配置kubelet在coreos上使用RKT而不是docker

我正在尝试按照https://coreos.com/kubernetes/docs/latest/deploy-master.html中描述的方式部署主节点在CoreOS测试版(1153.4.0)。

我使用以下kubecconfig yaml文件:

 current-context: tuxin-coreos-context
 apiVersion: v1
 clusters:
 - cluster:
     certificate-authority: /etc/kubernetes/ssl/ca.pem
     server: https://coreos-2.tux-in.com:443
   name: tuxin-coreos-cluster
 contexts:
 - context:
     cluster: tuxin-coreos-cluster
   name: tuxin-coreos-context
 kind: Config
 preferences:
   colors: true
 users:
 - name: ufk
   user:
     client-certificate: /etc/kubernetes/ssl/apiserver.pem
     client-key: /etc/kubernetes/ssl/apiserver-key.pem

我使用的是KUBELET_VERSION v1.4.0-beta.10_coreos.0

systemctl cat kubelet返回以下内容:

<标题>/etc/systemd/系统/kubelet.service h1> journalctl -b -u kubelet返回

Sep 26 17:58:53 coreos-2.tux-in.com systemd[1]: Starting kubelet.service...
Sep 26 17:58:53 coreos-2.tux-in.com systemd[1]: Started kubelet.service.
Sep 26 17:58:53 coreos-2.tux-in.com kubelet-wrapper[1725]: image: using image from file /usr/lib64/rkt/stage1-images/stage1-fly.aci
Sep 26 17:58:54 coreos-2.tux-in.com kubelet-wrapper[1725]: image: using image from local store for image name quay.io/coreos/hyperkube:v1.4.0-beta.10_coreos.0
Sep 26 17:59:11 coreos-2.tux-in.com kubelet-wrapper[1725]: W0926 17:59:11.807917    1725 server.go:383] No API client: no api servers specified
Sep 26 17:59:12 coreos-2.tux-in.com kubelet-wrapper[1725]: I0926 17:59:12.871488    1725 manager.go:140] cAdvisor running in container: "/system.slice/kubelet.service"
Sep 26 17:59:14 coreos-2.tux-in.com kubelet-wrapper[1725]: I0926 17:59:14.454499    1725 fs.go:116] Filesystem partitions: map[/dev/sda9:{mountpoint:/var/lib/docker major:8 minor:9 fsType:ext4 blockSize:0} /dev/sda3:{mountpoint:/etc/ssl/certs major:8 minor:3 fsType:ext4 blockSize:0} overlay:{mountpoint:/ major:0 minor:54 fsType:overlay blockSize:0}]
Sep 26 17:59:14 coreos-2.tux-in.com kubelet-wrapper[1725]: I0926 17:59:14.458559    1725 manager.go:195] Machine: {NumCores:8 CpuFrequency:3060000 MemoryCapacity:4145504256 MachineID:f3e41f31b6024d84806ddf3a54075add SystemUUID:00000000-0000-0000-0000-1C6F653E6F72 BootID:ca4acb17-baa6-4863-acdb-2db06609b0d8 Filesystems:[{Device:/dev/sda3 Capacity:1031946240 Type:vfs Inodes:260096 HasInodes:true} {Device:overlay Capacity:984373800960 Type:vfs Inodes:61054976 HasInodes:true} {Device:/dev/sda9 Capacity:113819422720 Type:vfs Inodes:28536576 HasInodes:true}] DiskMap:map[8:0:{Name:sda Major:8 Minor:0 Size:120034123776 Scheduler:cfq} 8:16:{Name:sdb Major:8 Minor:16 Size:1000204886016 Scheduler:cfq} 8:32:{Name:sdc Major:8 Minor:32 Size:3000592982016 Scheduler:cfq} 8:48:{Name:sdd Major:8 Minor:48 Size:2000398934016 Scheduler:cfq} 8:64:{Name:sde Major:8 Minor:64 Size:1000204886016 Scheduler:cfq}] NetworkDevices:[{Name:enp4s0 MacAddress:1c:6f:65:3e:6f:72 Speed:1000 Mtu:1500} {Name:flannel.1 MacAddress:6a:5e:8b:1d:00:17 Speed:0 Mtu:1450}] Topology:[{Id:0 Memory:4145504256 Cores:[{Id:0 Threads:[0 4] Caches:[{Size:32768 Type:Data Level:1} {Size:32768 Type:Instruction Level:1} {Size:262144 Type:Unified Level:2}]} {Id:1 Threads:[1 5] Caches:[{Size:32768 Type:Data Level:1} {Size:32768 Type:Instruction Level:1} {Size:262144 Type:Unified Level:2}]} {Id:2 Threads:[2 6] Caches:[{Size:32768 Type:Data Level:1} {Size:32768 Type:Instruction Level:1} {Size:262144 Type:Unified Level:2}]} {Id:3 Threads:[3 7] Caches:[{Size:32768 Type:Data Level:1} {Size:32768 Type:Instruction Level:1} {Size:262144 Type:Unified Level:2}]}] Caches:[{Size:8388608 Type:Unified Level:3}]}] CloudProvider:Unknown InstanceType:Unknown InstanceID:None}
Sep 26 17:59:14 coreos-2.tux-in.com kubelet-wrapper[1725]: I0926 17:59:14.459359    1725 manager.go:201] Version: {KernelVersion:4.7.1-coreos ContainerOsVersion:CoreOS 1153.4.0 (MoreOS) DockerVersion:1.11.2 CadvisorVersion: CadvisorRevision:}
Sep 26 17:59:14 coreos-2.tux-in.com kubelet-wrapper[1725]: W0926 17:59:14.460736    1725 server.go:613] No api server defined - no events will be sent to API server.
Sep 26 17:59:14 coreos-2.tux-in.com kubelet-wrapper[1725]: I0926 17:59:14.460794    1725 kubelet.go:255] Adding manifest file: /etc/kubernetes/manifests
Sep 26 17:59:14 coreos-2.tux-in.com kubelet-wrapper[1725]: W0926 17:59:14.463983    1725 kubelet_network.go:64] Hairpin mode set to "promiscuous-bridge" but container runtime is "rkt", ignoring
Sep 26 17:59:14 coreos-2.tux-in.com kubelet-wrapper[1725]: I0926 17:59:14.464034    1725 kubelet.go:516] Hairpin mode set to "none"
Sep 26 17:59:14 coreos-2.tux-in.com kubelet-wrapper[1725]: Error: failed to run Kubelet: failed to create kubelet: cannot find rkt binary: exec: "rkt": executable file not found in $PATH
Sep 26 17:59:14 coreos-2.tux-in.com kubelet-wrapper[1725]: failed to run Kubelet: failed to create kubelet: cannot find rkt binary: exec: "rkt": executable file not found in $PATH
Sep 26 17:59:14 coreos-2.tux-in.com systemd[1]: kubelet.service: Main process exited, code=exited, status=1/FAILURE
Sep 26 17:59:14 coreos-2.tux-in.com systemd[1]: kubelet.service: Unit entered failed state.
Sep 26 17:59:14 coreos-2.tux-in.com systemd[1]: kubelet.service: Failed with result 'exit-code'.
Sep 26 17:59:24 coreos-2.tux-in.com systemd[1]: kubelet.service: Service hold-off time over, scheduling restart.
Sep 26 17:59:24 coreos-2.tux-in.com systemd[1]: Stopped kubelet.service.

我试图指定rkt的特定路径，我试图在我的核心操作系统上使用相同的路径，这是/bin/rkt，但它无法在那里找到二进制文件。超立方体图像是否由于某种原因缺少RKT二进制?

<标题> 更新

ok，我试着进一步调试这个问题，但又进入了死胡同。

我尝试手动运行所有内容以查看问题所在。

所以我设置了以下环境变量:

export KUBELET_VERSION=v1.4.0_coreos.0
export RKT_OPTS=--volume var-log,kind=host,source=/var/log 
 --mount volume=var-log,target=/var/log 
 --volume dns,kind=host,source=/etc/resolv.conf 
 --mount volume=dns,target=/etc/resolv.conf

然后我将/usr/lib/coreos/kubelet-wrapper文件复制到我的主目录并修改为运行bash:

...
${KUBELET_ACI}:${KUBELET_VERSION} --exec=/bin/bash

然后我用以下参数运行kubelet:

./kubelet-wrapper   --kubeconfig=/var/lib/kubelet/kubeconfig    --network-plugin-dir=/etc/kubernetes/cni/net.d     --network-plugin=cni     --register-schedulable=false     --allow-privileged=true    --pod-manifest-path=/etc/kubernetes/manifests     --hostname-override=coreos-2.tux-in.com     --container-runtime=rkt

然后在得到bash提示之后，我用以下参数运行kubelet:

./kubelet --kubeconfig=/var/lib/kubelet/kubeconfig  
  --network-plugin-dir=/etc/kubernetes/cni/net.d   
  --network-plugin=cni   
  --register-schedulable=false   
  --allow-privileged=true  
  --pod-manifest-path=/etc/kubernetes/manifests   
  --hostname-override=coreos-2.tux-in.com   
  --container-runtime=rkt

，我又得到了cannot find rkt binary错误信息。我试图通过运行find / | grep rkt$在该容器中找到rkt二进制文件，但没有找到rkt二进制文件。

设置将rkt作为运行时的kubernetes的最简单方法是使用这里找到的脚本。正如Rob所说，看到这个错误的原因是kubelet在容器中运行，没有看到主机上的/usr/bin/rkt。

现在，让容器化的kubelet正确地与主机上的rkt运行时通信有点复杂。仅仅将rkt二进制文件绑定到kubelet容器中是不够的。详细信息在此PR中捕获。

我们花了一些努力使这一切在coreos-kubernetes仓库中顺利工作，并测试了结果。如果您使用该存储库中的脚本，则只需将CONTAINER_RUNTIME环境变量设置为rkt即可。

现在手工过程有点棘手，但是coreos-kubernetes中的自动脚本，如kube-aws工具或Vagrant文档可以很好地完成这项工作。

在您的特定环境中，rkt二进制文件需要从主机使用RKT_OPTS挂载到包装器中(这意味着它会自动更新)，然后您需要向API服务器添加更多标志:

--container-runtime=rkt

--rkt-api-endpoint=HOST:PORT

--rkt-path=PATH_TO_RKT_BINARY

--rkt-stage1-image=STAGE1

随着rkt + kubernetes的调试过程和最佳实践变得更加清晰，CoreOS打算随着时间的推移发布更好的手动说明。

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