Kubernetes: エラー解決法 requires conntrack to be installed in root’s path

Ubuntu上に Kubernetes v1.18.0のminikubeをインストールしminikube startコマンドを実行したとろ、下記のエラーが発生し、minikube startコマンドが中断。

エラーメッセージ

$ sudo minikube --driver=none start
😄  minikube v1.9.2 on Ubuntu 16.04 (vbox/amd64)
✨  Using the none driver based on user configuration
💣  Sorry, Kubernetes v1.18.0 requires conntrack to be installed in root's path

解決法

conntrackがインストールされていない為発生したエラー。下記コマンドでconntrackをインストールする。

$ sudo apt install conntrack
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  conntrack
0 upgraded, 1 newly installed, 0 to remove and 1 not upgraded.
Need to get 27.3 kB of archives.
After this operation, 91.1 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu xenial/main amd64 conntrack amd64 1:1.4.3-3 [27.3 kB]
Fetched 27.3 kB in 1s (25.4 kB/s)
Selecting previously unselected package conntrack.
(Reading database ... 62970 files and directories currently installed.)
Preparing to unpack .../conntrack_1%3a1.4.3-3_amd64.deb ...
Unpacking conntrack (1:1.4.3-3) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up conntrack (1:1.4.3-3) ...
$

インストール後は正常にminikubeコマンドを実行できる。

$ sudo minikube start
😄  minikube v1.9.2 on Ubuntu 16.04 (vbox/amd64)
✨  Automatically selected the docker driver
🛑  The "docker" driver should not be used with root privileges.
💡  If you are running minikube within a VM, consider using --driver=none:
📘    https://minikube.sigs.k8s.io/docs/reference/drivers/none/
vagrant@minikube:~$ sudo minikube --driver=none start
😄  minikube v1.9.2 on Ubuntu 16.04 (vbox/amd64)
✨  Using the none driver based on user configuration
👍  Starting control plane node  in cluster minikube
🤹  Running on localhost (CPUs=2, Memory=1999MB, Disk=9861MB) ...
ℹ️  OS release is Ubuntu 16.04.6 LTS
🐳  Preparing Kubernetes v1.18.0 on Docker 18.06.2-ce ...
❗  This bare metal machine is having trouble accessing https://k8s.gcr.io
💡  To pull new external images, you may need to configure a proxy: 
    > kubectl.sha256: 65 B / 65 B [--------------------------] 100.00% ? p/s 0s
    > kubeadm.sha256: 65 B / 65 B [--------------------------] 100.00% ? p/s 0s
    > kubelet.sha256: 65 B / 65 B [--------------------------] 100.00% ? p/s 0s
    > kubeadm: 37.96 MiB / 37.96 MiB [------------] 100.00% 216.61 KiB p/s 3m0s
    > kubectl: 41.98 MiB / 41.98 MiB [------------] 100.00% 233.34 KiB p/s 3m4s
    > kubelet: 108.01 MiB / 108.01 MiB [---------] 100.00% 408.56 KiB p/s 4m31s

🌟  Enabling addons: default-storageclass, storage-provisioner
🤹  Configuring local host environment ...

❗  The 'none' driver is designed for experts who need to integrate with an existing VM
💡  Most users should use the newer 'docker' driver instead, which does not require root!
📘  For more information, see: https://minikube.sigs.k8s.io/docs/reference/drivers/none/

❗  kubectl and minikube configuration will be stored in /home/vagrant
❗  To use kubectl or minikube commands as your own user, you may need to relocate them. For example, to overwrite your own settings, run:

    ▪ sudo mv /home/vagrant/.kube /home/vagrant/.minikube $HOME
    ▪ sudo chown -R $USER $HOME/.kube $HOME/.minikube

💡  This can also be done automatically by setting the env var CHANGE_MINIKUBE_NONE_USER=true
🏄  Done! kubectl is now configured to use "minikube"

❗  /usr/local/bin/kubectl is v1.13.4, which may be incompatible with Kubernetes v1.18.0.
💡  You can also use 'minikube kubectl -- get pods' to invoke a matching version

$ sudo kubectl get pod -n kube-system
NAME                               READY   STATUS    RESTARTS   AGE
coredns-66bff467f8-5rwm9           1/1     Running   0          2m41s
coredns-66bff467f8-kfsl4           1/1     Running   0          2m41s
etcd-minikube                      1/1     Running   0          2m50s
kube-apiserver-minikube            1/1     Running   0          2m50s
kube-controller-manager-minikube   1/1     Running   0          2m50s
kube-proxy-7wnkw                   1/1     Running   0          2m41s
kube-scheduler-minikube            1/1     Running   0          2m50s
storage-provisioner                1/1     Running   0          2m47s