README
¶
Cluster leader election using Consul distributed locks
package main
import (
"log"
"time"
"github.com/hashicorp/consul/api"
"github.com/pteich/clusterleader"
)
func main() {
config := api.DefaultConfig()
config.Address = "127.0.0.1:8500"
client, err := api.NewClient(config)
clusterLeader, err := clusterleader.NewClusterleader(client, "testkey", "localhost", 15*time.Second)
if err != nil {
log.Fatal(err)
}
go func() {
for err := range clusterLeader.Errors() {
log.Print(err)
}
}()
// as long as this loop runs we try to become leader
// an isElected event is send on every state change
// best would be to run this loop in a go routine and
// react to whatever we are leader or not
for isElected := range clusterLeader.Election() {
if isElected {
// we are leader
} else {
// not leader
}
}
}
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Clusterleader ¶
Clusterleader uses Consul distributed locks to elect a cluster leader
func New ¶
func New(consulClient *api.Client, key string, node string, waitTime time.Duration) (*Clusterleader, error)
New returns a new Clusterleader instance with a given consul connection
func NewWithDefaultClient ¶
NewDefaultClient uses a default Consul client (which can also be set using Consul env variables)
func (*Clusterleader) Election ¶
func (cl *Clusterleader) Election(ctx context.Context) <-chan bool
Election returns a channel that signals if we are leader or not
func (*Clusterleader) Errors ¶
func (cl *Clusterleader) Errors() <-chan error
Errors returns a channel that receives all errors
func (*Clusterleader) IsLeader ¶
func (cl *Clusterleader) IsLeader() bool
IsLeader just returns if we are leader or not
type DistributedLock ¶
type DistributedLock struct {
// contains filtered or unexported fields
}
DistributedLock describes a lock
func NewDistributedLock ¶
func NewDistributedLock(consulClient *api.Client, prefix string, sessionTTL time.Duration) (*DistributedLock, error)
NewDistributedLock returns an instance with a given Consul client
func NewDistributedLockWithDefaultClient ¶
func NewDistributedLockWithDefaultClient(prefix string, sessionTTL time.Duration) (*DistributedLock, error)
NewDistributedLockWithDefaultClient uses a Consul client with default settings (or values from ENV)
func (*DistributedLock) Lock ¶
func (dl *DistributedLock) Lock(key string, value string, lockWaitTime time.Duration) (<-chan struct{}, error)
Lock tries once to acquire the lock or return an error if it could not get it
func (*DistributedLock) Unlock ¶
func (dl *DistributedLock) Unlock(key string) error
Unlock releases a specific lock
func (*DistributedLock) UnlockAll ¶
func (dl *DistributedLock) UnlockAll()
UnlockAll releases all held locks
Source Files