feat: add priority to modules

router-tests/modules/module_test.go

@@ -2,10 +2,11 @@ package module_test
 
 import (
 	"encoding/json"
+	"testing"
+
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/wundergraph/cosmo/router-tests/testenv"
-	"testing"
 
 	"github.com/wundergraph/cosmo/router/cmd/custom/module"
 	"github.com/wundergraph/cosmo/router/core"

router/cmd/custom/module/module.go

@@ -96,6 +96,8 @@ func (m *MyModule) Module() core.ModuleInfo {
 	return core.ModuleInfo{
 		// This is the ID of your module, it must be unique
 		ID: myModuleID,
+		// The priority of your module, lower numbers are executed first
+		Priority: 1,
 		New: func() core.Module {
 			return &MyModule{}
 		},

router/core/modules.go

@@ -3,7 +3,9 @@ package core
 import (
 	stdContext "context"
 	"fmt"
+	"math"
 	"net/http"
+	"sort"
 	"sync"
 
 	"github.com/pkg/errors"
@@ -39,7 +41,8 @@ type ModuleID string
 
 type ModuleInfo struct {
 	// Name is the name of the module
-	ID ModuleID
+	ID       ModuleID
+	Priority int
 	// New is the function that creates a new instance of the module
 	New func() Module
 }
@@ -67,6 +70,32 @@ func RegisterModule(instance Module) {
 	modules[string(mod.ID)] = mod
 }
 
+// sortModules sorts the modules by priority
+func sortModules(modules map[string]ModuleInfo) []ModuleInfo {
+	var moduleList []ModuleInfo
+	for _, module := range modules {
+		moduleList = append(moduleList, module)
+	}
+
+	sort.Slice(moduleList, func(x, y int) bool {
+		priorityX := moduleList[x].Priority
+		priorityY := moduleList[y].Priority
+		leastPriority := math.MaxInt
+
+		// If priority is 0, treat it as the lowest possible value
+		if priorityX == 0 {
+			priorityX = leastPriority
+		}
+		if priorityY == 0 {
+			priorityY = leastPriority
+		}
+
+		return priorityX < priorityY
+	})
+
+	return moduleList
+}
+
 // Module Interfaces
 
 // RouterMiddlewareHandler allows you to add a middleware to the router.

router/core/modules_test.go

@@ -2,6 +2,7 @@ package core
 
 import (
 	"errors"
+	"github.com/stretchr/testify/assert"
 	"io"
 	"net/http/httptest"
 	"testing"
@@ -51,3 +52,87 @@ func TestSingleError(t *testing.T) {
 
 	require.Equal(t, `{"errors":[{"message":"test"}],"data":null}`, string(body))
 }
+
+func TestSortingModulesByPriority(t *testing.T) {
+	modulesW := make(map[string]ModuleInfo)
+	modulesW["module1_0"] = ModuleInfo{
+		ID: "module1_0",
+		New: func() Module {
+			return nil
+		},
+	}
+	modulesW["module2_0"] = ModuleInfo{
+		ID: "module2_0",
+		New: func() Module {
+			return nil
+		},
+	}
+
+	modulesX := make(map[string]ModuleInfo)
+	modulesX["module1_1"] = ModuleInfo{
+		ID:       "module1_1",
+		Priority: 1,
+		New: func() Module {
+			return nil
+		},
+	}
+	modulesX["module2_2"] = ModuleInfo{
+		ID:       "module2_2",
+		Priority: 2,
+		New: func() Module {
+			return nil
+		},
+	}
+
+	modulesY := make(map[string]ModuleInfo)
+	modulesY["module1_2"] = ModuleInfo{
+		ID:       "module1_2",
+		Priority: 2,
+		New: func() Module {
+			return nil
+		},
+	}
+	modulesY["module2_1"] = ModuleInfo{
+		ID:       "module2_1",
+		Priority: 1,
+		New: func() Module {
+			return nil
+		},
+	}
+
+	modulesZ := make(map[string]ModuleInfo)
+	modulesZ["module1_0"] = ModuleInfo{
+		ID: "module1_0",
+		New: func() Module {
+			return nil
+		},
+	}
+	modulesZ["module2_2"] = ModuleInfo{
+		ID:       "module2_2",
+		Priority: 2,
+		New: func() Module {
+			return nil
+		},
+	}
+
+	sortedModulesW := sortModules(modulesW)
+	assert.Equal(t, 2, len(sortedModulesW))
+
+	sortedModulesX := sortModules(modulesX)
+	assert.Equal(t, ModuleID("module1_1"), sortedModulesX[0].ID)
+	assert.Equal(t, 1, sortedModulesX[0].Priority)
+	assert.Equal(t, ModuleID("module2_2"), sortedModulesX[1].ID)
+	assert.Equal(t, 2, sortedModulesX[1].Priority)
+
+	sortedModulesY := sortModules(modulesY)
+	assert.Equal(t, ModuleID("module2_1"), sortedModulesY[0].ID)
+	assert.Equal(t, 1, sortedModulesY[0].Priority)
+	assert.Equal(t, ModuleID("module1_2"), sortedModulesY[1].ID)
+	assert.Equal(t, 2, sortedModulesY[1].Priority)
+
+	sortedModulesZ := sortModules(modulesZ)
+	assert.Equal(t, ModuleID("module2_2"), sortedModulesZ[0].ID)
+	assert.Equal(t, 2, sortedModulesZ[0].Priority)
+	assert.Equal(t, ModuleID("module1_0"), sortedModulesZ[1].ID)
+	assert.Equal(t, 0, sortedModulesZ[1].Priority)
+}

router/core/router.go

@@ -508,7 +508,9 @@ func (r *Router) listenAndServe(cfg *nodev1.RouterConfig) error {
 }
 
 func (r *Router) initModules(ctx context.Context) error {
-	for _, moduleInfo := range modules {
+	var moduleList = sortModules(modules)
+
+	for _, moduleInfo := range moduleList {
 		now := time.Now()
 
 		moduleInstance := moduleInfo.New()