How to run a local kubernetes
We will go through a quick install of kubernetes on top of docker.
We won't detail kubernetes so much in this post.
We will use the official docker getting started guide.
summary
update
- 16/07 Added scripts for windows
prerequisites
You need docker.
kubernetes services
Kubernetes run with 5 services :
- kube-apiserver
- kube-scheduler
- kube-controller-manager
- kubelet
- kube-proxy
It also needs etcd to run.
On cluster, we launch apiserver/ kube-scheduler/ kube-controller-manager on the master. Kubelet and kube-proxy run on each nodes.
Here, as we run locally, we just start all the services
presentation
etcd
etcd is a distributed, consistent key-value store for shared configuration and service discovery, with a focus on being:
- Simple: curl'able user facing API (HTTP+JSON)
- Secure: optional SSL client cert authentication
- Fast: benchmarked 1000s of writes/s per instance
- Reliable: properly distributed using Raft
etcd is written in Go and uses the Raft consensus algorithm to manage a highly-available replicated log.
You can find the official documentation here.
This command will run the etcd container :
| COMMAND | Info
|-------------------------------------------------|------------------------------
| docker run | run a container
| --net=host | share network with host
| -d | as a daemon
| gcr.io/google_containers/etcd:2.0.9 | from the google etcd image
| /usr/local/bin/etcd | run this command at startup
| --addr=127.0.0.1:4001 |
| --bind-addr=0.0.0.0:4001 |
| --data-dir=/var/etcd/data |
master and kubelet
this is four services :
- api-server (master service)
- scheduler (master service)
- controller-manager (master service)
- kubelet (node service)
| COMMAND | Info
|-------------------------------------------------|---------------------------------------
| docker run | run a container
| --net=host | share network with host
| -d | as a daemon
| -v /var/run/docker.sock:/var/run/docker.sock | share a volume host:container
| gcr.io/google_containers/hyperkube:v0.21.2 | from the hyperkube image
| /hyperkube | run this command at startup with args
| kubelet | run kubelet
| --api_servers=http://localhost:8080 | address of apiserver
| --v=2 | verbose
| --address=0.0.0.0 |
| --enable_server |
| --hostname_override=127.0.0.1 |
| --config=/etc/kubernetes/manifests | manifests path for configuration
kube proxy
| COMMAND | Info
|---------------------------------------------------|-----------------------------------------
| docker run | run a container
| -d | as a daemon/service
| --net=host | share network with host
| --privileged | root
| gcr.io/google_containers/hyperkube:v0.21.2 | from the hyperkube image
| /hyperkube | run this command at startup with args
| proxy | run proxy
| --master=http://127.0.0.1:8080 | address of master
| --v=2 | verbose
Run it
Go to a chosen folder and copy/paste this to a terminal to generate the scripts
cat <<EOF >> start.sh
# etcd
docker run \
--net=host \
-d \
gcr.io/google_containers/etcd:2.0.9 \
/usr/local/bin/etcd \
--addr=127.0.0.1:4001 \
--bind-addr=0.0.0.0:4001 \
--data-dir=/var/etcd/data
# kubernetes
docker run \
--net=host \
-d \
-v /var/run/docker.sock:/var/run/docker.sock \
gcr.io/google_containers/hyperkube:v0.21.2 \
/hyperkube \
kubelet \
--api_servers=http://localhost:8080 \
--v=2 \
--address=0.0.0.0 \
--enable_server \
--hostname_override=127.0.0.1 \
--config=/etc/kubernetes/manifests
# proxy
docker run \
-d \
--net=host \
--privileged \
gcr.io/google_containers/hyperkube:v0.21.2 \
/hyperkube \
proxy \
--master=http://127.0.0.1:8080 \
--v=2
EOF
cat <<EOF >> stop.sh
docker kill \`docker ps -aq\`
EOF
chmod 755 start.sh stop.sh
Now you just have to :
./start.sh
And control that (after a download time), you have something like this :
➜ linux-k8s docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f5e0f1708918 gcr.io/google_containers/hyperkube:v0.21.2 /hyperkube schedule 4 minutes ago Up 4 minutes k8s_scheduler.b725e775_k8s-master-127.0.0.1_default_9b44830745c166dfc6d027b0fc2df36d_c27e095d
99685b4928cc gcr.io/google_containers/hyperkube:v0.21.2 /hyperkube apiserve 4 minutes ago Up 4 minutes k8s_apiserver.70750283_k8s-master-127.0.0.1_default_9b44830745c166dfc6d027b0fc2df36d_1c37abde
eef830aa7a6d gcr.io/google_containers/hyperkube:v0.21.2 /hyperkube controll 4 minutes ago Up 4 minutes k8s_controller-manager.aad1ee8f_k8s-master-127.0.0.1_default_9b44830745c166dfc6d027b0fc2df36d_be5ce858
8bdfe3cc9509 gcr.io/google_containers/pause:0.8.0 /pause 4 minutes ago Up 4 minutes k8s_POD.e4cc795_k8s-master-127.0.0.1_default_9b44830745c166dfc6d027b0fc2df36d_79dea59d
28760651e24e gcr.io/google_containers/hyperkube:v0.21.2 /hyperkube proxy -- 4 minutes ago Up 4 minutes backstabbing_lovelace
663bfd8d97a5 gcr.io/google_containers/hyperkube:v0.21.2 /hyperkube kubelet 4 minutes ago Up 4 minutes goofy_einstein
d549b25c97c4 gcr.io/google_containers/etcd:2.0.9 /usr/local/bin/etcd 4 minutes ago Up 4 minutes dreamy_kilby
We can see here our services.
Make it do something
To communicate with the kubernetes services, we can use CLI, API or SDK.
We will use the CLI solution : kubectl.
You can download it and install it, but we will here use a container for that.
Just copy/paste this in your terminal :
cat <<EOF >> run_kubectl.sh
docker run \
-ti \
--net=host \
tdeheurles/gcloud-tools:latest \
bash
EOF
chmod 755 run_kubectl.sh
./run_kubectl.sh
tdeheurles/gcloud-tools container is just a container where gcloud sdk is installed.
you should have a prompt when running the run_kubetcl.sh script, and writing kubectl should give you the help :
➜ ./run_kubectl.sh
root@VM-Ubuntu:/# kubectl
kubectl controls the Kubernetes cluster manager.
Find more information at https://github.com/GoogleCloudPlatform/kubernetes.
Usage:
kubectl [flags]
kubectl [command]
Available Commands:
get Display one or many resources
describe ...
[...]
So create a nginx container :
➜ kubectl -s http://localhost:8080 run-container nginx --image=nginx --port=80
CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS
nginx nginx nginx run=nginx 1
and expose it by creating a service :
➜ kubectl expose rc nginx --port=80
NAME LABELS SELECTOR IP(S) PORT(S)
nginx run=nginx run=nginx 80/TCP
after a short moment, kubectl get services should show you the IP where you can join the nginx. A curl the_ip_of_service should show you a nginx response :
➜ kubectl get services
NAME LABELS SELECTOR IP(S) PORT(S)
kubernetes component=apiserver,provider=kubernetes <none> 10.0.0.1 443/TCP
nginx run=nginx run=nginx 10.0.0.208 80/TCP
➜ curl 10.0.0.208
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
width: 35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href=http://nginx.org/>nginx.org</a>.<br/>
Commercial support is available at
<a href=http://nginx.com/>nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
cool ^^
Our service is running ^^
windows
To run docker on windows, you can follow this post.
Then, things are very similar :
$etcd_version="2.0.9"
$kubernetes_version="v0.21.2"
# etcd
docker run `
--net=host `
-d `
gcr.io/google_containers/etcd:$etcd_version `
/usr/local/bin/etcd `
--addr=127.0.0.1:4001 `
--bind-addr=0.0.0.0:4001 `
--data-dir=/var/etcd/data
# kubernetes
docker run `
--net=host `
-d `
-v /var/run/docker.sock:/var/run/docker.sock `
gcr.io/google_containers/hyperkube:$kubernetes_version `
/hyperkube `
kubelet `
--api_servers=http://localhost:8080 `
--v=2 `
--address=0.0.0.0 `
--enable_server `
--hostname_override=127.0.0.1 `
--config=/etc/kubernetes/manifests
# proxy
docker run `
-d `
--net=host `
--privileged `
gcr.io/google_containers/hyperkube:$kubernetes_version `
/hyperkube `
proxy `
--master=http://127.0.0.1:8080 `
--v=2
And as with linux, we can run kubectl with tdeheurles/gcloud-tools :
docker run `
-ti `
--net=host `
tdeheurles/gcloud-tools:latest `
bash
root@boot2docker:/# kubectl cluster-info
Kubernetes master is running at http://localhost:8080
Just know that kubernetes run locally in the VM.