Elasticsearch: Implement CheckHealth method in the backend (#81671)

* Elasticsearch: Implement CheckHealth method

* improve logger output

* remove frontend healthcheck

* Revert "remove frontend healthcheck"

This reverts commit 676265f39e.

* adapt test

---------

Co-authored-by: Sven Grossmann <svennergr@gmail.com>

pkg/tsdb/elasticsearch/healthcheck.go

@@ -0,0 +1,107 @@
+package elasticsearch
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/url"
+	"path"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+)
+
+func (s *Service) CheckHealth(ctx context.Context, req *backend.CheckHealthRequest) (*backend.CheckHealthResult, error) {
+	logger := eslog.FromContext(ctx)
+
+	ds, err := s.getDSInfo(ctx, req.PluginContext)
+	if err != nil {
+		logger.Error("Failed to get data source info", "error", err)
+		return &backend.CheckHealthResult{
+			Status:  backend.HealthStatusUnknown,
+			Message: "Failed to get data source info",
+		}, err
+	}
+
+	esUrl, err := url.Parse(ds.URL)
+	if err != nil {
+		logger.Error("Failed to parse data source URL", "error", err, "url", ds.URL)
+		return &backend.CheckHealthResult{
+			Status:  backend.HealthStatusUnknown,
+			Message: "Failed to parse data source URL",
+		}, err
+	}
+
+	esUrl.Path = path.Join(esUrl.Path, "_cluster/health")
+	esUrl.RawQuery = "wait_for_status=yellow"
+
+	request, err := http.NewRequestWithContext(ctx, "GET", esUrl.String(), nil)
+	if err != nil {
+		logger.Error("Failed to create request", "error", err, "url", esUrl.String())
+		return &backend.CheckHealthResult{
+			Status:  backend.HealthStatusUnknown,
+			Message: "Failed to create request",
+		}, err
+	}
+
+	start := time.Now()
+	logger.Debug("Sending healthcheck request to Elasticsearch", "url", esUrl.String())
+	response, err := ds.HTTPClient.Do(request)
+
+	if err != nil {
+		logger.Error("Failed to do healthcheck request", "error", err, "url", esUrl.String())
+		return &backend.CheckHealthResult{
+			Status:  backend.HealthStatusUnknown,
+			Message: "Failed to do healthcheck request",
+		}, err
+	}
+
+	if response.StatusCode == http.StatusRequestTimeout {
+		return &backend.CheckHealthResult{
+			Status:  backend.HealthStatusError,
+			Message: "Elasticsearch data source is not healthy",
+		}, nil
+	}
+
+	logger.Info("Response received from Elasticsearch", "statusCode", response.StatusCode, "status", "ok", "duration", time.Since(start))
+
+	defer func() {
+		if err := response.Body.Close(); err != nil {
+			logger.Warn("Failed to close response body", "error", err)
+		}
+	}()
+
+	body, err := io.ReadAll(response.Body)
+	if err != nil {
+		logger.Error("Error reading response body bytes", "error", err)
+		return &backend.CheckHealthResult{
+			Status:  backend.HealthStatusUnknown,
+			Message: "Failed to read response",
+		}, err
+	}
+
+	jsonData := map[string]any{}
+
+	err = json.Unmarshal(body, &jsonData)
+	if err != nil {
+		logger.Error("Error during json unmarshal of the body", "error", err)
+		return &backend.CheckHealthResult{
+			Status:  backend.HealthStatusUnknown,
+			Message: "Failed to unmarshal response",
+		}, err
+	}
+
+	status := backend.HealthStatusOk
+	message := "Elasticsearch data source is healthy"
+
+	if jsonData["status"] == "red" {
+		status = backend.HealthStatusError
+		message = "Elasticsearch data source is not healthy"
+	}
+
+	return &backend.CheckHealthResult{
+		Status:  status,
+		Message: message,
+	}, nil
+}

pkg/tsdb/elasticsearch/healthcheck_test.go

@@ -0,0 +1,80 @@
+package elasticsearch
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"net/http"
+	"testing"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	sdkhttpclient "github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
+	"github.com/grafana/grafana-plugin-sdk-go/backend/instancemgmt"
+	es "github.com/grafana/grafana/pkg/tsdb/elasticsearch/client"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_Healthcheck_OK(t *testing.T) {
+	service := GetMockService(true)
+	res, _ := service.CheckHealth(context.Background(), &backend.CheckHealthRequest{
+		PluginContext: backend.PluginContext{},
+		Headers:       nil,
+	})
+	assert.Equal(t, backend.HealthStatusOk, res.Status)
+	assert.Equal(t, "Elasticsearch data source is healthy", res.Message)
+}
+
+func Test_Healthcheck_Timeout(t *testing.T) {
+	service := GetMockService(false)
+	res, _ := service.CheckHealth(context.Background(), &backend.CheckHealthRequest{
+		PluginContext: backend.PluginContext{},
+		Headers:       nil,
+	})
+	assert.Equal(t, backend.HealthStatusError, res.Status)
+	assert.Equal(t, "Elasticsearch data source is not healthy", res.Message)
+}
+
+type FakeRoundTripper struct {
+	isDsHealthy bool
+}
+
+func (fakeRoundTripper *FakeRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	var res *http.Response
+	if fakeRoundTripper.isDsHealthy {
+		res = &http.Response{
+			StatusCode: http.StatusOK,
+			Status:     "200 OK",
+			Body:       io.NopCloser(bytes.NewBufferString("{\"status\":\"green\"}")),
+		}
+	} else {
+		res = &http.Response{
+			StatusCode: http.StatusRequestTimeout,
+			Status:     "408 Request Timeout",
+			Body:       io.NopCloser(bytes.NewBufferString("{\"status\":\"red\"}")),
+		}
+	}
+	return res, nil
+}
+
+type FakeInstanceManager struct {
+	isDsHealthy bool
+}
+
+func (fakeInstanceManager *FakeInstanceManager) Get(tx context.Context, pluginContext backend.PluginContext) (instancemgmt.Instance, error) {
+	httpClient, _ := sdkhttpclient.New(sdkhttpclient.Options{})
+	httpClient.Transport = &FakeRoundTripper{isDsHealthy: fakeInstanceManager.isDsHealthy}
+
+	return es.DatasourceInfo{
+		HTTPClient: httpClient,
+	}, nil
+}
+
+func (*FakeInstanceManager) Do(_ context.Context, _ backend.PluginContext, _ instancemgmt.InstanceCallbackFunc) error {
+	return nil
+}
+
+func GetMockService(isDsHealthy bool) *Service {
+	return &Service{
+		im: &FakeInstanceManager{isDsHealthy: isDsHealthy},
+	}
+}