plugin(mesos): Initial commit

The plugin is able to query a Mesos master and push the metrics, a
blacklist can be configured and a timeout, it's still not used.

Added unit test, might be a good idea to have system test using docker.

plugins/inputs/mesos/mesos_test.go

@@ -0,0 +1,119 @@
+package mesos
+
+import (
+	"encoding/json"
+	"math/rand"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+
+	"github.com/influxdata/telegraf/testutil"
+)
+
+var mesosMetrics map[string]interface{}
+var ts *httptest.Server
+
+func generateMetrics() {
+	mesosMetrics = make(map[string]interface{})
+
+	metricNames := []string{"master/cpus_percent", "master/cpus_used", "master/cpus_total",
+		"master/cpus_revocable_percent", "master/cpus_revocable_total", "master/cpus_revocable_used",
+		"master/disk_percent", "master/disk_used", "master/disk_total", "master/disk_revocable_percent",
+		"master/disk_revocable_total", "master/disk_revocable_used", "master/mem_percent",
+		"master/mem_used", "master/mem_total", "master/mem_revocable_percent", "master/mem_revocable_total",
+		"master/mem_revocable_used", "master/elected", "master/uptime_secs", "system/cpus_total",
+		"system/load_15min", "system/load_5min", "system/load_1min", "system/mem_free_bytes",
+		"system/mem_total_bytes", "master/slave_registrations", "master/slave_removals",
+		"master/slave_reregistrations", "master/slave_shutdowns_scheduled", "master/slave_shutdowns_canceled",
+		"master/slave_shutdowns_completed", "master/slaves_active", "master/slaves_connected",
+		"master/slaves_disconnected", "master/slaves_inactive", "master/frameworks_active",
+		"master/frameworks_connected", "master/frameworks_disconnected", "master/frameworks_inactive",
+		"master/outstanding_offers", "master/tasks_error", "master/tasks_failed", "master/tasks_finished",
+		"master/tasks_killed", "master/tasks_lost", "master/tasks_running", "master/tasks_staging",
+		"master/tasks_starting", "master/invalid_executor_to_framework_messages", "master/invalid_framework_to_executor_messages",
+		"master/invalid_status_update_acknowledgements", "master/invalid_status_updates",
+		"master/dropped_messages", "master/messages_authenticate", "master/messages_deactivate_framework",
+		"master/messages_decline_offers", "master/messages_executor_to_framework", "master/messages_exited_executor",
+		"master/messages_framework_to_executor", "master/messages_kill_task", "master/messages_launch_tasks",
+		"master/messages_reconcile_tasks", "master/messages_register_framework", "master/messages_register_slave",
+		"master/messages_reregister_framework", "master/messages_reregister_slave", "master/messages_resource_request",
+		"master/messages_revive_offers", "master/messages_status_update", "master/messages_status_update_acknowledgement",
+		"master/messages_unregister_framework", "master/messages_unregister_slave", "master/messages_update_slave",
+		"master/recovery_slave_removals", "master/slave_removals/reason_registered", "master/slave_removals/reason_unhealthy",
+		"master/slave_removals/reason_unregistered", "master/valid_framework_to_executor_messages", "master/valid_status_update_acknowledgements",
+		"master/valid_status_updates", "master/task_lost/source_master/reason_invalid_offers",
+		"master/task_lost/source_master/reason_slave_removed", "master/task_lost/source_slave/reason_executor_terminated",
+		"master/valid_executor_to_framework_messages", "master/event_queue_dispatches",
+		"master/event_queue_http_requests", "master/event_queue_messages", "registrar/state_fetch_ms",
+		"registrar/state_store_ms", "registrar/state_store_ms/max", "registrar/state_store_ms/min",
+		"registrar/state_store_ms/p50", "registrar/state_store_ms/p90", "registrar/state_store_ms/p95",
+		"registrar/state_store_ms/p99", "registrar/state_store_ms/p999", "registrar/state_store_ms/p9999"}
+
+	for _, k := range metricNames {
+		mesosMetrics[k] = rand.Float64()
+	}
+}
+
+func TestMain(m *testing.M) {
+	generateMetrics()
+	r := http.NewServeMux()
+	r.HandleFunc("/metrics/snapshot", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(mesosMetrics)
+	})
+	ts = httptest.NewServer(r)
+	rc := m.Run()
+	ts.Close()
+	os.Exit(rc)
+}
+
+func TestMesosMaster(t *testing.T) {
+	var acc testutil.Accumulator
+
+	m := Mesos{
+		Servers: []string{ts.Listener.Addr().String()},
+	}
+
+	err := m.Gather(&acc)
+
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+
+	acc.AssertContainsFields(t, "mesos", mesosMetrics)
+}
+
+func TestRemoveGroup(t *testing.T) {
+	j := []string{
+		"resources", "master",
+		"system", "slaves", "frameworks",
+		"tasks", "messages", "evqueue",
+		"messages", "registrar",
+	}
+
+	generateMetrics()
+
+	for _, v := range j {
+		m := Mesos{
+			Blacklist: []string{v},
+		}
+		err := m.removeGroup(&mesosMetrics)
+		if err != nil {
+			t.Errorf("Error removing non-exiting key: %s.", v)
+		}
+	}
+
+	if len(mesosMetrics) > 0 {
+		t.Error("Keys were left at slice sample")
+	}
+
+	m := Mesos{
+		Blacklist: []string{"fail"},
+	}
+
+	if err := m.removeGroup(&mesosMetrics); err == nil {
+		t.Errorf("Key %s should have returned error.", m.Blacklist[0])
+	}
+}