Add Minecraft input plugin (#2960)

plugins/inputs/minecraft/rcon.go

@@ -0,0 +1,88 @@
+package minecraft
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/influxdata/telegraf/plugins/inputs/minecraft/internal/rcon"
+)
+
+const (
+	// NoMatches is a sentinel value returned when there are no statistics defined on the
+	//minecraft server
+	NoMatches = `All matches failed`
+	// ScoreboardPlayerList is the command to see all player statistics
+	ScoreboardPlayerList = `scoreboard players list *`
+)
+
+// RCONClient is a representation of RCON command authorizaiton and exectution
+type RCONClient interface {
+	Authorize(password string) (*rcon.Packet, error)
+	Execute(command string) (*rcon.Packet, error)
+}
+
+// RCON represents a RCON server connection
+type RCON struct {
+	Server   string
+	Port     string
+	Password string
+	client   RCONClient
+}
+
+// NewRCON creates a new RCON
+func NewRCON(server, port, password string) (*RCON, error) {
+	client, err := newClient(server, port)
+	if err != nil {
+		return nil, err
+	}
+
+	return &RCON{
+		Server:   server,
+		Port:     port,
+		Password: password,
+		client:   client,
+	}, nil
+}
+
+func newClient(server, port string) (*rcon.Client, error) {
+	p, err := strconv.Atoi(port)
+	if err != nil {
+		return nil, err
+	}
+
+	return rcon.NewClient(server, p)
+}
+
+// Gather recieves all player scoreboard information and returns it per player.
+func (r *RCON) Gather() ([]string, error) {
+	if r.client == nil {
+		var err error
+		r.client, err = newClient(r.Server, r.Port)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if _, err := r.client.Authorize(r.Password); err != nil {
+		// Potentially a network problem where the client will need to be
+		// re-initialized
+		r.client = nil
+		return nil, err
+	}
+
+	packet, err := r.client.Execute(ScoreboardPlayerList)
+	if err != nil {
+		// Potentially a network problem where the client will need to be
+		// re-initialized
+		r.client = nil
+		return nil, err
+	}
+
+	if !strings.Contains(packet.Body, NoMatches) {
+		players := strings.Split(packet.Body, "Showing")
+		if len(players) > 1 {
+			return players[1:], nil
+		}
+	}
+
+	return []string{}, nil
+}