README
¶
rrdialer
A round robin net dialer.
rrdialer has features below.
- Dials to one of specified hosts by round robin.
- Health checker by Go's function
- MySQL
- TCP
- HTTP
- or Your custom function
Usage
Without healthchecker
A simple usage.
addrs := []string{"host1:8888", "host2:8888"},
da := rrdialer.NewDialer(ctx, addrs, nil)
conn, err := da.Dial("tcp") // connect to host1:8888 or host2:8888
Example for MySQL
go-sql-driver/mysql has an interface to customize dialer.
// upstream addresses
addrs := []string{"slave1:3306", "slave2:3307"},
// health checker
opt := rrdialer.NewOption()
// health checker uses "tcp" as usual
opt.CheckFunc = rrdialer.NewMySQLCheckFunc("test:test@tcp(dummy)/test")
da := rrdialer.NewDialer(ctx, addrs, opt)
// register a custom network "roundrobin" for rrdialer into mysql
dsn := "test:test@roundrobin(dummy)/test"
cfg, _ := mysql.ParseDSN(dsn)
mysql.RegisterDial("roundrobin",
func(_ string) (net.Conn, error) {
return da.DialTimeout("tcp", cfg.Timeout)
},
)
// connect via rrdialer
db, _ := sql.Open("mysql", dsn)
Example for TCP
addrs := []string{"host1:8888", "host2:8888"},
opt := rrdialer.NewOption()
opt.CheckFunc = rrdialer.NewTCPCheckFunc()
da := rrdialer.NewDialer(ctx, addrs, opt)
conn, err := da.Dial("tcp")
Example for HTTP health check
addrs := []string{"backend1:80", "backend2:80"}
checkReq, _ := http.NewRequest("GET", "http://example.com/ping", nil)
opt := rrdialer.NewOption()
opt.CheckFunc = rrdialer.NewHTTPCheckFunc(checkReq)
da := rrdialer.NewDialer(ctx, addrs, opt)
client := &http.Client{
Transport: &http.Transport{
DialContext: func(ctx context.Context, network, _ string) (net.Conn, error) {
return da.DialContext(ctx, network)
},
Dial: func(network, _ string) (net.Conn, error) {
return da.Dial(network)
},
},
}
// client connects to a server via rrdialer
res, err := client.Get("http://example.com/foo/bar")
LICENSE
The MIT License (MIT)
Copyright (c) 2017 FUJIWARA Shunichiro / (c) 2017 KAYAC Inc.
Documentation
¶
Index ¶
Constants ¶
View Source
const ( DefaultEjectThreshold = 2 DefaultRecoverThreshold = 2 DefaultCheckInterval = 5 * time.Second DefaultCheckTimeout = 5 * time.Second )
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type CheckFunc ¶
func NewHTTPCheckFunc ¶
NewHTTPCheckFunc makes CheckFunc for HTTP server. This func send request to server and check HTTP status code. A status code over 400 makes failure.
func NewMySQLCheckFunc ¶
NewMySQLCheckFunc makes CheckFunc for MySQL server
func NewTCPCheckFunc ¶
func NewTCPCheckFunc() CheckFunc
NewMySQLCheckFunc makes CheckFunc for general TCP server This func tries connect and close simply.
type Dialer ¶
type Dialer struct {
// contains filtered or unexported fields
}
func (*Dialer) DialContext ¶
DialContext dials to an available address in Dialer via network with context.
func (*Dialer) DialTimeout ¶
DialContext dials to an available address in Dialer via network with timeout.
type Logger ¶
type Logger interface {
Println(v ...interface{})
Printf(format string, v ...interface{})
}
Logger is an interface for rrdialer
type Option ¶
type Option struct {
EjectThreshold int // When health check failed count reached EjectThreshold, upstream is marked as down until pass health check
RecoverThreshold int // When health check succeeded count reached RecoverThreshold, upstream is marked as alive
CheckInterval time.Duration // health check interval
CheckTimeout time.Duration // health check timeout
Logger Logger
CheckFunc CheckFunc
NextUpstream bool // Try next upstream when dial failed
}
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