Docker, what else?

(c) George.

Sylvain Bauza / @sylvainbauza / bauzas (Freenode)

Docker Grenoble meetup

19/03/2015

Kubernetes

In old Greek, "Steersman, helmsman, sailing master"

Φιλοσοφία Βιοῦ Κυβερνήτης
"Love of wisdom is the guide of life"

Docker is not...

1. cluster-centric
2. declarative
3. able to scale and schedule thru a massive deployment

Solution:

Docker Entreprise (Swarm and Compose)

Want a big picture ?

Kubernetes Node

Minion (Or "Kubernetes Node"; the name is evolving) A Docker host running the kubelet and the proxy service.   Pod One or more inter-related (linked) Docker containers.   Cluster A collection of one or more Minions.

Minion Daemon:
kubernetes-kubelet

• Primary responsilibity: pod management
• Maintain a record of pod state
• Take instructions from the cluster master

Minion Daemon:
kubernetes-proxy

• Forward requests to the right container
• Load-balance requests
• Ensure minion subnet isolation

etcd

• Highly available key/value data store
• Built-in clustering support
• RAFT consensus-based algorithm for updates

Cluster Management

Kubernetes API RESTful web API for Kubernetes, running on nginx   Scheduler One job: choose minions for pods   Controller Manager Monitoring service for deployed pods   kubecfg (A newer iteration of this is now called kubectl ) CLI for working with a Kubernetes cluster

Replication Controllers

You tell it what you need, it decides which minions to deploy on Constant monitoring; starts and stops pods as necessary to match the count Decoupled from service proxying

kubectl

Get details on resource(s)

$ kubectl get pods|services|rc|...

Create a resource

$ kubectl create -f some/body.[json|yaml]

Resize a ReplicationController

$ kubectl resize --replicas=3 foo

Execute a command on a container

$ kubectl exec -p 123456-7890 -c ruby-container -i -t -- bash -il

The Kubernetes API

• Minions (docker hosts)
• Pods (docker container configurations)
• Services (single, stable name for a set of pods, acts as a LB)
• Replication Controllers (manages the lifecycle of the pods)
• Labels

Labels

• A label or consists of a key and a value (also called a selector)
• A pod can have any number of labels; each label must have a unique key
• Examples: service=nginx, environment=prod, tier=frontend

Pods

{
  "id": "redis-master-pod",
  "kind": "Pod",
  "apiVersion": "v1beta1",
  "desiredState": {
    "manifest": {
      "version": "v1beta1",
      "id": "redis-master-pod",
      "containers": [{
        "name": "redis-master",
        "image": "gurpartap/redis",
        "ports": [{ "name": "redis-server", "containerPort": 6379 }]
      }]
    }
  },
  "labels": {"name": "redis"}
}
		        	

Services

{
  "id": "redis-master",
  "kind": "Service",
  "apiVersion": "v1beta1",
  "port": 8888,
  "containerPort": 6379,
  "selector": {
    "name": "redis"
  },
  "labels": {"name": "redis"}
}
		        	

Service env vars

REDIS_PORT='tcp://10.0.29.247:8888'
REDIS_PORT_6379_TCP='tcp://10.0.29.247:8888'
REDIS_PORT_6379_TCP_ADDR='10.0.29.247'
REDIS_PORT_6379_TCP_PORT='8888'
REDIS_PORT_6379_TCP_PROTO='tcp'
REDIS_SERVICE_PORT='8888'
REDIS_SERVICE_HOST='10.0.29.247'
		        	

Replication Controllers

{
  "id": "redisSlaveController",
  "kind": "ReplicationController",
  "apiVersion": "v1beta1",
  "desiredState": {
    "replicas": 2,
    "replicaSelector": {"name": "redisslave"},
    "podTemplate": {
      "desiredState": {
         "manifest": {
           "version": "v1beta1",
           "id": "redisSlaveController",
           "containers": [{
             "name": "slave",
             "image": "brendanburns/redis-slave",
             "ports": [{"containerPort": 6379, "hostPort": 8888}]
           }]
         }
       },
       "labels": {"name": "redisslave"}
      }},
  "labels": {"name": "redisslave"}
}
		        	

Cockpit UI (beta)

That's it !

Questions ?