main.go
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// design touchstones
// configured entirely via environment variables
// minimal configurable options
// a single global cluster
// easy cluster formation
// todo
// dns resolver for services
package main
import (
"log"
"os"
"strings"
"time"
"github.com/hashicorp/memberlist"
"github.com/hashicorp/serf/serf"
)
func main() {
config := readConfig()
agent := setupAgent(config)
if err := agent.Start(); err != nil {
log.Panic(err)
}
defer agent.Shutdown()
// join any specified startup nodes
if err := startupJoin(config, agent); err != nil {
log.Panic(err)
}
// handleSignals(config, agent)
}
func readConfig() *Config {
config := DefaultConfig()
if os.Getenv("CASCADE_BIND") != "" {
config.BindAddr = os.Getenv("CASCADE_BIND")
}
// CASCADE_JOIN=127.0.0.1,127.0.0.5
if os.Getenv("CASCADE_JOIN") != "" {
config.StartJoin = strings.Split(os.Getenv("CASCADE_JOIN"), ",")
}
return config
}
func startupJoin(config *Config, agent *Agent) error {
if len(config.StartJoin) == 0 {
return nil
}
log.Printf("Joining cluster...")
n, err := agent.Join(config.StartJoin)
if err != nil {
return err
}
log.Printf("Join completed. Synced with %d initial agents", n)
return nil
}
func setupAgent(config *Config) *Agent {
bindIP, bindPort, err := config.AddrParts(config.BindAddr)
if err != nil {
log.Panic(err)
}
serfConfig := serf.DefaultConfig()
serfConfig.MemberlistConfig.BindAddr = bindIP
serfConfig.MemberlistConfig.BindPort = bindPort
serfConfig.MemberlistConfig.AdvertiseAddr = ""
serfConfig.MemberlistConfig.AdvertisePort = 0
serfConfig.ProtocolVersion = uint8(serf.ProtocolVersionMax)
serfConfig.CoalescePeriod = 3 * time.Second
serfConfig.QuiescentPeriod = time.Second
serfConfig.QueryResponseSizeLimit = 1024
serfConfig.QuerySizeLimit = 1024
serfConfig.UserEventSizeLimit = 512
serfConfig.UserCoalescePeriod = 3 * time.Second
serfConfig.UserQuiescentPeriod = time.Second
// TODO: look at reconnect/tombstone settings w more scrutiny
serfConfig.ReconnectInterval = 0
serfConfig.ReconnectTimeout = 0
serfConfig.TombstoneTimeout = 0
serfConfig.BroadcastTimeout = 0
// TODO: what are the implications of true here o_O
serfConfig.EnableNameConflictResolution = true
// hardcode DefaultWANConfig because cascade is designed to be
// used as a single global system.
serfConfig.MemberlistConfig = memberlist.DefaultWANConfig()
serfConfig.MemberlistConfig.BindAddr = bindIP
serfConfig.MemberlistConfig.BindPort = bindPort
agent := Create(serfConfig)
return agent
}