Pass original context to trace volume create steps across grpc nodes.

Pass the original context to the runStepOn() function so that it can be
used by the opensensus grpc plugin to trace the calls on other nodes in
the gluster cluster. Also, append the requestID to the span info in
addition to the associated function name so that the operation can be
identified on the tracing UI application.

Signed-off-by: Sridhar Seshasayee <sseshasa@redhat.com>

glusterd2/transaction/rpc-client.go

@@ -16,7 +16,7 @@ import (
 )
 
 // runStepOn will run the step on the specified node
-func runStepOn(step string, node uuid.UUID, c TxnCtx) error {
+func runStepOn(origCtx netctx.Context, step string, node uuid.UUID, c TxnCtx) error {
 	// TODO: I'm creating connections on demand. This should be changed so that
 	// we have long term connections.
 	p, err := peer.GetPeerF(node.String())
@@ -73,7 +73,7 @@ func runStepOn(step string, node uuid.UUID, c TxnCtx) error {
 
 	var rsp *TxnStepResp
 
-	rsp, err = client.RunStep(netctx.TODO(), req)
+	rsp, err = client.RunStep(origCtx, req)
 	if err != nil {
 		logger.WithFields(log.Fields{
 			"error": err,

glusterd2/transaction/rpc-service.go

@@ -7,6 +7,7 @@ import (
 	"github.com/gluster/glusterd2/glusterd2/servers/peerrpc"
 
 	log "github.com/sirupsen/logrus"
+	"go.opencensus.io/trace"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 )
@@ -37,6 +38,13 @@ func (p *txnSvc) RunStep(rpcCtx context.Context, req *TxnStepReq) (*TxnStepResp,
 	logger = ctx.Logger().WithField("stepfunc", req.StepFunc)
 	logger.Debug("RunStep request received")
 
+	if rpcCtx != nil {
+		reqID := ctx.GetTxnReqID()
+		spanName := req.StepFunc + " ReqID:" + reqID
+		_, span := trace.StartSpan(rpcCtx, spanName)
+		defer span.End()
+	}
+
 	f, ok = getStepFunc(req.StepFunc)
 	if !ok {
 		err = errors.New("step function not found in registry")

glusterd2/transaction/step.go

@@ -139,7 +139,7 @@ func runStepFuncOnNode(origCtx context.Context, stepName string, ctx TxnCtx, nod
 		err = runStepFuncLocally(origCtx, stepName, ctx)
 	} else {
 		// remote node
-		err = runStepOn(stepName, node, ctx)
+		err = runStepOn(origCtx, stepName, node, ctx)
 	}
 
 	respCh <- stepPeerResp{node, err}