feat(api): add debug route

pkg/gotenberg/debug.go

@@ -1,4 +1,65 @@
 package gotenberg
 
-// Version is the... version of the Gotenberg application.
-var Version = "snapshot"
+import (
+	"runtime"
+	"sync"
+
+	flag "github.com/spf13/pflag"
+)
+
+// DebugInfo gathers data for debugging.
+type DebugInfo struct {
+	Version               string                            `json:"version"`
+	Architecture          string                            `json:"architecture"`
+	Modules               []string                          `json:"modules"`
+	ModulesAdditionalData map[string]map[string]interface{} `json:"modules_additional_data"`
+	Flags                 map[string]interface{}            `json:"flags"`
+}
+
+// BuildDebug builds the debug data from modules.
+func BuildDebug(ctx *Context) {
+	debugMu.Lock()
+	defer debugMu.Unlock()
+
+	debug = &DebugInfo{
+		Version:               Version,
+		Architecture:          runtime.GOARCH,
+		Modules:               make([]string, len(ctx.moduleInstances)),
+		ModulesAdditionalData: make(map[string]map[string]interface{}),
+		Flags:                 make(map[string]interface{}),
+	}
+
+	i := 0
+	for ID, mod := range ctx.moduleInstances {
+		debug.Modules[i] = ID
+		i++
+
+		debuggable, ok := mod.(Debuggable)
+		if !ok {
+			continue
+		}
+
+		debug.ModulesAdditionalData[ID] = debuggable.Debug()
+	}
+
+	ctx.ParsedFlags().VisitAll(func(f *flag.Flag) {
+		debug.Flags[f.Name] = f.Value.String()
+	})
+}
+
+// Debug returns the debug data.
+func Debug() DebugInfo {
+	debugMu.Lock()
+	defer debugMu.Unlock()
+
+	if debug == nil {
+		return DebugInfo{}
+	}
+
+	return *debug
+}
+
+var (
+	debug   *DebugInfo
+	debugMu sync.Mutex
+)

pkg/gotenberg/debug_test.go

@@ -0,0 +1,72 @@
+package gotenberg
+
+import (
+	"reflect"
+	"runtime"
+	"testing"
+
+	flag "github.com/spf13/pflag"
+)
+
+func TestBuildDebug(t *testing.T) {
+	if !reflect.DeepEqual(Debug(), DebugInfo{}) {
+		t.Errorf("Debug() should return empty debug data")
+	}
+
+	fs := flag.NewFlagSet("gotenberg", flag.ExitOnError)
+	fs.String("foo", "bar", "Set foo")
+	ctx := NewContext(ParsedFlags{
+		FlagSet: fs,
+	}, func() []ModuleDescriptor {
+		mod1 := &struct {
+			ModuleMock
+		}{}
+		mod1.DescriptorMock = func() ModuleDescriptor {
+			return ModuleDescriptor{ID: "foo", New: func() Module { return mod1 }}
+		}
+		mod2 := &struct {
+			ModuleMock
+			DebuggableMock
+		}{}
+		mod2.DescriptorMock = func() ModuleDescriptor {
+			return ModuleDescriptor{ID: "bar", New: func() Module { return mod2 }}
+		}
+		mod2.DebugMock = func() map[string]interface{} {
+			return map[string]interface{}{
+				"foo": "bar",
+			}
+		}
+
+		return []ModuleDescriptor{mod1.Descriptor(), mod2.Descriptor()}
+	}())
+
+	// Load modules.
+	_, err := ctx.Modules(new(Module))
+	if err != nil {
+		t.Errorf("expected no error but got: %v", err)
+	}
+
+	// Build debug data.
+	BuildDebug(ctx)
+
+	expect := DebugInfo{
+		Version:      Version,
+		Architecture: runtime.GOARCH,
+		Modules: []string{
+			"foo",
+			"bar",
+		},
+		ModulesAdditionalData: map[string]map[string]interface{}{
+			"bar": {
+				"foo": "bar",
+			},
+		},
+		Flags: map[string]interface{}{
+			"foo": "bar",
+		},
+	}
+
+	if !reflect.DeepEqual(expect, Debug()) {
+		t.Errorf("expected '%+v', bug got '%+v'", expect, Debug())
+	}
+}

pkg/gotenberg/mocks.go

@@ -34,6 +34,14 @@ func (mod *ValidatorMock) Validate() error {
 	return mod.ValidateMock()
 }
 
+type DebuggableMock struct {
+	DebugMock func() map[string]interface{}
+}
+
+func (mod *DebuggableMock) Debug() map[string]interface{} {
+	return mod.DebugMock()
+}
+
 // PdfEngineMock is a mock for the [PdfEngine] interface.
 //
 //nolint:dupl

pkg/gotenberg/mocks_test.go

@@ -48,6 +48,21 @@ func TestValidatorMock(t *testing.T) {
 	}
 }
 
+func TestDebuggableMock(t *testing.T) {
+	mock := &DebuggableMock{
+		DebugMock: func() map[string]interface{} {
+			return map[string]interface{}{
+				"foo": "bar",
+			}
+		},
+	}
+
+	d := mock.Debug()
+	if d == nil {
+		t.Errorf("expected debug data, but got nil")
+	}
+}
+
 func TestPDFEngineMock(t *testing.T) {
 	mock := &PdfEngineMock{
 		MergeMock: func(ctx context.Context, logger *zap.Logger, inputPaths []string, outputPath string) error {

pkg/gotenberg/modules.go

@@ -75,6 +75,12 @@ type SystemLogger interface {
 	SystemMessages() []string
 }
 
+// Debuggable is a module interface for modules which want to provide
+// additional debug data.
+type Debuggable interface {
+	Debug() map[string]interface{}
+}
+
 // MustRegisterModule registers a module.
 //
 // To register a module, create an init() method in the module main go file:

pkg/gotenberg/version.go

@@ -0,0 +1,4 @@
+package gotenberg
+
+// Version is the... version of the Gotenberg application.
+var Version = "snapshot"