Forward oauth tokens after prometheus datasource migration (#43686) (#43818)

* create the prom client

* implement lru cache of prometheus clients based on auth headers

* linter

(cherry picked from commit 20b3b2a448)

pkg/tsdb/prometheus/middleware/custom_query_params.go

@@ -1,4 +1,4 @@
-package prometheus
+package middleware
 
 import (
 	"net/http"
@@ -14,7 +14,7 @@ const (
 	grafanaDataKey                      = "grafanaData"
 )
 
-func customQueryParametersMiddleware(logger log.Logger) sdkhttpclient.Middleware {
+func CustomQueryParameters(logger log.Logger) sdkhttpclient.Middleware {
 	return sdkhttpclient.NamedMiddlewareFunc(customQueryParametersMiddlewareName, func(opts sdkhttpclient.Options, next http.RoundTripper) http.RoundTripper {
 		grafanaData, exists := opts.CustomOptions[grafanaDataKey]
 		if !exists {

pkg/tsdb/prometheus/middleware/custom_query_params_test.go

@@ -1,4 +1,4 @@
-package prometheus
+package middleware
 
 import (
 	"net/http"
@@ -19,7 +19,7 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 	})
 
 	t.Run("Without custom query parameters set should not apply middleware", func(t *testing.T) {
-		mw := customQueryParametersMiddleware(log.New("test"))
+		mw := CustomQueryParameters(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{}, finalRoundTripper)
 		require.NotNil(t, rt)
 		middlewareName, ok := mw.(httpclient.MiddlewareName)
@@ -39,7 +39,7 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 	})
 
 	t.Run("Without custom query parameters set as string should not apply middleware", func(t *testing.T) {
-		mw := customQueryParametersMiddleware(log.New("test"))
+		mw := CustomQueryParameters(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{
 			CustomOptions: map[string]interface{}{
 				customQueryParametersKey: 64,
@@ -63,7 +63,7 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 	})
 
 	t.Run("With custom query parameters set as empty string should not apply middleware", func(t *testing.T) {
-		mw := customQueryParametersMiddleware(log.New("test"))
+		mw := CustomQueryParameters(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{
 			CustomOptions: map[string]interface{}{
 				customQueryParametersKey: "",
@@ -87,7 +87,7 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 	})
 
 	t.Run("With custom query parameters set as invalid query string should not apply middleware", func(t *testing.T) {
-		mw := customQueryParametersMiddleware(log.New("test"))
+		mw := CustomQueryParameters(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{
 			CustomOptions: map[string]interface{}{
 				customQueryParametersKey: "custom=%%abc&test=abc",
@@ -111,7 +111,7 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 	})
 
 	t.Run("With custom query parameters set should apply middleware for request URL containing query parameters ", func(t *testing.T) {
-		mw := customQueryParametersMiddleware(log.New("test"))
+		mw := CustomQueryParameters(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{
 			CustomOptions: map[string]interface{}{
 				grafanaDataKey: map[string]interface{}{
@@ -143,7 +143,7 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 	})
 
 	t.Run("With custom query parameters set should apply middleware for request URL not containing query parameters", func(t *testing.T) {
-		mw := customQueryParametersMiddleware(log.New("test"))
+		mw := CustomQueryParameters(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{
 			CustomOptions: map[string]interface{}{
 				grafanaDataKey: map[string]interface{}{

pkg/tsdb/prometheus/middleware/force_http_get.go

@@ -1,4 +1,4 @@
-package prometheus
+package middleware
 
 import (
 	"net/http"
@@ -7,13 +7,14 @@ import (
 	"github.com/grafana/grafana/pkg/infra/log"
 )
 
-func forceHttpGetMiddleware(logger log.Logger) sdkhttpclient.Middleware {
+func ForceHttpGet(logger log.Logger) sdkhttpclient.Middleware {
 	return sdkhttpclient.NamedMiddlewareFunc("force-http-get", func(opts sdkhttpclient.Options, next http.RoundTripper) http.RoundTripper {
 		// the prometheus library we use does not allow us to set the http method.
 		// it's behavior is to first try POST, and if it fails in certain ways
 		// (for example, by returning a method-not-allowed error), it will try GET.
 		// so here, we check if the http-method is POST, and if it is, we
 		// return an artificial method-not-allowed response.
+
 		// this will cause the prometheus library to retry with GET.
 		return sdkhttpclient.RoundTripperFunc(func(req *http.Request) (*http.Response, error) {
 			if req.Method == http.MethodPost {

pkg/tsdb/prometheus/middleware/force_http_get_test.go

@@ -1,4 +1,4 @@
-package prometheus
+package middleware
 
 import (
 	"net/http"
@@ -9,52 +9,12 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestForceGet(t *testing.T) {
-	t.Run("With nil jsonOpts, should not force get-method", func(t *testing.T) {
-		var jsonOpts map[string]interface{}
-		require.False(t, forceHttpGet(jsonOpts))
-	})
-
-	t.Run("With empty jsonOpts, should not force get-method", func(t *testing.T) {
-		jsonOpts := make(map[string]interface{})
-		require.False(t, forceHttpGet(jsonOpts))
-	})
-
-	t.Run("With httpMethod=nil, should not not force get-method", func(t *testing.T) {
-		jsonOpts := map[string]interface{}{
-			"httpMethod": nil,
-		}
-		require.False(t, forceHttpGet(jsonOpts))
-	})
-
-	t.Run("With httpMethod=post, should not force get-method", func(t *testing.T) {
-		jsonOpts := map[string]interface{}{
-			"httpMethod": "POST",
-		}
-		require.False(t, forceHttpGet(jsonOpts))
-	})
-
-	t.Run("With httpMethod=get, should force get-method", func(t *testing.T) {
-		jsonOpts := map[string]interface{}{
-			"httpMethod": "get",
-		}
-		require.True(t, forceHttpGet(jsonOpts))
-	})
-
-	t.Run("With httpMethod=GET, should force get-method", func(t *testing.T) {
-		jsonOpts := map[string]interface{}{
-			"httpMethod": "GET",
-		}
-		require.True(t, forceHttpGet(jsonOpts))
-	})
-}
-
 func TestEnsureHttpMethodMiddleware(t *testing.T) {
 	t.Run("Name should be correct", func(t *testing.T) {
 		finalRoundTripper := httpclient.RoundTripperFunc(func(req *http.Request) (*http.Response, error) {
 			return &http.Response{StatusCode: http.StatusOK}, nil
 		})
-		mw := forceHttpGetMiddleware(log.New("test"))
+		mw := ForceHttpGet(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{}, finalRoundTripper)
 		require.NotNil(t, rt)
 		middlewareName, ok := mw.(httpclient.MiddlewareName)
@@ -67,7 +27,7 @@ func TestEnsureHttpMethodMiddleware(t *testing.T) {
 			return &http.Response{StatusCode: http.StatusOK}, nil
 		})
 
-		mw := forceHttpGetMiddleware(log.New("test"))
+		mw := ForceHttpGet(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{}, finalRoundTripper)
 		require.NotNil(t, rt)
 

pkg/tsdb/prometheus/promclient/cache.go

@@ -0,0 +1,55 @@
+package promclient
+
+import (
+	lru "github.com/hashicorp/golang-lru"
+	apiv1 "github.com/prometheus/client_golang/api/prometheus/v1"
+)
+
+const (
+	noPassThrough = "no-pass-through"
+)
+
+type ProviderCache struct {
+	provider promClientProvider
+	cache    *lru.Cache
+	jsonData JsonData
+}
+
+type promClientProvider interface {
+	GetClient(map[string]string) (apiv1.API, error)
+}
+
+func NewProviderCache(p promClientProvider, jd JsonData) (*ProviderCache, error) {
+	cache, err := lru.New(500)
+	if err != nil {
+		return nil, err
+	}
+
+	return &ProviderCache{
+		provider: p,
+		cache:    cache,
+		jsonData: jd,
+	}, nil
+}
+
+func (c *ProviderCache) GetClient(headers map[string]string) (apiv1.API, error) {
+	key := c.key(headers)
+	if client, ok := c.cache.Get(key); ok {
+		return client.(apiv1.API), nil
+	}
+
+	client, err := c.provider.GetClient(headers)
+	if err != nil {
+		return nil, err
+	}
+
+	c.cache.Add(key, client)
+	return client, nil
+}
+
+func (c *ProviderCache) key(headers map[string]string) string {
+	if c.jsonData.OauthPassThru {
+		return headers[authHeader] + headers[idTokenHeader]
+	}
+	return noPassThrough
+}

pkg/tsdb/prometheus/promclient/cache_test.go

@@ -0,0 +1,144 @@
+package promclient_test
+
+import (
+	"context"
+	"errors"
+	"sort"
+	"strings"
+	"testing"
+
+	"github.com/grafana/grafana/pkg/tsdb/prometheus/promclient"
+
+	apiv1 "github.com/prometheus/client_golang/api/prometheus/v1"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCache_GetClient(t *testing.T) {
+	t.Run("it caches the client for a set of auth headers", func(t *testing.T) {
+		tc := setupCacheContext(true)
+
+		c, err := tc.providerCache.GetClient(headers)
+		require.Nil(t, err)
+
+		c2, err := tc.providerCache.GetClient(headers)
+		require.Nil(t, err)
+
+		require.Equal(t, c, c2)
+		require.Equal(t, 1, tc.clientProvider.numCalls)
+	})
+
+	t.Run("it returns different clients when the auth headers differ", func(t *testing.T) {
+		tc := setupCacheContext(true)
+		h1 := map[string]string{"Authorization": "token", "X-ID-Token": "id-token"}
+		h2 := map[string]string{"Authorization": "token2", "X-ID-Token": "id-token"}
+
+		c, err := tc.providerCache.GetClient(h1)
+		require.Nil(t, err)
+
+		c2, err := tc.providerCache.GetClient(h2)
+		require.Nil(t, err)
+
+		require.NotEqual(t, c, c2)
+		require.Equal(t, 2, tc.clientProvider.numCalls)
+	})
+
+	t.Run("it always returns from the cache when 'oauthPassThru' not set", func(t *testing.T) {
+		tc := setupCacheContext(false)
+		h1 := map[string]string{"Authorization": "token", "X-ID-Token": "id-token"}
+		h2 := map[string]string{"Authorization": "token2", "X-ID-Token": "id-token"}
+
+		c, err := tc.providerCache.GetClient(h1)
+		require.Nil(t, err)
+
+		c2, err := tc.providerCache.GetClient(h2)
+		require.Nil(t, err)
+
+		require.Equal(t, c, c2)
+		require.Equal(t, 1, tc.clientProvider.numCalls)
+	})
+
+	t.Run("it only accounts for auth headers", func(t *testing.T) {
+		tc := setupCacheContext(true)
+
+		c, err := tc.providerCache.GetClient(map[string]string{"X-Not-Auth": "stuff"})
+		require.Nil(t, err)
+
+		c2, err := tc.providerCache.GetClient(map[string]string{"X-Not-Auth": "other-stuff"})
+		require.Nil(t, err)
+
+		require.Equal(t, c, c2)
+		require.Equal(t, 1, tc.clientProvider.numCalls)
+	})
+
+	t.Run("it doesn't cache anything when an error occurs", func(t *testing.T) {
+		tc := setupCacheContext(true)
+		tc.clientProvider.errors <- errors.New("something bad")
+
+		_, err := tc.providerCache.GetClient(headers)
+		require.EqualError(t, err, "something bad")
+
+		c, err := tc.providerCache.GetClient(headers)
+		require.Nil(t, err)
+
+		require.NotNil(t, c)
+		require.Equal(t, 2, tc.clientProvider.numCalls)
+	})
+}
+
+type cacheTestContext struct {
+	providerCache  *promclient.ProviderCache
+	clientProvider *fakePromClientProvider
+}
+
+func setupCacheContext(oauthPassTrough bool) *cacheTestContext {
+	fp := newFakePromClientProvider()
+	p, err := promclient.NewProviderCache(fp, promclient.JsonData{OauthPassThru: oauthPassTrough})
+	if err != nil {
+		panic(err)
+	}
+
+	return &cacheTestContext{
+		providerCache:  p,
+		clientProvider: fp,
+	}
+}
+
+func newFakePromClientProvider() *fakePromClientProvider {
+	return &fakePromClientProvider{
+		errors: make(chan error, 1),
+	}
+}
+
+type fakePromClientProvider struct {
+	headers  map[string]string
+	numCalls int
+	errors   chan error
+}
+
+func (p *fakePromClientProvider) GetClient(h map[string]string) (apiv1.API, error) {
+	p.headers = h
+	p.numCalls++
+
+	var err error
+	select {
+	case err = <-p.errors:
+	default:
+	}
+
+	var config []string
+	for _, v := range h {
+		config = append(config, v)
+	}
+	sort.Strings(config) //because map
+	return &fakePromClient{config: strings.Join(config, "")}, err
+}
+
+type fakePromClient struct {
+	apiv1.API
+	config string
+}
+
+func (c *fakePromClient) Config(ctx context.Context) (apiv1.ConfigResult, error) {
+	return apiv1.ConfigResult{YAML: c.config}, nil
+}

pkg/tsdb/prometheus/promclient/provider.go

@@ -0,0 +1,106 @@
+package promclient
+
+import (
+	"strings"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+
+	"github.com/grafana/grafana/pkg/tsdb/prometheus/middleware"
+
+	sdkhttpclient "github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
+	"github.com/grafana/grafana/pkg/infra/httpclient"
+	"github.com/grafana/grafana/pkg/infra/log"
+	"github.com/prometheus/client_golang/api"
+	apiv1 "github.com/prometheus/client_golang/api/prometheus/v1"
+)
+
+const (
+	authHeader    = "Authorization"
+	idTokenHeader = "X-ID-Token"
+)
+
+type Provider struct {
+	settings       backend.DataSourceInstanceSettings
+	jsonData       JsonData
+	clientProvider httpclient.Provider
+	log            log.Logger
+}
+
+func NewProvider(
+	settings backend.DataSourceInstanceSettings,
+	jsonData JsonData,
+	clientProvider httpclient.Provider,
+	log log.Logger,
+) *Provider {
+	return &Provider{
+		settings:       settings,
+		jsonData:       jsonData,
+		clientProvider: clientProvider,
+		log:            log,
+	}
+}
+
+type JsonData struct {
+	Method        string `json:"httpMethod"`
+	OauthPassThru bool   `json:"oauthPassThru"`
+	TimeInterval  string `json:"timeInterval"`
+}
+
+func (p *Provider) GetClient(headers map[string]string) (apiv1.API, error) {
+	opts, err := p.settings.HTTPClientOptions()
+	if err != nil {
+		return nil, err
+	}
+
+	opts.Middlewares = p.middlewares()
+	if p.jsonData.OauthPassThru {
+		opts.Headers = authHeaders(headers)
+	}
+
+	// Set SigV4 service namespace
+	if opts.SigV4 != nil {
+		opts.SigV4.Service = "aps"
+	}
+
+	roundTripper, err := p.clientProvider.GetTransport(opts)
+	if err != nil {
+		return nil, err
+	}
+
+	cfg := api.Config{
+		Address:      p.settings.URL,
+		RoundTripper: roundTripper,
+	}
+
+	client, err := api.NewClient(cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	return apiv1.NewAPI(client), nil
+}
+
+func (p *Provider) middlewares() []sdkhttpclient.Middleware {
+	middlewares := []sdkhttpclient.Middleware{
+		middleware.CustomQueryParameters(p.log),
+		sdkhttpclient.CustomHeadersMiddleware(),
+	}
+	if strings.ToLower(p.jsonData.Method) == "get" {
+		middlewares = append(middlewares, middleware.ForceHttpGet(p.log))
+	}
+
+	return middlewares
+}
+
+func authHeaders(headers map[string]string) map[string]string {
+	authHeaders := make(map[string]string)
+	if v, ok := headers[authHeader]; ok {
+		authHeaders[authHeader] = v
+	}
+
+	if v, ok := headers[idTokenHeader]; ok {
+		authHeaders[idTokenHeader] = v
+	}
+
+	return authHeaders
+}

pkg/tsdb/prometheus/promclient/provider_test.go

@@ -0,0 +1,186 @@
+package promclient_test
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/grafana/grafana/pkg/tsdb/prometheus/promclient"
+
+	"github.com/grafana/grafana/pkg/setting"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+
+	sdkhttpclient "github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
+	"github.com/grafana/grafana/pkg/infra/httpclient"
+
+	"github.com/stretchr/testify/require"
+)
+
+var headers = map[string]string{"Authorization": "token", "X-ID-Token": "id-token"}
+
+func TestGetClient(t *testing.T) {
+	t.Run("it sets the SigV4 service if it exists", func(t *testing.T) {
+		tc := setup(`{"sigV4Auth":true}`)
+
+		setting.SigV4AuthEnabled = true
+		defer func() { setting.SigV4AuthEnabled = false }()
+
+		_, err := tc.promClientProvider.GetClient(headers)
+		require.Nil(t, err)
+
+		require.Equal(t, "aps", tc.httpProvider.opts.SigV4.Service)
+	})
+
+	t.Run("it always uses the custom params and custom headers middlewares", func(t *testing.T) {
+		tc := setup()
+
+		_, err := tc.promClientProvider.GetClient(headers)
+		require.Nil(t, err)
+
+		require.Len(t, tc.httpProvider.middlewares(), 2)
+		require.Contains(t, tc.httpProvider.middlewares(), "prom-custom-query-parameters")
+		require.Contains(t, tc.httpProvider.middlewares(), "CustomHeaders")
+	})
+
+	t.Run("oauth pass through", func(t *testing.T) {
+		t.Run("it sets the headers when 'oauthPassThru' is true and auth headers are passed", func(t *testing.T) {
+			tc := setup(`{"oauthPassThru":true}`)
+			_, err := tc.promClientProvider.GetClient(headers)
+			require.Nil(t, err)
+
+			require.Equal(t, headers, tc.httpProvider.opts.Headers)
+		})
+
+		t.Run("it only sets auth headers", func(t *testing.T) {
+			withNonAuth := map[string]string{"X-Not-Auth": "stuff"}
+
+			tc := setup(`{"oauthPassThru":true}`)
+			_, err := tc.promClientProvider.GetClient(withNonAuth)
+			require.Nil(t, err)
+
+			require.Equal(t, map[string]string{}, tc.httpProvider.opts.Headers)
+		})
+
+		t.Run("it does not error when headers are nil", func(t *testing.T) {
+			tc := setup(`{"oauthPassThru":true}`)
+
+			_, err := tc.promClientProvider.GetClient(nil)
+			require.Nil(t, err)
+		})
+
+		t.Run("it does not set the headers when 'oauthPassThru' is false", func(t *testing.T) {
+			tc := setup()
+			_, err := tc.promClientProvider.GetClient(headers)
+			require.Nil(t, err)
+
+			require.Len(t, tc.httpProvider.opts.Headers, 0)
+		})
+	})
+
+	t.Run("force get middleware", func(t *testing.T) {
+		t.Run("it add the force-get middleware when httpMethod is get", func(t *testing.T) {
+			tc := setup(`{"httpMethod":"get"}`)
+
+			_, err := tc.promClientProvider.GetClient(headers)
+			require.Nil(t, err)
+
+			require.Len(t, tc.httpProvider.middlewares(), 3)
+			require.Contains(t, tc.httpProvider.middlewares(), "force-http-get")
+		})
+
+		t.Run("it add the force-get middleware when httpMethod is get", func(t *testing.T) {
+			tc := setup(`{"httpMethod":"GET"}`)
+
+			_, err := tc.promClientProvider.GetClient(headers)
+			require.Nil(t, err)
+
+			require.Len(t, tc.httpProvider.middlewares(), 3)
+			require.Contains(t, tc.httpProvider.middlewares(), "force-http-get")
+		})
+
+		t.Run("it does not add the force-get middleware when httpMethod is POST", func(t *testing.T) {
+			tc := setup(`{"httpMethod":"POST"}`)
+
+			_, err := tc.promClientProvider.GetClient(headers)
+			require.Nil(t, err)
+
+			require.NotContains(t, tc.httpProvider.middlewares(), "force-http-get")
+		})
+
+		t.Run("it does not add the force-get middleware when json data is nil", func(t *testing.T) {
+			tc := setup()
+
+			_, err := tc.promClientProvider.GetClient(headers)
+			require.Nil(t, err)
+
+			require.NotContains(t, tc.httpProvider.middlewares(), "force-http-get")
+		})
+
+		t.Run("it does not add the force-get middleware when json data is empty", func(t *testing.T) {
+			tc := setup(`{}`)
+
+			_, err := tc.promClientProvider.GetClient(headers)
+			require.Nil(t, err)
+
+			require.NotContains(t, tc.httpProvider.middlewares(), "force-http-get")
+		})
+
+		t.Run("it does not add the force-get middleware httpMethod is null", func(t *testing.T) {
+			tc := setup(`{"httpMethod":null}`)
+
+			_, err := tc.promClientProvider.GetClient(headers)
+			require.Nil(t, err)
+
+			require.NotContains(t, tc.httpProvider.middlewares(), "force-http-get")
+		})
+	})
+}
+
+func setup(jsonData ...string) *testContext {
+	var rawData []byte
+	if len(jsonData) > 0 {
+		rawData = []byte(jsonData[0])
+	}
+
+	var jd promclient.JsonData
+	_ = json.Unmarshal(rawData, &jd)
+
+	settings := backend.DataSourceInstanceSettings{URL: "test-url", JSONData: rawData}
+	hp := &fakeHttpClientProvider{}
+	p := promclient.NewProvider(settings, jd, hp, nil)
+
+	return &testContext{
+		httpProvider:       hp,
+		promClientProvider: p,
+	}
+}
+
+type testContext struct {
+	httpProvider       *fakeHttpClientProvider
+	promClientProvider *promclient.Provider
+}
+
+type fakeHttpClientProvider struct {
+	httpclient.Provider
+
+	opts sdkhttpclient.Options
+}
+
+func (p *fakeHttpClientProvider) GetTransport(opts ...sdkhttpclient.Options) (http.RoundTripper, error) {
+	p.opts = opts[0]
+	return http.DefaultTransport, nil
+}
+
+func (p *fakeHttpClientProvider) middlewares() []string {
+	var middlewareNames []string
+	for _, m := range p.opts.Middlewares {
+		mw, ok := m.(sdkhttpclient.MiddlewareName)
+		if !ok {
+			panic("unexpected middleware type")
+		}
+
+		middlewareNames = append(middlewareNames, mw.MiddlewareName())
+	}
+	return middlewareNames
+}

pkg/tsdb/prometheus/prometheus.go

@@ -6,18 +6,17 @@ import (
 	"errors"
 	"fmt"
 	"regexp"
-	"strings"
+
+	"github.com/grafana/grafana/pkg/tsdb/prometheus/promclient"
 
 	"github.com/grafana/grafana-plugin-sdk-go/backend"
 	"github.com/grafana/grafana-plugin-sdk-go/backend/datasource"
-	sdkhttpclient "github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
 	"github.com/grafana/grafana-plugin-sdk-go/backend/instancemgmt"
 	"github.com/grafana/grafana/pkg/infra/httpclient"
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/plugins"
 	"github.com/grafana/grafana/pkg/plugins/backendplugin/coreplugin"
 	"github.com/grafana/grafana/pkg/tsdb/intervalv2"
-	"github.com/prometheus/client_golang/api"
 	apiv1 "github.com/prometheus/client_golang/api/prometheus/v1"
 )
 
@@ -52,56 +51,16 @@ func ProvideService(httpClientProvider httpclient.Provider, registrar plugins.Co
 	return s, nil
 }
 
-func forceHttpGet(settingsJson map[string]interface{}) bool {
-	methodInterface, exists := settingsJson["httpMethod"]
-	if !exists {
-		return false
-	}
-
-	method, ok := methodInterface.(string)
-	if !ok {
-		return false
-	}
-
-	if strings.ToLower(method) != "get" {
-		return false
-	}
-
-	return true
-}
-
 func newInstanceSettings(httpClientProvider httpclient.Provider) datasource.InstanceFactoryFunc {
 	return func(settings backend.DataSourceInstanceSettings) (instancemgmt.Instance, error) {
-		jsonData := map[string]interface{}{}
+		var jsonData promclient.JsonData
 		err := json.Unmarshal(settings.JSONData, &jsonData)
 		if err != nil {
 			return nil, fmt.Errorf("error reading settings: %w", err)
 		}
-		httpCliOpts, err := settings.HTTPClientOptions()
-		if err != nil {
-			return nil, fmt.Errorf("error getting http options: %w", err)
-		}
 
-		// Set SigV4 service namespace
-		if httpCliOpts.SigV4 != nil {
-			httpCliOpts.SigV4.Service = "aps"
-		}
-
-		// timeInterval can be a string or can be missing.
-		// if it is missing, we set it to empty-string
-		timeInterval := ""
-
-		timeIntervalJson := jsonData["timeInterval"]
-		if timeIntervalJson != nil {
-			// if it is not nil, it must be a string
-			var ok bool
-			timeInterval, ok = timeIntervalJson.(string)
-			if !ok {
-				return nil, errors.New("invalid time-interval provided")
-			}
-		}
-
-		client, err := createClient(settings.URL, httpCliOpts, httpClientProvider, forceHttpGet(jsonData))
+		p := promclient.NewProvider(settings, jsonData, httpClientProvider, plog)
+		pc, err := promclient.NewProviderCache(p, jsonData)
 		if err != nil {
 			return nil, err
 		}
@@ -109,8 +68,8 @@ func newInstanceSettings(httpClientProvider httpclient.Provider) datasource.Inst
 		mdl := DatasourceInfo{
 			ID:           settings.ID,
 			URL:          settings.URL,
-			TimeInterval: timeInterval,
-			promClient:   client,
+			TimeInterval: jsonData.TimeInterval,
+			getClient:    pc.GetClient,
 		}
 
 		return mdl, nil
@@ -139,32 +98,6 @@ func (s *Service) QueryData(ctx context.Context, req *backend.QueryDataRequest)
 	return result, err
 }
 
-func createClient(url string, httpOpts sdkhttpclient.Options, clientProvider httpclient.Provider, forceHttpGet bool) (apiv1.API, error) {
-	customParamsMiddleware := customQueryParametersMiddleware(plog)
-	middlewares := []sdkhttpclient.Middleware{customParamsMiddleware}
-	if forceHttpGet {
-		middlewares = append(middlewares, forceHttpGetMiddleware(plog))
-	}
-	httpOpts.Middlewares = middlewares
-
-	roundTripper, err := clientProvider.GetTransport(httpOpts)
-	if err != nil {
-		return nil, err
-	}
-
-	cfg := api.Config{
-		Address:      url,
-		RoundTripper: roundTripper,
-	}
-
-	client, err := api.NewClient(cfg)
-	if err != nil {
-		return nil, err
-	}
-
-	return apiv1.NewAPI(client), nil
-}
-
 func (s *Service) getDSInfo(pluginCtx backend.PluginContext) (*DatasourceInfo, error) {
 	i, err := s.im.Get(pluginCtx)
 	if err != nil {

pkg/tsdb/prometheus/time_series_query.go

@@ -48,7 +48,10 @@ const (
 )
 
 func (s *Service) executeTimeSeriesQuery(ctx context.Context, req *backend.QueryDataRequest, dsInfo *DatasourceInfo) (*backend.QueryDataResponse, error) {
-	client := dsInfo.promClient
+	client, err := dsInfo.getClient(req.Headers)
+	if err != nil {
+		return nil, err
+	}
 
 	result := backend.QueryDataResponse{
 		Responses: backend.Responses{},

pkg/tsdb/prometheus/types.go

@@ -11,9 +11,11 @@ type DatasourceInfo struct {
 	URL          string
 	TimeInterval string
 
-	promClient apiv1.API
+	getClient clientGetter
 }
 
+type clientGetter func(map[string]string) (apiv1.API, error)
+
 type PrometheusQuery struct {
 	Expr          string
 	Step          time.Duration