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middleware/metrics: allow multiple listeners

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There was no inherent reason *not* to allow multiple listeners for the
monitoring data. Actually enforcing only one listener lead to more code
then just allowing multiple. It's probably not what you want; but
CoreDNS is happy to oblige.
This commit is contained in:
Miek Gieben
2017-04-12 10:10:57 +00:00
parent 2196dde9da
commit c262946009
2 changed files with 35 additions and 9 deletions
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4
middleware/metrics/README.md
View File

@@ -49,5 +49,5 @@ prometheus localhost:9253
# Bugs # Bugs
When reloading, we keep the handler running, meaning that any changes to the handler aren't picked When reloading, we keep the handler running, meaning that any changes to the handler's address
up. You'll need to restart CoreDNS for that to happen. aren't picked up. You'll need to restart CoreDNS for that to happen.

40
middleware/metrics/setup.go
View File

@@ -2,7 +2,6 @@ package metrics
import ( import (
"net" "net"
"sync"
"github.com/coredns/coredns/core/dnsserver" "github.com/coredns/coredns/core/dnsserver"
"github.com/coredns/coredns/middleware" "github.com/coredns/coredns/middleware"
@@ -15,6 +14,8 @@ func init() {
ServerType: "dns", ServerType: "dns",
Action: setup, Action: setup,
}) })
uniqAddr = addrs{a: make(map[string]int)}
} }
func setup(c *caddy.Controller) error { func setup(c *caddy.Controller) error {
@@ -28,11 +29,14 @@ func setup(c *caddy.Controller) error {
return m return m
}) })
// During restarts we will keep this handler running. for a, v := range uniqAddr.a {
metricsOnce.Do(func() { if v == todo {
c.OncePerServerBlock(m.OnStartup) // During restarts we will keep this handler running, BUG.
c.OnFinalShutdown(m.OnShutdown) c.OncePerServerBlock(m.OnStartup)
}) }
uniqAddr.a[a] = done
}
c.OnFinalShutdown(m.OnShutdown)
return nil return nil
} }
@@ -43,6 +47,10 @@ func prometheusParse(c *caddy.Controller) (*Metrics, error) {
err error err error
) )
defer func() {
uniqAddr.SetAddress(met.Addr)
}()
for c.Next() { for c.Next() {
if len(met.ZoneNames()) > 0 { if len(met.ZoneNames()) > 0 {
return met, c.Err("can only have one metrics module per server") return met, c.Err("can only have one metrics module per server")
@@ -86,7 +94,25 @@ func prometheusParse(c *caddy.Controller) (*Metrics, error) {
return met, err return met, err
} }
var metricsOnce sync.Once var uniqAddr addrs
// Keep track on which addrs we listen, so we only start one listener.
type addrs struct {
a map[string]int
}
func (a *addrs) SetAddress(addr string) {
// If already there and set to done, we've already started this listener.
if a.a[addr] == done {
return
}
a.a[addr] = todo
}
// Addr is the address the where the metrics are exported by default. // Addr is the address the where the metrics are exported by default.
const addr = "localhost:9153" const addr = "localhost:9153"
const (
todo = 1
done = 2
)