Add Prewarming Pool Alert

that checks for every environment if the filled share of the prewarmin pool is at least the specified threshold.

internal/api/health_test.go

@@ -1,16 +1,55 @@
 package api
 
 import (
+	"encoding/json"
+	"github.com/openHPI/poseidon/internal/config"
+	"github.com/openHPI/poseidon/internal/environment"
+	"github.com/openHPI/poseidon/pkg/dto"
+	"github.com/openHPI/poseidon/tests"
+	"io"
 	"net/http"
 	"net/http/httptest"
 )
 
-func (s *MainTestSuite) TestHealthRoute() {
-	request, err := http.NewRequest(http.MethodGet, "/health", http.NoBody)
-	if err != nil {
-		s.T().Fatal(err)
-	}
-	recorder := httptest.NewRecorder()
-	http.HandlerFunc(Health).ServeHTTP(recorder, request)
-	s.Equal(http.StatusNoContent, recorder.Code)
+func (s *MainTestSuite) TestHealth() {
+	s.Run("returns StatusNoContent as default", func() {
+		request, err := http.NewRequest(http.MethodGet, "/health", http.NoBody)
+		if err != nil {
+			s.T().Fatal(err)
+		}
+		recorder := httptest.NewRecorder()
+		manager := &environment.ManagerHandlerMock{}
+		manager.On("Statistics").Return(map[dto.EnvironmentID]*dto.StatisticalExecutionEnvironmentData{})
+
+		Health(manager).ServeHTTP(recorder, request)
+		s.Equal(http.StatusNoContent, recorder.Code)
+	})
+	s.Run("returns InternalServerError for warnings and errors", func() {
+		s.Run("Prewarming Pool Alert", func() {
+			request, err := http.NewRequest(http.MethodGet, "/health", http.NoBody)
+			if err != nil {
+				s.T().Fatal(err)
+			}
+			recorder := httptest.NewRecorder()
+			manager := &environment.ManagerHandlerMock{}
+			manager.On("Statistics").Return(map[dto.EnvironmentID]*dto.StatisticalExecutionEnvironmentData{
+				tests.DefaultEnvironmentIDAsInteger: {
+					ID:                 tests.DefaultEnvironmentIDAsInteger,
+					PrewarmingPoolSize: 3,
+					IdleRunners:        1,
+				},
+			})
+			config.Config.Server.PrewarmingPoolAlertThreshold = 0.5
+
+			Health(manager).ServeHTTP(recorder, request)
+			s.Equal(http.StatusServiceUnavailable, recorder.Code)
+
+			b, err := io.ReadAll(recorder.Body)
+			s.Require().NoError(err)
+			var details dto.InternalServerError
+			err = json.Unmarshal(b, &details)
+			s.Require().NoError(err)
+			s.Contains(details.Message, ErrorPrewarmingPoolDepleting.Error())
+		})
+	})
 }