Add Glossary of Terms/Components

[karlkfi]

We came up with a draft glossary and component communication map below. They need to be cleaned up, added to the docs, and linked to from other docs pages.

K8SM Glossary

• etcd - external file system based registry (HA key/value store)
• apiserver (k8s)
  • provides UI for observing the state of the cluster
  • provides an API for reading desired/current cluster state in the registry/etcd (used by cli)
• scheduler (k8s)
  • compares desired/current state and schedules/binds changes (k8s tasks) via the api server
• kublet (k8s)
  • server/slave node that runs pods
• controller-manager (k8s)
  • runs multiple controllers
    • node
    • endpoint
    • pod replication
• mesos-master (mesos)
  • components:
    • allocator - ?
    • registry (backed by paxos-based replicated log)
  • brokers resources
  • native or language-specific bindings (mesos-go) implement the HTTP libprocess API
• mesos-slave (mesos)
  • run & manage executor task lifecycle isolated by containerizers
  • gateway for task status updates (used by framework)
• framework (mesos)
  • conceptual mesos plugin pattern that consists of two parts:
    • scheduler
    • executor
• executor (mesos)
  • manages executable downloaded by mesos-slave to be run (mesos task)
• containerizer (mesos)
  • run and monitor executors
  • handles generic resource isolation
  • multiple isolator implementations
    • native mesos containerizer (cgroups/namespaces)
      • network isolator
      • cgroups cpu/mem isolator
      • perf isolator (for publishing metrics)
    • docker containerizer uses docker instead
    • custom external containerizer could be configured

Component Communications

• etcd
  • <-> etcd nodes (HA) [optional]
• zookeeper [optional]
  • <-> zookeeper nodes (HA) [optional]
• mesos-master
  • <-> mesos-master nodes (HA) [optional]
  • mesos-slave (libprocess/HTTP)
  • framework scheduler (libprocess/HTTP)
  • zookeeper (ZK)
• mesos-slave
  • mesos-master (libprocess/HTTP)
  • zookeeper
  • containerizer (in-process)
    • executor(s) (libprocess/HTTP)
• apiserver
  • etcd (REST/HTTP)
  • mesos-master via cloudprovider/mesos (HTTP: state.json)
  • zookeeper via mesos-go/detector/zk (ZK)
• controller-manager
  • apiserver (REST/HTTP)
  • mesos-master via cloudprovider/mesos (HTTP: state.json)
  • zookeeper via mesos-go/detector/zk (ZK)
• scheduler
  • etcd (REST/HTTP: scheduler state)
  • mesos-master (libprocess/HTTP)
  • apiserver (REST/HTTP)
  • zookeeper via mesos-go/detector/zk (ZK)

[karlkfi]

It would be great if the component communication section also specified which flag/arguments/configurations were needed to specify that communication. Note: sometimes what the component uses (listens on) is different from what it announces for other components to use, depending on system env (proxies/dns/port-forwarding).

[jdef]

Added to DCOS/certified because this is probably going to be immensely helpful for users running k8s-mesos on dcos.