Add e2e tests for exec env createOrUpdate

This also adds a Nomad client to the e2e_tests that can be used to
query Nomad and validate that certain actions happened in Nomad
correctly.

tests/e2e/e2e_test.go

@@ -1,6 +1,7 @@
 package e2e
 
 import (
+	nomadApi "github.com/hashicorp/nomad/api"
 	"github.com/stretchr/testify/suite"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/config"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/logging"
@@ -15,7 +16,11 @@ import (
 * For the e2e tests a nomad cluster must be connected and poseidon must be running.
  */
 
-var log = logging.GetLogger("e2e")
+var (
+	log            = logging.GetLogger("e2e")
+	nomadClient    *nomadApi.Client
+	nomadNamespace string
+)
 
 type E2ETestSuite struct {
 	suite.Suite
@@ -35,7 +40,16 @@ func TestMain(m *testing.M) {
 	log.Info("Test Setup")
 	err := config.InitConfig()
 	if err != nil {
-		log.Warn("Could not initialize configuration")
+		log.WithError(err).Fatal("Could not initialize configuration")
+	}
+	nomadNamespace = config.Config.Nomad.Namespace
+	nomadClient, err = nomadApi.NewClient(&nomadApi.Config{
+		Address:   config.Config.NomadAPIURL().String(),
+		TLSConfig: &nomadApi.TLSConfig{},
+		Namespace: nomadNamespace,
+	})
+	if err != nil {
+		log.WithError(err).Fatal("Could not create Nomad client")
 	}
 	// ToDo: Add Nomad job here when it is possible to create execution environments. See #26.
 	log.Info("Test Run")