Kubernetes
Kubernetes is a set of processes running on several machines. It follows master worker patterns. One node is master and left are workers.
| Master node | Work node |
|---|---|
| Config store | Docker runtime |
| API server | kubelet |
| Controller manager | Network proxy(kube-proxy) |
| Controllers | Monitoring |
| Scheduler | Pods |
The processes take the responsibilities of
- (master node) handling API requests from kubectl
- (master node) scheduling pods to run on worker nodes
- running a pod on the worker node
- (worker node) monitoring and networking
etcd is the distributed key value database implemented based on Raft consensus mechanism that kubernetes uses to store configuration data, system state, and metadata.
For example, kubectl get xyz command is read from etcd store. kubectl create will create an entry in etcd.
etcd vs. consul, which one is better?
Since etcd is just a simple distributed kv database, consul provides additional features like healthcheck and has built-in service discovery. consul is more like a solution.