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/
forward.go
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/
forward.go
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package main
import (
"bufio"
"flag"
"fmt"
"math/rand"
"net"
"net/http"
"net/url"
"os"
"strings"
"time"
"github.com/go-kit/kit/log"
"github.com/go-kit/kit/log/level"
"github.com/pkg/errors"
"github.com/prometheus/client_golang/prometheus"
)
func runForward(args []string) error {
flagset := flag.NewFlagSet("forward", flag.ExitOnError)
var (
debug = flagset.Bool("debug", false, "debug logging")
apiAddr = flagset.String("api", "", "listen address for forward API (and metrics)")
prefixes = stringslice{}
)
flagset.Var(&prefixes, "prefix", "prefix annotated on each log record (repeatable)")
flagset.Usage = usageFor(flagset, "oklog forward [flags] <ingester> [<ingester>...]")
if err := flagset.Parse(args); err != nil {
return err
}
args = flagset.Args()
if len(args) <= 0 {
return errors.New("specify at least one ingest address as an argument")
}
// Logging.
var logger log.Logger
{
logLevel := level.AllowInfo()
if *debug {
logLevel = level.AllowAll()
}
logger = log.NewLogfmtLogger(os.Stderr)
logger = log.With(logger, "ts", log.DefaultTimestampUTC)
logger = level.NewFilter(logger, logLevel)
}
// Instrumentation.
forwardBytes := prometheus.NewCounter(prometheus.CounterOpts{
Namespace: "oklog",
Name: "forward_bytes_total",
Help: "Bytes forwarded.",
})
forwardRecords := prometheus.NewCounter(prometheus.CounterOpts{
Namespace: "oklog",
Name: "forward_records_total",
Help: "Records forwarded.",
})
disconnects := prometheus.NewCounter(prometheus.CounterOpts{
Namespace: "oklog",
Name: "forward_disconnects",
Help: "Number of times forwarder is disconnected from ingester.",
})
shortWrites := prometheus.NewCounter(prometheus.CounterOpts{
Namespace: "oklog",
Name: "forward_short_writes",
Help: "Number of times forwarder performs a short write to the ingester.",
})
prometheus.MustRegister(
forwardBytes,
forwardRecords,
disconnects,
shortWrites,
)
// For now, just a quick-and-dirty metrics server.
if *apiAddr != "" {
apiNetwork, apiAddress, _, _, err := parseAddr(*apiAddr, defaultAPIPort)
if err != nil {
return err
}
apiListener, err := net.Listen(apiNetwork, apiAddress)
if err != nil {
return err
}
go func() {
mux := http.NewServeMux()
registerMetrics(mux)
registerProfile(mux)
registerHealthCheck(mux)
panic(http.Serve(apiListener, mux))
}()
}
// Parse URLs for forwarders.
var urls []*url.URL
for _, addr := range args {
schema, host, _, _, err := parseAddr(addr, defaultFastPort)
if err != nil {
return errors.Wrap(err, "parsing ingest address")
}
u, err := url.Parse(fmt.Sprintf("%s://%s", schema, host))
if err != nil {
return errors.Wrap(err, "parsing ingest URL")
}
if _, _, err := net.SplitHostPort(u.Host); err != nil {
return errors.Wrapf(err, "couldn't split host:port")
}
urls = append(urls, u)
}
// Construct the prefix expression.
var prefix string
if len(prefixes) > 0 {
prefix = strings.Join(prefixes, " ") + " "
}
// Shuffle the order.
rand.Seed(time.Now().UnixNano())
for i := range urls {
j := rand.Intn(i + 1)
urls[i], urls[j] = urls[j], urls[i]
}
// Build a scanner for the input, and the last record we scanned.
// These both outlive any individual connection to an ingester.
// TODO(pb): have flag for backpressure vs. drop
var (
s = bufio.NewScanner(os.Stdin)
backoff = time.Duration(0)
)
// Enter the connect and forward loop. We do this forever.
for ; ; urls = append(urls[1:], urls[0]) { // rotate thru URLs
// We gonna try to connect to this first one.
target := urls[0]
host, port, err := net.SplitHostPort(target.Host)
if err != nil {
return errors.Wrapf(err, "unexpected error")
}
// Support e.g. "tcp+dnssrv://host:port"
fields := strings.SplitN(target.Scheme, "+", 2)
if len(fields) == 2 {
proto, suffix := fields[0], fields[1]
switch suffix {
case "dns", "dnsip":
ips, err := net.LookupIP(host)
if err != nil {
level.Warn(logger).Log("LookupIP", host, "err", err)
backoff = exponential(backoff)
time.Sleep(backoff)
continue
}
host = ips[rand.Intn(len(ips))].String()
target.Scheme, target.Host = proto, net.JoinHostPort(host, port)
case "dnssrv":
_, records, err := net.LookupSRV("", proto, host)
if err != nil {
level.Warn(logger).Log("LookupSRV", host, "err", err)
backoff = exponential(backoff)
time.Sleep(backoff)
continue
}
host = records[rand.Intn(len(records))].Target
target.Scheme, target.Host = proto, net.JoinHostPort(host, port) // TODO(pb): take port from SRV record?
case "dnsaddr":
names, err := net.LookupAddr(host)
if err != nil {
level.Warn(logger).Log("LookupAddr", host, "err", err)
backoff = exponential(backoff)
time.Sleep(backoff)
continue
}
host = names[rand.Intn(len(names))]
target.Scheme, target.Host = proto, net.JoinHostPort(host, port)
default:
level.Warn(logger).Log("unsupported_scheme_suffix", suffix, "using", proto)
target.Scheme = proto // target.Host stays the same
}
}
level.Debug(logger).Log("raw_target", urls[0].String(), "resolved_target", target.String())
conn, err := net.Dial(target.Scheme, target.Host)
if err != nil {
level.Warn(logger).Log("Dial", target.String(), "err", err)
backoff = exponential(backoff)
time.Sleep(backoff)
continue
}
ok := s.Scan()
for ok {
// We enter the loop wanting to write s.Text() to the conn.
record := fmt.Sprintf("%s%s\n", prefix, s.Text())
if n, err := fmt.Fprintf(conn, record); err != nil {
disconnects.Inc()
level.Warn(logger).Log("disconnected_from", target.String(), "due_to", err)
break
} else if n < len(record) {
shortWrites.Inc()
level.Warn(logger).Log("short_write_to", target.String(), "n", n, "less_than", len(record))
break // TODO(pb): we should do something more sophisticated here
}
// Only once the write succeeds do we scan the next record.
backoff = 0 // reset the backoff on a successful write
forwardBytes.Add(float64(len(record)))
forwardRecords.Inc()
ok = s.Scan()
}
if !ok {
level.Info(logger).Log("stdin", "exhausted", "due_to", s.Err())
return nil
}
}
}
func exponential(d time.Duration) time.Duration {
const (
min = 16 * time.Millisecond
max = 1024 * time.Millisecond
)
d *= 2
if d < min {
d = min
}
if d > max {
d = max
}
return d
}