CoreOS: an introduction
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Transcript of CoreOS: an introduction
About MeCTO/CO-FOUNDERsystems engineer
@brandonphilipsgithub.com/philips
What is CoreOS?
What is CoreOS?
Why build CoreOS?
reduce API contracts
minimal
kernelsystemdetcdsshdocker
pythonjavanginxmysqlopenssl
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pythonjavanginxmysqlopenssl
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kernelsystemdetcdsshdocker
pythonopenssl-A app1
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javaopenssl-B app2
javaopenssl-B app3
kernelsystemdetcdsshdocker
CoreOS
pythonopenssl-A app1
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javaopenssl-B app2
javaopenssl-B app3
CoreOS
container
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container
container
manual updates
automatic updates
automatic updates
atomic with rollback
auto updates
run and isolate apps
containers
pid nsisolated pid 1
user nsisolated uid 0
network nsisolated netdev
mount nsisolated /
cgroupsmanage resources
cgroupscount resources
cgroupslimit resources
docker engine
machines and clusters
configuration
get into the cluster
machine conf
#cloud-config
users: - name: core coreos-ssh-import-github: philips
coreos: etcd: discovery: https://discovery.etcd.io/ba09c units: - name: etcd.service command: start - name: fleet.service command: start
#cloud-config
users: - name: core coreos-ssh-import-github: philips
coreos: etcd: discovery: https://discovery.etcd.io/ba09c units: - name: etcd.service command: start - name: fleet.service command: start
#cloud-config
users: - name: core coreos-ssh-import-github: philips
coreos: etcd: discovery: https://discovery.etcd.io/ba09c units: - name: etcd.service command: start - name: fleet.service command: start
#cloud-config
users: - name: core coreos-ssh-import-github: philips
coreos: etcd: discovery: https://discovery.etcd.io/ba09c units: - name: etcd.service command: start - name: fleet.service command: start
what is running
cluster conf
skydns, discoverd, confd
services
what should run
cluster conf
locksmith
coordination
fleet, kubernetes
scheduling
etcd
/etcdistributed
open source softwarehighly available and reliablesequentially consistentwatchableexposed via HTTPruntime reconfigurable
-X GETGet Wait
-X PUTPut Create CAS
-X DELETEDelete CAD
Available
Available
Available
Unavailable
Available
Leader
Follower
Leader
Follower
Available
Leader
Follower
Temporarily Unavailable
Leader
Follower
Available
Sequential ConsistencyIndex Time
1
1
1
2
GET A @ index 2 -> blocking
GET A @ index 2 -> 2
2
1
1
1
2
GET A @ index 2 -> 2
2
2
etcd guarantees that a get at index X will always return the
same result.
Avoid thinking in terms of real time because with network latency the result is always out-of-date.
Watchable ChangesHTTP Long-poll
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> GET asdf?waitIndex=4&wait=true HTTP/1.1> Accept: */*>< HTTP/1.1 200 OK< Content-Type: application/json< X-Etcd-Index: 3< X-Raft-Index: 97< X-Raft-Term: 0<BLOCK
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> GET asdf?waitIndex=4&wait=true HTTP/1.1> Accept: */*>< HTTP/1.1 200 OK< Content-Type: application/json< X-Etcd-Index: 3< X-Raft-Index: 97< X-Raft-Term: 0<{"action":"set","node":{"key":"/asdf","value":"foobar","modifiedIndex":4,"createdIndex":4}}
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> GET asdf?waitIndex=4&wait=true HTTP/1.1> Accept: */*>< HTTP/1.1 200 OK< Content-Type: application/json< X-Etcd-Index: 4< X-Raft-Index: 516< X-Raft-Term: 0<{"action":"set","node":{"key":"/asdf","value":"foobar","modifiedIndex":4,"createdIndex":4}}
getting work to servers
scheduling
You
Scheduler API
Scheduler
Machine(s)
$ cat foo.service[Service]ExecStart=/usr/bin/sleep 500
$ fleetctl start foo.serviceJob foo.service launched on e1cd2bcd.../172.17.8.101
while true { todo = diff(desState, curState) schedule(todo)}
while true { todo = diff(desState, curState) schedule(todo)}
while true { todo = diff(desState, curState) schedule(todo)}
while true { todo = diff(desState, curState) schedule(todo)}
Talk tomorrow!fleet: systemd for clusters2:30pm Mississippi
Why use CoreOS?
is it ready?stable released
lots of work todo
the future
DEMO?
