Update more metrics names (#3799)

The subsystem of a metric must be it's plugin name. "dns" is reserved
for the core. Use a const convention to avoid copy-paste mistakes in
naming.

Fix dns64 and acl plugin.

Signed-off-by: Ben Kochie <superq@gmail.com>

plugin/acl/README.md

@@ -73,8 +73,8 @@ example.org {
 
 If monitoring is enabled (via the _prometheus_ plugin) then the following metrics are exported:
 
-- `coredns_dns_blocked_requests_total{server, zone}` - counter of DNS requests being blocked.
+- `coredns_acl_blocked_requests_total{server, zone}` - counter of DNS requests being blocked.
 
-- `coredns_dns_allowed_requests_total{server}` - counter of DNS requests being allowed.
+- `coredns_acl_allowed_requests_total{server}` - counter of DNS requests being allowed.
 
 The `server` and `zone` labels are explained in the _metrics_ plugin documentation.

plugin/acl/metrics.go

@@ -10,15 +10,15 @@ var (
 	// RequestBlockCount is the number of DNS requests being blocked.
 	RequestBlockCount = prometheus.NewCounterVec(prometheus.CounterOpts{
 		Namespace: plugin.Namespace,
-		Subsystem: "dns",
-		Name:      "acl_blocked_requests_total",
+		Subsystem: pluginName,
+		Name:      "blocked_requests_total",
 		Help:      "Counter of DNS requests being blocked.",
 	}, []string{"server", "zone"})
 	// RequestAllowCount is the number of DNS requests being Allowed.
 	RequestAllowCount = prometheus.NewCounterVec(prometheus.CounterOpts{
 		Namespace: plugin.Namespace,
-		Subsystem: "dns",
-		Name:      "acl_allowed_requests_total",
+		Subsystem: pluginName,
+		Name:      "allowed_requests_total",
 		Help:      "Counter of DNS requests being allowed.",
 	}, []string{"server"})
 )

plugin/acl/setup.go

@@ -13,7 +13,9 @@ import (
 	"github.com/miekg/dns"
 )
 
-func init() { plugin.Register("acl", setup) }
+const pluginName = "acl"
+
+func init() { plugin.Register(pluginName, setup) }
 
 func newDefaultFilter() *iptree.Tree {
 	defaultFilter := iptree.NewTree()
@@ -27,7 +29,7 @@ func newDefaultFilter() *iptree.Tree {
 func setup(c *caddy.Controller) error {
 	a, err := parse(c)
 	if err != nil {
-		return plugin.Error("acl", err)
+		return plugin.Error(pluginName, err)
 	}
 
 	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {