forked from coredns/coredns
/
setup.go
92 lines (77 loc) · 1.76 KB
/
setup.go
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package metrics
import (
"net"
"sync"
"github.com/coredns/coredns/core/dnsserver"
"github.com/coredns/coredns/middleware"
"github.com/mholt/caddy"
)
func init() {
caddy.RegisterPlugin("prometheus", caddy.Plugin{
ServerType: "dns",
Action: setup,
})
}
func setup(c *caddy.Controller) error {
m, err := prometheusParse(c)
if err != nil {
return middleware.Error("prometheus", err)
}
dnsserver.GetConfig(c).AddMiddleware(func(next middleware.Handler) middleware.Handler {
m.Next = next
return m
})
// During restarts we will keep this handler running.
metricsOnce.Do(func() {
c.OncePerServerBlock(m.OnStartup)
c.OnFinalShutdown(m.OnShutdown)
})
return nil
}
func prometheusParse(c *caddy.Controller) (*Metrics, error) {
var (
met = &Metrics{Addr: addr, zoneMap: make(map[string]bool)}
err error
)
for c.Next() {
if len(met.ZoneNames()) > 0 {
return met, c.Err("can only have one metrics module per server")
}
for _, z := range c.ServerBlockKeys {
met.AddZone(middleware.Host(z).Normalize())
}
args := c.RemainingArgs()
switch len(args) {
case 0:
case 1:
met.Addr = args[0]
_, _, e := net.SplitHostPort(met.Addr)
if e != nil {
return met, e
}
default:
return met, c.ArgErr()
}
for c.NextBlock() {
switch c.Val() {
case "address":
args = c.RemainingArgs()
if len(args) != 1 {
return met, c.ArgErr()
}
met.Addr = args[0]
// expecting something that resembles a host-port
_, _, e := net.SplitHostPort(met.Addr)
if e != nil {
return met, e
}
default:
return met, c.Errf("unknown item: %s", c.Val())
}
}
}
return met, err
}
var metricsOnce sync.Once
// Addr is the address the where the metrics are exported by default.
const addr = "localhost:9153"