Datasource: Improve default timeout settings for HTTP client provider (#36621)

Make sure that default timeout settings are based on configuration
parameters. This now applies for core data sources using old TSDB
contracts and new SDK contracts. Before it was only applied for old TSDB
contracts.
Also moves global setting variables to non-global (setting.Cfg).

pkg/infra/httpclient/httpclientprovider/http_client_provider.go

@@ -3,6 +3,7 @@ package httpclientprovider
 import (
 	"fmt"
 	"net/http"
+	"time"
 
 	sdkhttpclient "github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
 	"github.com/grafana/grafana/pkg/infra/httpclient"
@@ -18,6 +19,7 @@ var newProviderFunc = sdkhttpclient.NewProvider
 func New(cfg *setting.Cfg) httpclient.Provider {
 	logger := log.New("httpclient")
 	userAgent := fmt.Sprintf("Grafana/%s", cfg.BuildVersion)
+
 	middlewares := []sdkhttpclient.Middleware{
 		TracingMiddleware(logger),
 		DataSourceMetricsMiddleware(),
@@ -30,6 +32,8 @@ func New(cfg *setting.Cfg) httpclient.Provider {
 		middlewares = append(middlewares, SigV4Middleware())
 	}
 
+	setDefaultTimeoutOptions(cfg)
+
 	return newProviderFunc(sdkhttpclient.ProviderOptions{
 		Middlewares: middlewares,
 		ConfigureTransport: func(opts sdkhttpclient.Options, transport *http.Transport) {
@@ -56,3 +60,20 @@ func newConntrackRoundTripper(name string, transport *http.Transport) *http.Tran
 	)
 	return transport
 }
+
+// setDefaultTimeoutOptions overrides the default timeout options for the SDK.
+//
+// Note: Not optimal changing global state, but hard to not do in this case.
+func setDefaultTimeoutOptions(cfg *setting.Cfg) {
+	sdkhttpclient.DefaultTimeoutOptions = sdkhttpclient.TimeoutOptions{
+		Timeout:               time.Duration(cfg.DataProxyTimeout) * time.Second,
+		DialTimeout:           time.Duration(cfg.DataProxyDialTimeout) * time.Second,
+		KeepAlive:             time.Duration(cfg.DataProxyKeepAlive) * time.Second,
+		TLSHandshakeTimeout:   time.Duration(cfg.DataProxyTLSHandshakeTimeout) * time.Second,
+		ExpectContinueTimeout: time.Duration(cfg.DataProxyExpectContinueTimeout) * time.Second,
+		MaxConnsPerHost:       cfg.DataProxyMaxConnsPerHost,
+		MaxIdleConns:          cfg.DataProxyMaxIdleConns,
+		MaxIdleConnsPerHost:   cfg.DataProxyMaxIdleConns,
+		IdleConnTimeout:       time.Duration(cfg.DataProxyIdleConnTimeout) * time.Second,
+	}
+}