open-consul/agent/xds/serverlessplugin/patcher.go

package serverlessplugin

import (
	envoy_cluster_v3 "github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3"
	envoy_listener_v3 "github.com/envoyproxy/go-control-plane/envoy/config/listener/v3"
	envoy_route_v3 "github.com/envoyproxy/go-control-plane/envoy/config/route/v3"

	"github.com/hashicorp/consul/agent/xds/xdscommon"
	"github.com/hashicorp/consul/api"
)

// patcher is the interface that each serverless integration must implement. It
// is responsible for modifying the xDS structures based on only the state of
// the patcher.
type patcher interface {
	// CanPatch determines if the patcher can mutate resources for the given api.ServiceKind
	CanPatch(api.ServiceKind) bool

	// patchRoute patches a route to include the custom Envoy configuration
	// PatchCluster patches a cluster to include the custom Envoy configuration
	// required to integrate with the serverless integration.
	PatchRoute(*envoy_route_v3.RouteConfiguration) (*envoy_route_v3.RouteConfiguration, bool, error)

	// PatchCluster patches a cluster to include the custom Envoy configuration
	// required to integrate with the serverless integration.
	PatchCluster(*envoy_cluster_v3.Cluster) (*envoy_cluster_v3.Cluster, bool, error)

	// PatchFilter patches an Envoy filter to include the custom Envoy
	// configuration required to integrate with the serverless integration.
	PatchFilter(*envoy_listener_v3.Filter) (*envoy_listener_v3.Filter, bool, error)
}

type patchers map[api.CompoundServiceName]patcher

func makePatcher(config xdscommon.ExtensionConfiguration) patcher {
	for _, constructor := range patchConstructors {
		patcher, ok := constructor(config.EnvoyExtension, config.OutgoingProxyKind())
		if ok {
			return patcher
		}
	}

	return nil
}

// patchConstructor is used to construct patchers based on
// xdscommon.ServiceConfig. This function contains all of the logic around
// turning Meta data into the patcher.
type patchConstructor func(extension api.EnvoyExtension, upstreamKind api.ServiceKind) (patcher, bool)

// patchConstructors contains all patchers that getPatchers tries to create.
var patchConstructors = []patchConstructor{makeLambdaPatcher}