discovery

README

Discovery

Docker Swarm comes with multiple Discovery backends

Examples

Using the hosted discovery service

# create a cluster
$ swarm create
6856663cdefdec325839a4b7e1de38e8

# on each of your nodes, start the swarm agent
#  <node_ip> doesn't have to be public (eg. 192.168.0.X),
#  as long as the other nodes can reach it, it is fine.
$ swarm join --discovery token://6856663cdefdec325839a4b7e1de38e8 --addr=<node_ip:2375>

# start the manager on any machine or your laptop
$ swarm manage --discovery token://6856663cdefdec325839a4b7e1de38e8 -H=<swarm_ip:swarm_port>

# use the regular docker cli
$ docker -H <swarm_ip:swarm_port> info
$ docker -H <swarm_ip:swarm_port> run ... 
$ docker -H <swarm_ip:swarm_port> ps 
$ docker -H <swarm_ip:swarm_port> logs ...
...

# list nodes in your cluster
$ swarm list --discovery token://6856663cdefdec325839a4b7e1de38e8
http://<node_ip:2375>

Using a static file describing the cluster

# for each of your nodes, add a line to a file
#  <node_ip> doesn't have to be public (eg. 192.168.0.X),
#  as long as the other nodes can reach it, it is fine.
$ echo <node_ip:2375> >> /tmp/my_cluster

# start the manager on any machine or your laptop
$ swarm manage --discovery file:///tmp/my_cluster -H=<swarm_ip:swarm_port>

# use the regular docker cli
$ docker -H <swarm_ip:swarm_port> info
$ docker -H <swarm_ip:swarm_port> run ... 
$ docker -H <swarm_ip:swarm_port> ps 
$ docker -H <swarm_ip:swarm_port> logs ...
...

# list nodes in your cluster
$ swarm list --discovery file:///tmp/my_cluster
http://<node_ip:2375>

Using etcd

# on each of your nodes, start the swarm agent
#  <node_ip> doesn't have to be public (eg. 192.168.0.X),
#  as long as the other nodes can reach it, it is fine.
$ swarm join --discovery etcd://<etcd_ip>/>path> --addr=<node_ip:2375>

# start the manager on any machine or your laptop
$ swarm manage --discovery etcd://<etcd_ip>/>path> -H=<swarm_ip:swarm_port>

# use the regular docker cli
$ docker -H <swarm_ip:swarm_port> info
$ docker -H <swarm_ip:swarm_port> run ... 
$ docker -H <swarm_ip:swarm_port> ps 
$ docker -H <swarm_ip:swarm_port> logs ...
...

# list nodes in your cluster
$ swarm list --discovery etcd://<etcd_ip>/>path>
http://<node_ip:2375>

Contributing

Contributing a new discovery backend is easy, simply implements this interface:

type DiscoveryService interface {
     Initialize(string, int) error
     Fetch() ([]string, error)
     Watch(WatchCallback)
     Register(string) error
}

######Initialize take the --dicovery withtout the scheme and a heartbeat (in seconds)

######Fetch returns the list of all the nodes from the discovery

######Watch triggers an update (Fetch),it can happen either via a timer (like token) or use backend specific features (like etcd)

######Register add a new node to the discovery

Documentation

Index

• Variables
• func Register(scheme string, d DiscoveryService) error
• type DiscoveryService
  • func New(rawurl string, heartbeat int) (DiscoveryService, error)
• type Node
  • func NewNode(url string) *Node
  • func (n Node) String() string
• type WatchCallback

Variables

var (
	ErrNotSupported   = errors.New("discovery service not supported")
	ErrNotImplemented = errors.New("not implemented in this discovery service")
)

Functions

func Register

func Register(scheme string, d DiscoveryService) error

Types

type DiscoveryService

type DiscoveryService interface {
	Initialize(string, int) error
	Fetch() ([]*Node, error)
	Watch(WatchCallback)
	Register(string) error
}

func New

func New(rawurl string, heartbeat int) (DiscoveryService, error)

type Node

type Node struct {
	// contains filtered or unexported fields
}

func NewNode

func NewNode(url string) *Node

func (Node) String

func (n Node) String() string

type WatchCallback

type WatchCallback func(nodes []*Node)