Chore: Refactor usage of legacy data contracts (#41218)

Refactor usage of legacy data contracts. Moves legacy data contracts 
to pkg/tsdb/legacydata package.
Refactor pkg/expr to be a proper service/dependency that can be provided 
to wire to remove some unneeded dependencies to SSE in ngalert and other places.
Refactor pkg/expr to not use the legacydata,RequestHandler and use 
backend.QueryDataHandler instead.

pkg/services/ngalert/api/api.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/grafana/grafana/pkg/api/routing"
+	"github.com/grafana/grafana/pkg/expr"
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/services/datasourceproxy"
 	"github.com/grafana/grafana/pkg/services/datasources"
@@ -18,7 +19,6 @@ import (
 	"github.com/grafana/grafana/pkg/services/quota"
 	"github.com/grafana/grafana/pkg/services/secrets"
 	"github.com/grafana/grafana/pkg/setting"
-	"github.com/grafana/grafana/pkg/tsdb"
 )
 
 // timeNow makes it possible to test usage of time
@@ -54,7 +54,7 @@ type API struct {
 	Cfg                  *setting.Cfg
 	DatasourceCache      datasources.CacheService
 	RouteRegister        routing.RouteRegister
-	DataService          *tsdb.Service
+	ExpressionService    *expr.Service
 	QuotaService         *quota.QuotaService
 	Schedule             schedule.ScheduleService
 	RuleStore            store.RuleStore
@@ -93,11 +93,11 @@ func (api *API) RegisterAPIEndpoints(m *metrics.API) {
 		RulerSrv{DatasourceCache: api.DatasourceCache, QuotaService: api.QuotaService, manager: api.StateManager, store: api.RuleStore, log: logger},
 	), m)
 	api.RegisterTestingApiEndpoints(TestingApiSrv{
-		AlertingProxy:   proxy,
-		Cfg:             api.Cfg,
-		DataService:     api.DataService,
-		DatasourceCache: api.DatasourceCache,
-		log:             logger,
+		AlertingProxy:     proxy,
+		Cfg:               api.Cfg,
+		ExpressionService: api.ExpressionService,
+		DatasourceCache:   api.DatasourceCache,
+		log:               logger,
 	}, m)
 	api.RegisterConfigurationApiEndpoints(AdminSrv{
 		store:     api.AdminConfigStore,

pkg/services/ngalert/api/api_testing.go

@@ -8,22 +8,22 @@ import (
 	"strconv"
 
 	"github.com/grafana/grafana/pkg/api/response"
+	"github.com/grafana/grafana/pkg/expr"
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/services/datasources"
 	apimodels "github.com/grafana/grafana/pkg/services/ngalert/api/tooling/definitions"
 	"github.com/grafana/grafana/pkg/services/ngalert/eval"
 	"github.com/grafana/grafana/pkg/setting"
-	"github.com/grafana/grafana/pkg/tsdb"
 	"github.com/grafana/grafana/pkg/web"
 )
 
 type TestingApiSrv struct {
 	*AlertingProxy
-	Cfg             *setting.Cfg
-	DataService     *tsdb.Service
-	DatasourceCache datasources.CacheService
-	log             log.Logger
+	Cfg               *setting.Cfg
+	ExpressionService *expr.Service
+	DatasourceCache   datasources.CacheService
+	log               log.Logger
 }
 
 func (srv TestingApiSrv) RouteTestRuleConfig(c *models.ReqContext, body apimodels.TestRulePayload) response.Response {
@@ -32,7 +32,7 @@ func (srv TestingApiSrv) RouteTestRuleConfig(c *models.ReqContext, body apimodel
 		if body.Type() != apimodels.GrafanaBackend || body.GrafanaManagedCondition == nil {
 			return ErrResp(http.StatusBadRequest, errors.New("unexpected payload"), "")
 		}
-		return conditionEval(c, *body.GrafanaManagedCondition, srv.DatasourceCache, srv.DataService, srv.Cfg, srv.log)
+		return conditionEval(c, *body.GrafanaManagedCondition, srv.DatasourceCache, srv.ExpressionService, srv.Cfg, srv.log)
 	}
 
 	if body.Type() != apimodels.LoTexRulerBackend {
@@ -86,7 +86,7 @@ func (srv TestingApiSrv) RouteEvalQueries(c *models.ReqContext, cmd apimodels.Ev
 	}
 
 	evaluator := eval.Evaluator{Cfg: srv.Cfg, Log: srv.log}
-	evalResults, err := evaluator.QueriesAndExpressionsEval(c.SignedInUser.OrgId, cmd.Data, now, srv.DataService)
+	evalResults, err := evaluator.QueriesAndExpressionsEval(c.SignedInUser.OrgId, cmd.Data, now, srv.ExpressionService)
 	if err != nil {
 		return ErrResp(http.StatusBadRequest, err, "Failed to evaluate queries and expressions")
 	}

pkg/services/ngalert/api/util.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/grafana/grafana-plugin-sdk-go/data"
 	"github.com/grafana/grafana/pkg/api/response"
+	"github.com/grafana/grafana/pkg/expr"
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/services/datasourceproxy"
@@ -21,7 +22,6 @@ import (
 	"github.com/grafana/grafana/pkg/services/ngalert/eval"
 	ngmodels "github.com/grafana/grafana/pkg/services/ngalert/models"
 	"github.com/grafana/grafana/pkg/setting"
-	"github.com/grafana/grafana/pkg/tsdb"
 	"github.com/grafana/grafana/pkg/util"
 	"github.com/grafana/grafana/pkg/web"
 	"github.com/pkg/errors"
@@ -223,7 +223,7 @@ func validateQueriesAndExpressions(data []ngmodels.AlertQuery, user *models.Sign
 	return refIDs, nil
 }
 
-func conditionEval(c *models.ReqContext, cmd ngmodels.EvalAlertConditionCommand, datasourceCache datasources.CacheService, dataService *tsdb.Service, cfg *setting.Cfg, log log.Logger) response.Response {
+func conditionEval(c *models.ReqContext, cmd ngmodels.EvalAlertConditionCommand, datasourceCache datasources.CacheService, expressionService *expr.Service, cfg *setting.Cfg, log log.Logger) response.Response {
 	evalCond := ngmodels.Condition{
 		Condition: cmd.Condition,
 		OrgID:     c.SignedInUser.OrgId,
@@ -239,7 +239,7 @@ func conditionEval(c *models.ReqContext, cmd ngmodels.EvalAlertConditionCommand,
 	}
 
 	evaluator := eval.Evaluator{Cfg: cfg, Log: log}
-	evalResults, err := evaluator.ConditionEval(&evalCond, now, dataService)
+	evalResults, err := evaluator.ConditionEval(&evalCond, now, expressionService)
 	if err != nil {
 		return ErrResp(http.StatusBadRequest, err, "Failed to evaluate conditions")
 	}