Add extremely noddy counter metrics for !commands

Missing the command type currently. Also, not sure how "nice" this is: we could
probably blob the 3 functions into 1 and use an enum but, meh?

src/github.com/matrix-org/go-neb/goneb.go

@@ -5,6 +5,7 @@ import (
 	"github.com/matrix-org/dugong"
 	"github.com/matrix-org/go-neb/clients"
 	"github.com/matrix-org/go-neb/database"
+	_ "github.com/matrix-org/go-neb/metrics"
 	"github.com/matrix-org/go-neb/polling"
 	_ "github.com/matrix-org/go-neb/realms/github"
 	_ "github.com/matrix-org/go-neb/realms/jira"

src/github.com/matrix-org/go-neb/metrics/metrics.go

@@ -0,0 +1,41 @@
+package metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+var (
+	numIncomingCmds = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "num_incoming_commands_total",
+		Help: "The number of incoming commands from matrix clients",
+	})
+	numSuccessCmds = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "num_success_commands_total",
+		Help: "The number of incoming commands from matrix clients which were successful",
+	})
+	numErrorCmds = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "num_error_commands_total",
+		Help: "The number of incoming commands from matrix clients which failed",
+	})
+)
+
+// IncIncomingCommand increments the incoming command counter (TODO: cmd type)
+func IncIncomingCommand() {
+	numIncomingCmds.Inc()
+}
+
+// IncSuccessCommand increments the success command counter (TODO: cmd type)
+func IncSuccessCommand() {
+	numSuccessCmds.Inc()
+}
+
+// IncErrorCommand increments the error command counter (TODO: cmd type)
+func IncErrorCommand() {
+	numErrorCmds.Inc()
+}
+
+func init() {
+	prometheus.MustRegister(numIncomingCmds)
+	prometheus.MustRegister(numSuccessCmds)
+	prometheus.MustRegister(numErrorCmds)
+}

src/github.com/matrix-org/go-neb/plugin/plugin.go

@@ -3,6 +3,7 @@ package plugin
 import (
 	log "github.com/Sirupsen/logrus"
 	"github.com/matrix-org/go-neb/matrix"
+	"github.com/matrix-org/go-neb/metrics"
 	"github.com/mattn/go-shellwords"
 	"regexp"
 	"strings"
@@ -71,6 +72,7 @@ func runCommandForPlugin(plugin Plugin, event *matrix.Event, arguments []string)
 		"user_id": event.Sender,
 		"command": bestMatch.Path,
 	}).Info("Executing command")
+	metrics.IncIncomingCommand()
 	content, err := bestMatch.Command(event.RoomID, event.Sender, cmdArgs)
 	if err != nil {
 		if content != nil {
@@ -82,7 +84,10 @@ func runCommandForPlugin(plugin Plugin, event *matrix.Event, arguments []string)
 				"args":       cmdArgs,
 			}).Warn("Command returned both error and content.")
 		}
+		metrics.IncErrorCommand()
 		content = matrix.TextMessage{"m.notice", err.Error()}
+	} else {
+		metrics.IncSuccessCommand()
 	}
 
 	return content