7c59d39834
* middleware/metrics: survive restart Keep the handler running during restart. Stopping and starting the handler results in "address in use" - sometimes, meaning the reload will be flaky. In turn this behavior means any changes to the monitor stanza are not picked up. * remove resync
92 lines
1.8 KiB
Go
92 lines
1.8 KiB
Go
package metrics
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import (
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"net"
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"sync"
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"github.com/miekg/coredns/core/dnsserver"
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"github.com/miekg/coredns/middleware"
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"github.com/mholt/caddy"
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)
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func init() {
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caddy.RegisterPlugin("prometheus", caddy.Plugin{
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ServerType: "dns",
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Action: setup,
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})
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}
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func setup(c *caddy.Controller) error {
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m, err := prometheusParse(c)
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if err != nil {
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return middleware.Error("prometheus", err)
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}
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dnsserver.GetConfig(c).AddMiddleware(func(next middleware.Handler) middleware.Handler {
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m.Next = next
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return m
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})
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// During restarts we will keep this handler running.
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metricsOnce.Do(func() {
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c.OncePerServerBlock(m.OnStartup)
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c.OnFinalShutdown(m.OnShutdown)
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})
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return nil
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}
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func prometheusParse(c *caddy.Controller) (*Metrics, error) {
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var (
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met = &Metrics{Addr: addr, zoneMap: make(map[string]bool)}
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err error
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)
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for c.Next() {
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if len(met.ZoneNames()) > 0 {
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return met, c.Err("can only have one metrics module per server")
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}
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for _, z := range c.ServerBlockKeys {
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met.AddZone(middleware.Host(z).Normalize())
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}
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args := c.RemainingArgs()
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switch len(args) {
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case 0:
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case 1:
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met.Addr = args[0]
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_, _, e := net.SplitHostPort(met.Addr)
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if e != nil {
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return met, e
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}
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default:
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return met, c.ArgErr()
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}
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for c.NextBlock() {
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switch c.Val() {
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case "address":
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args = c.RemainingArgs()
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if len(args) != 1 {
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return met, c.ArgErr()
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}
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met.Addr = args[0]
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// expecting something that resembles a host-port
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_, _, e := net.SplitHostPort(met.Addr)
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if e != nil {
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return met, e
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}
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default:
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return met, c.Errf("unknown item: %s", c.Val())
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}
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}
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}
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return met, err
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}
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var metricsOnce sync.Once
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// Addr is the address the where the metrics are exported by default.
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const addr = "localhost:9153"
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