Exposes the http router to the plugin manager

In order to expose the http router to plugins a private router property was added to the plugin manager along with a GetRouter method to access it. A router is also initialized in the NewRuntime function if one is not provided in the runtime params. Fixes open-policy-agent#2777

Signed-off-by: Branden Horiuchi <Branden.Horiuchi@blackline.com>

plugins/plugins.go

@@ -11,6 +11,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/gorilla/mux"
 	"github.com/open-policy-agent/opa/ast"
 	"github.com/open-policy-agent/opa/bundle"
 	"github.com/open-policy-agent/opa/config"
@@ -185,6 +186,7 @@ type Manager struct {
 	serverInitializedOnce        sync.Once
 	printHook                    print.Hook
 	enablePrintStatements        bool
+	router                       *mux.Router
 }
 
 type managerContextKey string
@@ -336,6 +338,12 @@ func PrintHook(h print.Hook) func(*Manager) {
 	}
 }
 
+func WithRouter(r *mux.Router) func(*Manager) {
+	return func(m *Manager) {
+		m.router = r
+	}
+}
+
 // New creates a new Manager using config.
 func New(raw []byte, id string, store storage.Store, opts ...func(*Manager)) (*Manager, error) {
 
@@ -518,6 +526,13 @@ func (m *Manager) setCompiler(compiler *ast.Compiler) {
 	m.compiler = compiler
 }
 
+// GetRouter returns the managers router if set
+func (m *Manager) GetRouter() *mux.Router {
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	return m.router
+}
+
 // RegisterCompilerTrigger registers for change notifications when the compiler
 // is changed.
 func (m *Manager) RegisterCompilerTrigger(f func(txn storage.Transaction)) {

runtime/runtime.go

@@ -299,6 +299,10 @@ func NewRuntime(ctx context.Context, params Params) (*Runtime, error) {
 		consoleLogger = params.ConsoleLogger
 	}
 
+	if params.Router == nil {
+		params.Router = mux.NewRouter()
+	}
+
 	manager, err := plugins.New(config,
 		params.ID,
 		inmem.New(),
@@ -310,7 +314,8 @@ func NewRuntime(ctx context.Context, params Params) (*Runtime, error) {
 		plugins.ConsoleLogger(consoleLogger),
 		plugins.Logger(logger),
 		plugins.EnablePrintStatements(logger.GetLevel() >= logging.Info),
-		plugins.PrintHook(loggingPrintHook{logger: logger}))
+		plugins.PrintHook(loggingPrintHook{logger: logger}),
+		plugins.WithRouter(params.Router))
 	if err != nil {
 		return nil, errors.Wrap(err, "config error")
 	}