1.3.1"
Commit = "258eae0"
OCI = "1.0.1"
[Runtime.Config]
Path = "/etc/kata-containers/configuration.toml"[Hypervisor]
MachineType = "pc"
Version = "QEMU emulator version 2.11.0\nCopyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers"
Path = "/usr/bin/qemu-lite-system-x86_64"
BlockDeviceDriver = "virtio-scsi"
EntropySource = "/dev/urandom"
Msize9p = 8192
MemorySlots = 10
Debug = false
UseVSock = false[Image]
Path = "/usr/share/kata-containers/kata-containers-image_clearlinux_1.3.1_agent_c7fdd324cda.img"[Kernel]
Path = "/usr/share/kata-containers/vmlinuz-4.14.67.16-4.4.container"
Parameters = ""[Initrd]
Path = ""[Proxy]
Type = "kataProxy"
Version = "kata-proxy version 1.3.1-d364b2e"
Path = "/usr/libexec/kata-containers/kata-proxy"
Debug = false[Shim]
Type = "kataShim"
Version = "kata-shim version 1.3.1-58f757d"
Path = "/usr/libexec/kata-containers/kata-shim"
Debug = false[Agent]
Type = "kata"[Host]
Kernel = "3.10.0-957.el7.x86_64"
Architecture = "amd64"
VMContainerCapable = true
SupportVSocks = false
[Host.Distro]
Name = "CentOS Linux"
Version = "7"
[Host.CPU]
Vendor = "GenuineIntel"
Model = "Intel(R) Core(TM) i7-6500U CPU @ 2.50GHz"[Netmon]
Version = "kata-netmon version 1.3.1"
Path = "/usr/libexec/kata-containers/kata-netmon"
Debug = false
Enable = false
HOW ?
1. centos 7 安装docker
yum -y install yum-utilsyum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo yum -y install docker-ce
2. centos 7 安装kata-containers
source /etc/os-releaseecho $VERSION_ID VERSION_ID=$VERSION_ID yum-config-manager --add-repo \ "http://download.opensuse.org/repositories/home:/katacontainers:/release/CentOS_${VERSION_ID}/home:katacontainers:release.repo" yum -y install kata-runtime kata-proxy kata-shim
3. 配置docker启动runtime参数
--add-runtime kata-runtime=/usr/bin/kata-runtime --default-runtime=kata-runtime
[Unit]
Description=Docker Application Container Engine
Documentation=http://docs.docker.com
After=network.target docker-storage-setup.service
Wants=docker-storage-setup.service
[Service]
Type=notify
Environment=GOTRACEBACK=crash
ExecReload=/bin/kill -s HUP $MAINPID
Delegate=yes
KillMode=process
ExecStart=/usr/bin/dockerd -s overlay2 --storage-opt overlay2.override_kernel_check=1 \
--add-runtime kata-runtime=/usr/bin/kata-runtime --default-runtime=kata-runtime \
$DOCKER_OPTS \
$DOCKER_STORAGE_OPTIONS \
$DOCKER_NETWORK_OPTIONS \
$DOCKER_DNS_OPTIONS \
$INSECURE_REGISTRY
LimitNOFILE=1048576
LimitNPROC=1048576
LimitCORE=infinity
TimeoutStartSec=1min
Restart=on-abnormal
[Install]
WantedBy=multi-user.target
4. 重启docker进程
systemctl daemon-reload && systemctl restart docker
启动容器，查看容器状态，docker stats，同时发现启动qemu进程
katacontainer kubernetes 集成安装
a. 使用 rpm 安装
http://download.opensuse.org/repositories/home:/katacontainers:/releases:/x86_64:/master/CentOS_7/x86_64/ http://download.opensuse.org/repositories/home:/katacontainers:/releases:/x86_64:/stable-1.3/CentOS_7/x86_64/4 安装
b. runc
不用 docker 跟 k8s 通信而是用 cri-o，同时支持普通容器和 kata 容器，要单独安装 runc
https://github.com/opencontainers/runc/releases/download/v1.0.0-rc8/runc.amd64
chmod +x runc.amd64
mv runc.amd64 /usr/bin/runc
c. 安装 crictl CLI
d. crio
https://kubernetes.io/docs/setup/production-environment/container-runtimes/#cri-o
Prerequisites
modprobe overlay
modprobe br_netfilter# Setup required sysctl params, these persist across reboots.
cat > /etc/sysctl.d/99-kubernetes-cri.conf <<EOF
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOFsysctl --system
# Install prerequisites
yum-config-manager --add-repo=https://cbs.centos.org/repos/paas7-crio-311-candidate/x86_64/os/# Install CRI-O
yum install --nogpgcheck cri-o/etc/crio/crio.conf 可以使用命令 "crio config --default >/etc/crio/crio.conf" 创建，然后修改 registries 即可：
e. 配置 crio
修改 kata-runtime
# runtime_untrusted_workload is the OCI compatible runtime used for untrusted
# container workloads. This is an optional setting, except if
# default_container_trust is set to "untrusted".
runtime_untrusted_workload = "/usr/bin/kata-runtime"修改镜像仓库
registries = [
"docker.io"
]修改 cgroupfs 等
# cgroup_manager is the cgroup management implementation to be used
# for the runtime.
cgroup_manager = "cgroupfs"修改 pause 地址
# pause_image is the image which we use to instantiate infra containers.
pause_image = "zhangzhonglin/pause-amd64:3.0"修改 plugin_dir 路径
# plugin_dir is is where CNI plugin binaries are stored.
plugin_dir = "/opt/k8s/bin"Start CRI-O systemctl start crio
f. kubelet 配置
添加参数 --container-runtime=remote --runtime-request-timeout=15m --container-runtime-endpoint=unix:///var/run/crio/crio.sock
测试启动一个 deployment 以注解 io.kubernetes.cri-o.TrustedSandbox: "false"：
spec:
replicas: 1
selector:
matchLabels:
app: wordpress-hostpath
tier: mysql-hostpath
strategy:
type: Recreate
template:
metadata:
annotations:
io.kubernetes.cri-o.TrustedSandbox: "false"crictl image
# crictl images
IMAGE TAG IMAGE ID SIZE
docker.io/calico/cni v3.7.4 203668d151b2e 139MB
docker.io/calico/kube-controllers v3.7.4 e67ede28cc7e4 46.8MB
docker.io/calico/node v3.7.4 84b65b552a8f0 159MB
docker.io/coredns/coredns 1.5.0 7987f0908caf3 42.7MB
docker.io/zhangzhonglin/pause-amd64 3.0 99e59f495ffaa 753kB发现启动 crio common 进程
启动 qemu 进程
总结：
这个镜像管理比较搓，下载到本地还是不可以，必须是 crio.cfg 配置中的仓库必须能通才可以，containerd 最起码可以管理镜像可以 load
安装 kata-runtime，先验证环境是否支持虚拟化环境，否则就白玩了
kata-runtime kata-env，中 VMContainerCapable = true 这个是支持虚拟化环境。
2. 使用 containerd 作为 CRI
下载地址：https://github.com/containerd/containerd/releases
解压至目录 /usr/bin 下
sudo systemctl start containerd
sudo systemctl status containerd
containerd config default 生成默认配置，位置/etc/containerd/config.toml2.1 crictl配置
# cat /etc/crictl.yaml
runtime-endpoint: unix:///run/containerd/containerd.sock
image-endpoint: unix:///run/containerd/containerd.sock
timeout: 10
debug: true2.2 containerd配置
containerd config default > /etc/containerd/config.toml
# cat /etc/containerd/config.toml
root = "/var/lib/containerd"
state = "/run/containerd"
oom_score = 0[grpc]
address = "/run/containerd/containerd.sock"
uid = 0
gid = 0.........................................................................
2.2.1 kata-container cri 插件配置，对于 1.5+版本
plugins.cri.containerd.runtimes.runc: the runc, and it is the default runtime
plugins.cri.containerd.runtimes.kata: The function in containerd (reference the document here) where the dot-connected string io.containerd.kata.v2 is translated to containerd-shim-kata-v2
[plugins.cri.containerd] no_pivot = false
[plugins.cri.containerd.runtimes]
[plugins.cri.containerd.runtimes.runc]
runtime_type = "io.containerd.runc.v1"
[plugins.cri.containerd.runtimes.runc.options]
NoPivotRoot = false
NoNewKeyring = false
ShimCgroup = ""
IoUid = 0
IoGid = 0
BinaryName = "runc"
Root = ""
CriuPath = ""
SystemdCgroup = false
[plugins.cri.containerd.runtimes.kata]
runtime_type = "io.containerd.kata.v2"
[plugins.cri.containerd.runtimes.katacli]
runtime_type = "io.containerd.runc.v1"
[plugins.cri.containerd.runtimes.katacli.options]
NoPivotRoot = false
NoNewKeyring = false
ShimCgroup = ""
IoUid = 0
IoGid = 0
BinaryName = "/usr/bin/kata-runtime"
Root = ""
CriuPath = ""
SystemdCgroup = false参考： https://github.com/kata-containers/documentation/blob/master/how-to/containerd-kata.md
2.3 kubelet配置添加如下：
--runtime-cgroups=/system.slice/containerd.service --container-runtime=remote --runtime-request-timeout=15m --container-runtime-endpoint=unix:///run/containerd/containerd.sock镜像下载的问题
ctr cri load xxx.tar
参考：
katacontainer 原理架构
Overview
kata-container 和 runc是平级的。docker 管理容器生命周期的框架，而真正启动容器是 runc，可以换成 kata。kata-container可以当做 docker 的一个插件
参考：
https://github.com/kata-containers/documentation/blob/master/design/architecture.md
