Cloudwatch: use shared library for aws auth (#29550) (#31946)

* use sdk for handling auth

* fix broken test

* lint fixes

Co-authored-by: Erik Sundell <erik.sundell87@gmail.com>
(cherry picked from commit 9dd1d5f553)

Co-authored-by: Ryan McKinley <ryantxu@gmail.com>

pkg/plugins/backendplugin/manager.go

@@ -9,9 +9,11 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
+	"strings"
 	"sync"
 	"time"
 
+	"github.com/grafana/grafana-aws-sdk/pkg/awsds"
 	"github.com/grafana/grafana-plugin-sdk-go/backend"
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/models"
@@ -108,6 +110,8 @@ func (m *manager) Register(pluginID string, factory PluginFactoryFunc) error {
 		}
 	}
 
+	hostEnv = append(hostEnv, m.getAWSEnvironmentVariables()...)
+
 	env := pluginSettings.ToEnv("GF_PLUGIN", hostEnv)
 
 	pluginLogger := m.logger.New("pluginId", pluginID)
@@ -121,6 +125,18 @@ func (m *manager) Register(pluginID string, factory PluginFactoryFunc) error {
 	return nil
 }
 
+func (m *manager) getAWSEnvironmentVariables() []string {
+	variables := []string{}
+	if m.Cfg.AWSAssumeRoleEnabled {
+		variables = append(variables, awsds.AssumeRoleEnabledEnvVarKeyName+"=true")
+	}
+	if len(m.Cfg.AWSAllowedAuthProviders) > 0 {
+		variables = append(variables, awsds.AllowedAuthProvidersEnvVarKeyName+"="+strings.Join(m.Cfg.AWSAllowedAuthProviders, ","))
+	}
+
+	return variables
+}
+
 // start starts all managed backend plugins
 func (m *manager) start(ctx context.Context) {
 	m.pluginsMu.RLock()