Added a new rpc call workflow.GetWorkflowContextList to be used by bo…

…ots (tinkerbell#237)

## Description
As the worker starts, Boots checks [if there is a workflow](https://github.com/tinkerbell/boots/blob/master/packet/endpoints.go#L48) defined for that worker. If yes, it will continue to PXE and it will not otherwise. (more context [here](tinkerbell/smee#50)).

The PR introduces a new RPC that can be used by Boots to get the workflow contexts without having to maintain a gRPC stream. 

## Why is this needed

Recently there have been [changes](tinkerbell#222) in Tink, to allow a worker to maintain a gRPC stream with the server to get the workflows. The same RPC was being by boots. 

## How Has This Been Tested?
Still a WIP. 

## How are existing users impacted? What migration steps/scripts do we need?

No direct impact on users.

## Checklist:

I have:

- [ ] updated the documentation and/or roadmap (if required)
- [ ] added unit or e2e tests
- [ ] provided instructions on how to upgrade

db/workflow.go

@@ -344,8 +344,8 @@ func GetWorkflowDataVersion(ctx context.Context, db *sql.DB, workflowID string)
 	return getLatestVersionWfData(ctx, db, workflowID)
 }
 
-// GetfromWfWorkflowTable : returns the list of workflows for a particular worker
-func GetfromWfWorkflowTable(db *sql.DB, id string) ([]string, error) {
+// GetWorkflowsForWorker : returns the list of workflows for a particular worker
+func GetWorkflowsForWorker(db *sql.DB, id string) ([]string, error) {
 	rows, err := db.Query(`
 	SELECT workflow_id
 	FROM workflow_worker_map

executor/executor.go

@@ -19,14 +19,10 @@ var (
 
 // GetWorkflowContexts implements tinkerbell.GetWorkflowContexts
 func GetWorkflowContexts(req *pb.WorkflowContextRequest, stream pb.WorkflowSvc_GetWorkflowContextsServer, sdb *sql.DB) error {
-	if len(req.WorkerId) == 0 {
-		return status.Errorf(codes.InvalidArgument, "worker_id is invalid")
-	}
-	wfs, _ := db.GetfromWfWorkflowTable(sdb, req.WorkerId)
-	if wfs == nil {
-		return status.Errorf(codes.InvalidArgument, "No workflow found for worker %s ", req.GetWorkerId())
+	wfs, err := getWorkflowsForWorker(sdb, req.WorkerId)
+	if err != nil {
+		return err
 	}
-
 	for _, wf := range wfs {
 		wfContext, err := db.GetWorkflowContexts(context.Background(), sdb, wf)
 		if err != nil {
@@ -39,6 +35,36 @@ func GetWorkflowContexts(req *pb.WorkflowContextRequest, stream pb.WorkflowSvc_G
 	return nil
 }
 
+// GetWorkflowContextList implements tinkerbell.GetWorkflowContextList
+func GetWorkflowContextList(context context.Context, req *pb.WorkflowContextRequest, sdb *sql.DB) (*pb.WorkflowContextList, error) {
+	wfs, err := getWorkflowsForWorker(sdb, req.WorkerId)
+	if err != nil {
+		return nil, err
+	}
+	wfContexts := []*pb.WorkflowContext{}
+	for _, wf := range wfs {
+		wfContext, err := db.GetWorkflowContexts(context, sdb, wf)
+		if err != nil {
+			return nil, status.Errorf(codes.Aborted, "Invalid workflow %s found for worker %s", wf, req.WorkerId)
+		}
+		wfContexts = append(wfContexts, wfContext)
+	}
+	return &pb.WorkflowContextList{
+		WorkflowContexts: wfContexts,
+	}, nil
+}
+
+func getWorkflowsForWorker(sdb *sql.DB, id string) ([]string, error) {
+	if len(id) == 0 {
+		return nil, status.Errorf(codes.InvalidArgument, "worker_id is invalid")
+	}
+	wfs, _ := db.GetWorkflowsForWorker(sdb, id)
+	if wfs == nil {
+		return nil, status.Errorf(codes.InvalidArgument, "Worker not found for any workflows")
+	}
+	return wfs, nil
+}
+
 // GetWorkflowActions implements tinkerbell.GetWorkflowActions
 func GetWorkflowActions(context context.Context, req *pb.WorkflowActionsRequest, sdb *sql.DB) (*pb.WorkflowActionList, error) {
 	wfID := req.GetWorkflowId()

go.mod

@@ -46,13 +46,13 @@ require (
 	go.uber.org/atomic v1.2.0 // indirect
 	go.uber.org/multierr v1.1.0 // indirect
 	go.uber.org/zap v1.7.1 // indirect
-	golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2
 	golang.org/x/net v0.0.0-20200324143707-d3edc9973b7e // indirect
 	golang.org/x/sys v0.0.0-20200331124033-c3d80250170d // indirect
 	golang.org/x/text v0.3.2 // indirect
 	golang.org/x/time v0.0.0-20191024005414-555d28b269f0 // indirect
 	google.golang.org/genproto v0.0.0-20200513103714-09dca8ec2884
 	google.golang.org/grpc v1.29.1
+	google.golang.org/protobuf v1.23.0
 	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
 	gopkg.in/yaml.v2 v2.2.3
 	gotest.tools v2.2.0+incompatible // indirect

grpc-server/tinkerbell.go

@@ -12,6 +12,11 @@ func (s *server) GetWorkflowContexts(req *pb.WorkflowContextRequest, stream pb.W
 	return exec.GetWorkflowContexts(req, stream, s.db)
 }
 
+// GetWorkflowContextList implements tinkerbell.GetWorkflowContextList
+func (s *server) GetWorkflowContextList(context context.Context, req *pb.WorkflowContextRequest) (*pb.WorkflowContextList, error) {
+	return exec.GetWorkflowContextList(context, req, s.db)
+}
+
 // GetWorkflowActions implements tinkerbell.GetWorkflowActions
 func (s *server) GetWorkflowActions(context context.Context, req *pb.WorkflowActionsRequest) (*pb.WorkflowActionList, error) {
 	return exec.GetWorkflowActions(context, req, s.db)