Fix flaky e2e tests because of no idle runners

at startup.

tests/e2e/e2e_test.go

@@ -94,6 +94,7 @@ func initNomad() {
 		return
 	}
 	createDefaultEnvironment()
+	waitForDefaultEnvironment()
 }
 
 func createDefaultEnvironment() {
@@ -123,6 +124,28 @@ func createDefaultEnvironment() {
 	}
 }
 
+func waitForDefaultEnvironment() {
+	path := helpers.BuildURL(api.BasePath, api.RunnersPath)
+	body := &dto.RunnerRequest{
+		ExecutionEnvironmentID: tests.DefaultEnvironmentIDAsInteger,
+		InactivityTimeout:      1,
+	}
+	var code int
+	const maxRetries = 60
+	for count := 0; count < maxRetries && code != http.StatusOK; count++ {
+		<-time.After(time.Second)
+		if resp, err := helpers.HTTPPostJSON(path, body); err == nil {
+			code = resp.StatusCode
+			log.WithField("count", count).WithField("statusCode", code).Info("Waiting for idle runners")
+		} else {
+			log.WithField("count", count).WithError(err).Warn("Waiting for idle runners")
+		}
+	}
+	if code != http.StatusOK {
+		log.Fatal("Failed to provide a runner")
+	}
+}
+
 func deleteE2EEnvironments() {
 	for _, id := range environmentIDs {
 		deleteEnvironment(&testing.T{}, id.ToString())

tests/helpers/test_helpers.go

@@ -180,6 +180,26 @@ func HTTPPutJSON(url string, body interface{}) (response *http.Response, err err
 	return HTTPPut(url, reader)
 }
 
+func HTTPPostJSON(url string, body interface{}) (response *http.Response, err error) {
+	requestByteString, err := json.Marshal(body)
+	if err != nil {
+		return nil, fmt.Errorf("cannot marshal passed http post body: %w", err)
+	}
+	bodyReader := bytes.NewReader(requestByteString)
+
+	//nolint:noctx // we don't need a http.NewRequestWithContext in our tests
+	req, err := httpRequest(http.MethodPost, url, bodyReader)
+	if err != nil {
+		return nil, err
+	}
+	client := &http.Client{}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("error executing request: %w", err)
+	}
+	return resp, nil
+}
+
 const templateJobPriority = 100
 
 func CreateTemplateJob() (base, job *nomadApi.Job) {