Rsync & AppContext

1 Appcontext Data Format
2 AppContext Library
3 Creating AppContext Flow
- 3.1 Creating AppContext
4 Action Controller flow
- 4.1 Creating AppContext
5 Placement Controller flow
- 5.1 Creating AppContext
6 RPC Communication
7 AppContext API

Appcontext Data Format

The following figure depicts the hierarchical data store for runtime data. The notes in the figure is additional data stored in each type of node. Rsync uses this information to schedule resources. Status is updated by Rsync.

AppContext Library

To create and work with appcontext a library is provided: github.com/onap/multicloud-k8s/src/orchestrator/pkg/appcontext

Creating AppContext Flow

The following example shows how to create an AppContext for a CompositeApp with one App. This pattern is used by controllers that are creating new AppContextID. Examples are Orchestrator, NCM(create networks), CLM(create clusters) and DCM(create logical clouds)

Creating AppContext

import "github.com/onap/multicloud-k8s/src/orchestrator/pkg/appcontext"
func createAppContextWithOneApp(appName string)	
{
	context := appcontext.AppContext{}
	ctxVal, err := context.InitAppContext()
	if err != nil {
		return nil
	}
	
    handle, err := context.CreateCompositeApp()
	if err != nil {
		return nil
	}
	// This is optional
    err = context.AddCompositeAppMeta(appcontext.CompositeAppMeta{Project: p, CompositeApp: ca, Version: v, Release: rName})
	if err != nil {
		return nil
	}
	
    appHandle, err := context.AddApp(handle, appName)
	if err != nil {
		return nil
	}
	
    // Iterate through cluster list and add all the clusters
	for _, cluster := range clusterList {
		clusterName := strings.Join([]string{cluster.ClusterProvider, "+", cluster.ClusterName}, "")
		clusterHandle, err := context.AddCluster(appHandle, clusterName)

		if err != nil {
			return nil
		}

		// Add resource
		_, err = context.AddResource(clusterHandle, nameofRes1, resYaml1)
		if err != nil {
			return nil
		}
		// Add resource
		_, err = context.AddResource(clusterHandle, nameofRes2, resYaml2)
		if err != nil {
			return nil
		}
		// Add Resource Order 
		resOrder, err := json.Marshal(map[string][]string{"resorder": []string{nameofRes1, nameofRes2}})
		if err != nil {
			return nil
		}
		_, err = context.AddInstruction(clusterHandle, "resource", "order", string(resOrder))
		if err != nil {
			return nil
		}
	}
}

Action Controller flow

Action controllers will follow the following pattern to add and update existing resources in AppContext. AppContextId is provided to the action controllers from the orchestrator using gRpc call. Examples are ovnAction controller

Creating AppContext

import "github.com/onap/multicloud-k8s/src/orchestrator/pkg/appcontext"
func updateAppContext(appContextId string)	
{
	var context appcontext.AppContext
	_, err = context.LoadAppContext(appContextId)
	if err != nil {
		return nil
	}

   // Get all clusters from the AppContext for an App
	clusters, err := context.GetClusterNames("testApp")
	for _, c := range clusters {
		// Resources in AppContext are named is the format (ResourceName+ResourceType) "res3+Deployment"
		appContextResName := strings.Join([]string{"resName", "Deployment"}, "+"
		rh, err := context.GetResourceHandle("testApp", c, appContextResName )
		if err != nil {
			return err
		}
		r, err := context.GetValue(rh)
		if err != nil {
			return err
		}
		// Unmarshal resource extract the Kubernetes object definition
		kubObj, err := runtime.Decode(scheme.Codecs.UniversalDeserializer(), []byte(r.(string)))
		//Modify resource to add/modify existing contents
        ......
		// Put back updated resource in AppContext
		err = context.UpdateResourceValue(rh, updatedRes)
		if err != nil {
			return nil
		}
}

Placement Controller flow

Placement controllers will follow the following pattern to select a cluster from group of clusters for an App. AppContextId is provided to the placement controllers from the orchestrator using gRpc call.

Creating AppContext

func placement(appContextId string)	
{
	var context appcontext.AppContext
	_, err = context.LoadAppContext(appContextId)
	if err != nil {
		return nil
	}
   // Get  AppContext for an App
  gmap, err := context.GetClusterGroupMap("testApp")
  // sample output {"1":["cluster_provider1+clusterName3","cluster_provider1+clusterName5"],"2":["cluster_provider2+clusterName4","cluster_provider2+clusterName6"]}
  for gr, cl := range gmap {
	for i, cn := range cl {
		// Based on the output decide which cluster is not suitable
   		.......
        //Delete the cluster not suitable
		ch, err := ct.GetClusterHandle(an, cn)
		err = ct.DeleteCluster(ch)
	}	
  }
}

RPC Communication

AppContext API

GoDoc: package appcontext // import "github.com/onap/multicloud-k8s/src/orchestrator/pkg/appcontext"

RSYNC registration outside of orchestration.

There have been use cases when we need to invoke RSYNC outside of orchestrator.
For such cases, we have provided a method - NewRsyncInfo()
This method directly takes in Rsync controller name, hostname and port number.
After that , we have a method initRsyncClient() which creates the required gRPC client connection.
Use the above two methods to register a rsync controller outside of orchestrator.

The relevant portion in the code is shown below :

File to import : orchestrator/pkg/grpc/installappclient/client.go