Prometheus: Migrate metadata queries to use resource calls (#49921)

* Sent resource calls for metadata to the backend * moved resource calls to the backend * code review feedback * fixed post with body * statuscode >= 300 * cleanup * fixed tests * fixed datasource tests * code review feedback * force some other endpoints to only GET * fix linting errors * fixed tests * was able to remove section of redundant code * cleanup and code review feedback * moved query_exemplars to get request * fixed return on error * went back to resource calls, but using the backendsrv directly * moved to a resource call with fallback * fixed tests * check for proper messages * proper check for invalid calls * code review changes
2022-06-03 15:56:13 -03:00
parent d2f3631a47
commit 53ee72d15d
6 changed files with 181 additions and 28 deletions
@@ -0,0 +1,85 @@
+package resource
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/url"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana/pkg/infra/httpclient"
+	"github.com/grafana/grafana/pkg/infra/log"
+	"github.com/grafana/grafana/pkg/services/featuremgmt"
+	"github.com/grafana/grafana/pkg/setting"
+	"github.com/grafana/grafana/pkg/tsdb/prometheus/client"
+)
+
+type Resource struct {
+	provider *client.Provider
+	log      log.Logger
+}
+
+func New(
+	httpClientProvider httpclient.Provider,
+	cfg *setting.Cfg,
+	features featuremgmt.FeatureToggles,
+	settings backend.DataSourceInstanceSettings,
+	plog log.Logger,
+) (*Resource, error) {
+	var jsonData map[string]interface{}
+	if err := json.Unmarshal(settings.JSONData, &jsonData); err != nil {
+		return nil, fmt.Errorf("error reading settings: %w", err)
+	}
+
+	p := client.NewProvider(settings, jsonData, httpClientProvider, cfg, features, plog)
+
+	return &Resource{
+		log:      plog,
+		provider: p,
+	}, nil
+}
+
+func (r *Resource) Execute(ctx context.Context, req *backend.CallResourceRequest) (int, []byte, error) {
+	client, err := r.provider.GetClient(reqHeaders(req.Headers))
+	if err != nil {
+		return 500, nil, err
+	}
+
+	return r.fetch(ctx, client, req)
+}
+
+func (r *Resource) fetch(ctx context.Context, client *client.Client, req *backend.CallResourceRequest) (int, []byte, error) {
+	r.log.Debug("Sending resource query", "URL", req.URL)
+	u, err := url.Parse(req.URL)
+	if err != nil {
+		return 500, nil, err
+	}
+
+	resp, err := client.QueryResource(ctx, req.Method, u.Path, u.Query())
+	if err != nil {
+		return resp.StatusCode, nil, err
+	}
+
+	defer resp.Body.Close() //nolint (we don't care about the error being returned by resp.Body.Close())
+
+	data, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return 500, nil, err
+	}
+
+	return resp.StatusCode, data, err
+}
+
+func reqHeaders(headers map[string][]string) map[string]string {
+	// Keep only the authorization header, incase downstream the authorization header is required.
+	// Strip all the others out as appropriate headers will be applied to speak with prometheus.
+	h := make(map[string]string)
+	accessValues := headers["Authorization"]
+
+	if len(accessValues) > 0 {
+		h["Authorization"] = accessValues[0]
+	}
+
+	return h
+}