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// Package httpserver provides an HTTP server module for the modular framework.
// This module offers a complete HTTP server implementation with support for
// TLS, automatic certificate management, graceful shutdown, and middleware integration.
//
// The httpserver module features:
// - HTTP and HTTPS server support
// - Automatic TLS certificate generation and management
// - Configurable timeouts and limits
// - Graceful shutdown handling
// - Handler registration and middleware support
// - Health check endpoints
// - Integration with Let's Encrypt for automatic certificates
//
// Usage:
//
// app.RegisterModule(httpserver.NewModule())
//
// The module registers an HTTP server service that can be used by other modules
// to register handlers, middleware, or access the underlying server instance.
//
// Configuration:
//
// The module requires an "httpserver" configuration section with server
// settings including address, ports, TLS configuration, and timeout values.
package httpserver
import (
"context"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"errors"
"fmt"
"math/big"
"net"
"net/http"
"os"
"reflect"
"sync"
"time"
"github.com/GoCodeAlone/modular"
cloudevents "github.com/cloudevents/sdk-go/v2"
)
// ModuleName is the name of this module for registration and dependency resolution.
const ModuleName = "httpserver"
// Error definitions for HTTP server operations.
var (
// ErrServerNotStarted is returned when attempting to stop a server that hasn't been started.
ErrServerNotStarted = errors.New("server not started")
// ErrNoHandler is returned when no HTTP handler is available for the server.
ErrNoHandler = errors.New("no HTTP handler available")
// ErrRouterServiceNotHandler is returned when the router service doesn't implement http.Handler.
ErrRouterServiceNotHandler = errors.New("router service does not implement http.Handler")
// ErrServerStartTimeout is returned when the server fails to start within the timeout period.
ErrServerStartTimeout = errors.New("context cancelled while waiting for server to start")
)
// HTTPServerModule represents the HTTP server module and implements the modular.Module interface.
// It provides a complete HTTP server implementation with TLS support, graceful shutdown,
// and integration with the modular framework's configuration and service systems.
//
// The module manages:
// - HTTP server lifecycle (start, stop, graceful shutdown)
// - TLS certificate management and automatic generation
// - Request routing and handler registration
// - Server configuration and health monitoring
// - Integration with certificate services for automatic HTTPS
// - Event observation and emission for server operations
//
// The module implements the following interfaces:
// - modular.Module: Basic module lifecycle
// - modular.Configurable: Configuration management
// - modular.ServiceAware: Service dependency management
// - modular.Startable: Startup logic
// - modular.Stoppable: Shutdown logic
// - modular.ObservableModule: Event observation and emission
type HTTPServerModule struct {
config *HTTPServerConfig
server *http.Server
app modular.Application
logger modular.Logger
handler http.Handler
started bool
certificateService CertificateService
subject modular.Subject // For event observation (guarded by mu)
draining bool // Set by PreStop to signal drain phase
mu sync.RWMutex
}
// Make sure the HTTPServerModule implements the Module interface
var _ modular.Module = (*HTTPServerModule)(nil)
// NewHTTPServerModule creates a new instance of the HTTP server module.
// The returned module must be registered with the application before use.
//
// Example:
//
// httpModule := httpserver.NewHTTPServerModule()
// app.RegisterModule(httpModule)
func NewHTTPServerModule() modular.Module {
return &HTTPServerModule{}
}
// Name returns the name of the module.
// This name is used for dependency resolution and configuration section lookup.
func (m *HTTPServerModule) Name() string {
return ModuleName
}
// RegisterConfig registers the module's configuration structure.
// The HTTP server module supports comprehensive configuration including:
// - Server address and port settings
// - Timeout configurations (read, write, idle, shutdown)
// - TLS settings and certificate paths
// - Security headers and CORS configuration
//
// Default values are provided for common use cases, but can be
// overridden through configuration files or environment variables.
func (m *HTTPServerModule) RegisterConfig(app modular.Application) error {
// Check if httpserver config is already registered (e.g., by tests)
if _, err := app.GetConfigSection(m.Name()); err == nil {
// Config already registered, skip to avoid overriding
return nil
}
// Register default config only if not already present
defaultConfig := &HTTPServerConfig{
Host: "0.0.0.0",
Port: 8080,
ReadTimeout: 15 * time.Second,
WriteTimeout: 15 * time.Second,
IdleTimeout: 60 * time.Second,
ShutdownTimeout: 30 * time.Second,
}
app.RegisterConfigSection(m.Name(), modular.NewStdConfigProvider(defaultConfig))
return nil
}
// Init initializes the module with the provided application.
// This method loads the configuration, sets up the logger, and prepares
// the HTTP server for startup. It also attempts to resolve optional
// services like certificate management.
//
// Initialization process:
// 1. Load HTTP server configuration
// 2. Set up logging
// 3. Resolve optional certificate service for TLS
// 4. Prepare server instance (actual startup happens in Start)
func (m *HTTPServerModule) Init(app modular.Application) error {
m.app = app
m.logger = app.Logger()
m.logger.Info("Initializing HTTP server module")
// Get the config section
cfg, err := app.GetConfigSection(m.Name())
if err != nil {
return fmt.Errorf("failed to get config section '%s': %w", m.Name(), err)
}
m.config = cfg.GetConfig().(*HTTPServerConfig)
// After configuration is loaded, emit a module-specific config loaded event.
// Only attempt emission if a subject is available; unit tests may not provide one.
hasSubject := m.subject != nil
if !hasSubject {
if _, ok := m.app.(modular.Subject); ok {
hasSubject = true
}
}
if hasSubject {
cfgEvent := modular.NewCloudEvent(EventTypeConfigLoaded, "httpserver-module", map[string]interface{}{
"host": m.config.Host,
"port": m.config.Port,
"http_address": fmt.Sprintf("%s:%d", m.config.Host, m.config.Port),
"read_timeout": m.config.ReadTimeout.String(),
"tls_enabled": m.config.TLS != nil && m.config.TLS.Enabled,
}, nil)
if err := m.EmitEvent(modular.WithSynchronousNotification(context.Background()), cfgEvent); err != nil {
m.logger.Debug("Failed to emit httpserver config loaded event", "error", err)
}
}
return nil
}
// Constructor returns a dependency injection function that initializes the module with
// required services
func (m *HTTPServerModule) Constructor() modular.ModuleConstructor {
return func(_ modular.Application, services map[string]any) (modular.Module, error) {
// Get the router service (which implements http.Handler)
handler, ok := services["router"].(http.Handler)
if !ok {
return nil, fmt.Errorf("%w: %s", ErrRouterServiceNotHandler, "router")
}
// Store the handler for use in Start - wrap with request event middleware
m.handler = m.wrapHandlerWithRequestEvents(handler)
// Check if a certificate service is available, but it's optional
if certService, ok := services["certificate"].(CertificateService); ok {
m.logger.Info("Found certificate service, will use for TLS")
m.certificateService = certService
}
return m, nil
}
}
// Start starts the HTTP server and begins accepting connections.
// This method configures the server with the loaded configuration,
// sets up TLS if enabled, and starts listening for HTTP requests.
//
// The server startup process:
// 1. Validate that a handler has been registered
// 2. Create http.Server instance with configured timeouts
// 3. Set up TLS certificates if HTTPS is enabled
// 4. Start the server in a goroutine
// 5. Handle graceful shutdown on context cancellation
//
// The server will continue running until the context is cancelled
// or Stop() is called explicitly.
func (m *HTTPServerModule) Start(ctx context.Context) error {
if m.handler == nil {
return ErrNoHandler
}
// Create address string from host and port
addr := fmt.Sprintf("%s:%d", m.config.Host, m.config.Port)
// Always ensure the handler is wrapped to emit request events, even if a plain
// handler was set after construction (e.g., in tests). Wrapping multiple times is
// safe functionally, but to avoid duplicate emissions, only wrap if it's not our
// wrapper already. Since we can't reliably detect prior wrapping without adding
// types, we conservatively wrap here to guarantee event emission.
effectiveHandler := m.wrapHandlerWithRequestEvents(m.handler)
// Create server with configured timeouts
m.server = &http.Server{
Addr: addr,
Handler: effectiveHandler,
ReadTimeout: m.config.ReadTimeout,
WriteTimeout: m.config.WriteTimeout,
IdleTimeout: m.config.IdleTimeout,
MaxHeaderBytes: m.config.MaxHeaderBytes,
}
// Start the server in a goroutine
go m.runServer(ctx, addr)
// Test that server is actually listening
if err := m.waitForServerStart(ctx, addr); err != nil {
return err
}
m.started = true
m.logger.Info("HTTP server started successfully", "address", addr)
// Emit server started event synchronously
event := modular.NewCloudEvent(EventTypeServerStarted, "httpserver-service", map[string]interface{}{
"address": addr,
"tls_enabled": m.config.TLS != nil && m.config.TLS.Enabled,
"host": m.config.Host,
"port": m.config.Port,
}, nil)
if emitErr := m.EmitEvent(ctx, event); emitErr != nil {
m.logger.Debug("Failed to emit server started event", "error", emitErr)
}
// Emit TLS configured event if TLS is enabled
m.emitTLSConfiguredEvent(ctx)
return nil
}
// runServer starts the HTTP server with appropriate TLS configuration
func (m *HTTPServerModule) runServer(ctx context.Context, addr string) {
defer func() {
if r := recover(); r != nil {
m.logger.Error("panic recovered in HTTP server", "error", r)
}
}()
m.logger.Info("Starting HTTP server", "address", addr)
var err error
// Start server with or without TLS based on configuration
if m.config.TLS != nil && m.config.TLS.Enabled {
err = m.startTLSServer(ctx)
} else {
err = m.server.ListenAndServe()
}
// If server was shut down gracefully, err will be http.ErrServerClosed
if err != nil && !errors.Is(err, http.ErrServerClosed) {
m.logger.Error("HTTP server error", "error", err)
}
}
// startTLSServer configures and starts the server with TLS
func (m *HTTPServerModule) startTLSServer(ctx context.Context) error {
// Configure TLS
tlsConfig := &tls.Config{
MinVersion: tls.VersionTLS12,
}
// UseService flag takes precedence
if m.config.TLS.UseService {
return m.startWithCertificateService(ctx, tlsConfig)
} else if m.config.TLS.AutoGenerate {
return m.startWithAutoGeneratedCerts(ctx, tlsConfig)
} else {
return m.startWithCertificateFiles(ctx)
}
}
// startWithCertificateService starts server using certificate service
func (m *HTTPServerModule) startWithCertificateService(ctx context.Context, tlsConfig *tls.Config) error {
if m.certificateService != nil {
m.logger.Info("Using certificate service for TLS")
tlsConfig.GetCertificate = m.certificateService.GetCertificate
// Emit TLS enabled event SYNCHRONOUSLY
tlsEvent := modular.NewCloudEvent(EventTypeTLSEnabled, "httpserver-service", map[string]interface{}{
"method": "certificate_service",
}, nil)
if emitErr := m.EmitEvent(ctx, tlsEvent); emitErr != nil {
m.logger.Debug("Failed to emit TLS enabled event", "error", emitErr)
}
m.server.TLSConfig = tlsConfig
if err := m.server.ListenAndServeTLS("", ""); err != nil {
return fmt.Errorf("failed to start HTTPS server with certificate service: %w", err)
}
return nil
}
// Fall back to auto-generated certificates if UseService is true but no service is available
m.logger.Warn("No certificate service available, falling back to auto-generated certificates")
if len(m.config.TLS.Domains) == 0 {
m.config.TLS.Domains = []string{"localhost"}
}
return m.startWithAutoGeneratedCerts(ctx, tlsConfig)
}
// startWithAutoGeneratedCerts starts server with auto-generated certificates
func (m *HTTPServerModule) startWithAutoGeneratedCerts(ctx context.Context, tlsConfig *tls.Config) error {
m.logger.Info("Auto-generating self-signed certificates", "domains", m.config.TLS.Domains)
// Emit TLS enabled event SYNCHRONOUSLY before starting server
tlsEvent := modular.NewCloudEvent(EventTypeTLSEnabled, "httpserver-service", map[string]interface{}{
"method": "auto_generate",
"domains": m.config.TLS.Domains,
}, nil)
if emitErr := m.EmitEvent(ctx, tlsEvent); emitErr != nil {
m.logger.Debug("Failed to emit TLS auto-generate event", "error", emitErr)
}
cert, key, err := m.generateSelfSignedCertificate(m.config.TLS.Domains)
if err != nil {
m.logger.Error("Failed to generate self-signed certificate", "error", err)
if err := m.server.ListenAndServe(); err != nil {
return fmt.Errorf("failed to start HTTP server after certificate generation failure: %w", err)
}
return nil
}
m.server.TLSConfig = tlsConfig
if err := m.server.ListenAndServeTLS(cert, key); err != nil {
return fmt.Errorf("failed to start HTTPS server with auto-generated certificates: %w", err)
}
return nil
}
// startWithCertificateFiles starts server using provided certificate files
func (m *HTTPServerModule) startWithCertificateFiles(ctx context.Context) error {
m.logger.Info("Using TLS configuration", "cert", m.config.TLS.CertFile, "key", m.config.TLS.KeyFile)
// Emit TLS enabled event SYNCHRONOUSLY
tlsEvent := modular.NewCloudEvent(EventTypeTLSEnabled, "httpserver-service", map[string]interface{}{
"method": "certificate_files",
"cert_file": m.config.TLS.CertFile,
"key_file": m.config.TLS.KeyFile,
}, nil)
if emitErr := m.EmitEvent(ctx, tlsEvent); emitErr != nil {
m.logger.Debug("Failed to emit TLS configured event", "error", emitErr)
}
if err := m.server.ListenAndServeTLS(m.config.TLS.CertFile, m.config.TLS.KeyFile); err != nil {
return fmt.Errorf("failed to start HTTPS server with certificate files: %w", err)
}
return nil
}
// waitForServerStart waits for the server to start accepting connections
func (m *HTTPServerModule) waitForServerStart(ctx context.Context, addr string) error {
timeout := time.Second
if deadline, ok := ctx.Deadline(); ok {
timeout = time.Until(deadline)
}
checkCtx, cancel := context.WithTimeout(ctx, timeout)
defer cancel()
check := func() error {
var dialer net.Dialer
conn, err := dialer.DialContext(checkCtx, "tcp", addr)
if err != nil {
return fmt.Errorf("dialing server: %w", err)
}
if closeErr := conn.Close(); closeErr != nil {
m.logger.Warn("Failed to close connection", "error", closeErr)
}
return nil
}
// Try to connect to the server with retries
ticker := time.NewTicker(100 * time.Millisecond)
defer ticker.Stop()
startTime := time.Now()
for {
err := check()
if err == nil {
break // Successfully connected
}
// Check if the timeout has expired
if time.Since(startTime) > timeout {
return fmt.Errorf("failed to start HTTP server within timeout: %w", err)
}
// Wait before retrying
select {
case <-checkCtx.Done():
return ErrServerStartTimeout
case <-ticker.C:
}
}
return nil
}
// emitTLSConfiguredEvent emits TLS configured event if TLS is enabled
func (m *HTTPServerModule) emitTLSConfiguredEvent(ctx context.Context) {
if m.config.TLS == nil || !m.config.TLS.Enabled {
return
}
var tlsMethod string
if m.certificateService != nil && m.config.TLS.UseService {
tlsMethod = "certificate_service"
} else if m.config.TLS.AutoGenerate {
tlsMethod = "auto_generate"
} else {
tlsMethod = "certificate_files"
}
tlsConfiguredEvent := modular.NewCloudEvent(EventTypeTLSConfigured, "httpserver-service", map[string]interface{}{
"method": tlsMethod,
"https_port": m.config.Port,
"cert_method": tlsMethod,
}, nil)
if emitErr := m.EmitEvent(ctx, tlsConfiguredEvent); emitErr != nil {
m.logger.Debug("Failed to emit TLS configured event", "error", emitErr)
}
}
// Stop stops the HTTP server gracefully.
// This method initiates a graceful shutdown of the HTTP server,
// allowing existing connections to finish processing before closing.
//
// The shutdown process:
// 1. Check if server is running
// 2. Create shutdown context with configured timeout
// 3. Call server.Shutdown() to stop accepting new connections
// 4. Wait for existing connections to complete or timeout
// 5. Mark server as stopped
//
// If the shutdown timeout is exceeded, the server will be forcefully closed.
func (m *HTTPServerModule) Stop(ctx context.Context) error {
if m.server == nil || !m.started {
return ErrServerNotStarted
}
m.logger.Info("Stopping HTTP server", "timeout", m.config.ShutdownTimeout)
// Create a context with timeout for shutdown
shutdownCtx, cancel := context.WithTimeout(
ctx,
m.config.ShutdownTimeout,
)
defer cancel()
// Shutdown the server gracefully
err := m.server.Shutdown(shutdownCtx)
if err != nil {
return fmt.Errorf("error shutting down HTTP server: %w", err)
}
m.started = false
m.logger.Info("HTTP server stopped successfully")
// Removed synthetic request event emission: tests no longer rely on placeholder
// events when no real traffic occurred. If needed in the future, reintroduce
// behind a test-only build tag or explicit configuration flag.
// Emit server stopped event synchronously
event := modular.NewCloudEvent(EventTypeServerStopped, "httpserver-service", map[string]interface{}{
"host": m.config.Host,
"port": m.config.Port,
}, nil)
if emitErr := m.EmitEvent(ctx, event); emitErr != nil {
m.logger.Debug("Failed to emit server stopped event", "error", emitErr)
}
return nil
}
// ProvidesServices returns the services provided by this module
func (m *HTTPServerModule) ProvidesServices() []modular.ServiceProvider {
return []modular.ServiceProvider{
{
Name: "httpserver",
Description: "HTTP server module for handling HTTP requests and providing web services",
Instance: m,
},
}
}
// RequiresServices returns the services required by this module
func (m *HTTPServerModule) RequiresServices() []modular.ServiceDependency {
deps := []modular.ServiceDependency{
{
Name: "router",
Required: true,
MatchByInterface: true,
SatisfiesInterface: reflect.TypeOf((*http.Handler)(nil)).Elem(),
},
}
// Add optional certificate service dependency
deps = append(deps, modular.ServiceDependency{
Name: "certificate",
Required: false, // Optional dependency
MatchByInterface: true,
SatisfiesInterface: reflect.TypeOf((*CertificateService)(nil)).Elem(),
})
return deps
}
// generateSelfSignedCertificate generates a self-signed certificate for the given domains.
// Returns the paths to the generated certificate and key files.
func (m *HTTPServerModule) generateSelfSignedCertificate(domains []string) (string, string, error) {
// Generate a new private key
privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
return "", "", fmt.Errorf("failed to generate private key: %w", err)
}
// Create certificate template
serialNumber, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
if err != nil {
return "", "", fmt.Errorf("failed to generate serial number: %w", err)
}
template := x509.Certificate{
SerialNumber: serialNumber,
Subject: pkix.Name{
Organization: []string{"Self-Signed Certificate"},
CommonName: domains[0], // Use the first domain as the common name
},
NotBefore: time.Now(),
NotAfter: time.Now().Add(365 * 24 * time.Hour), // Valid for 1 year
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
}
// Add all domains as SANs
for _, domain := range domains {
if ip := net.ParseIP(domain); ip != nil {
template.IPAddresses = append(template.IPAddresses, ip)
} else {
template.DNSNames = append(template.DNSNames, domain)
}
}
// Add localhost and 127.0.0.1 to allow local testing
template.DNSNames = append(template.DNSNames, "localhost")
template.IPAddresses = append(template.IPAddresses, net.ParseIP("127.0.0.1"))
template.IPAddresses = append(template.IPAddresses, net.ParseIP("::1"))
// Create certificate from template and sign it with the private key
certDER, err := x509.CreateCertificate(rand.Reader, &template, &template, &privateKey.PublicKey, privateKey)
if err != nil {
return "", "", fmt.Errorf("failed to create certificate: %w", err)
}
// Convert DER certificate to PEM format
certPEM := string(pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certDER}))
// Convert private key to PEM format
keyBytes, err := x509.MarshalPKCS8PrivateKey(privateKey)
if err != nil {
return "", "", fmt.Errorf("failed to marshal private key: %w", err)
}
keyPEM := string(pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: keyBytes}))
// Create temporary files for certificate and key
certFile, err := m.createTempFile("cert*.pem", certPEM)
if err != nil {
return "", "", fmt.Errorf("failed to create certificate file: %w", err)
}
keyFile, err := m.createTempFile("key*.pem", keyPEM)
if err != nil {
return "", "", fmt.Errorf("failed to create key file: %w", err)
}
return certFile, keyFile, nil
}
// createTempFile creates a temporary file with the given content
func (m *HTTPServerModule) createTempFile(pattern, content string) (string, error) {
tmpFile, err := os.CreateTemp("", pattern)
if err != nil {
return "", fmt.Errorf("creating temp file: %w", err)
}
defer func() {
if closeErr := tmpFile.Close(); closeErr != nil {
m.logger.Warn("Failed to close temp file", "error", closeErr)
}
}()
if _, err := tmpFile.WriteString(content); err != nil {
return "", fmt.Errorf("writing to temp file: %w", err)
}
return tmpFile.Name(), nil
}
// RegisterObservers implements the ObservableModule interface.
// This allows the httpserver module to register as an observer for events it's interested in.
func (m *HTTPServerModule) RegisterObservers(subject modular.Subject) error {
m.mu.Lock()
m.subject = subject
m.mu.Unlock()
return nil
}
// EmitEvent implements the ObservableModule interface.
// This allows the httpserver module to emit events to registered observers.
func (m *HTTPServerModule) EmitEvent(ctx context.Context, event cloudevents.Event) error {
// Acquire subject snapshot under read lock
m.mu.RLock()
subject := m.subject
m.mu.RUnlock()
// Fallback to app subject only if module subject not set
if subject == nil && m.app != nil {
if s, ok := m.app.(modular.Subject); ok {
subject = s
}
}
if subject == nil {
return ErrNoSubjectForEventEmission
}
// Synchronous for request lifecycle events
if event.Type() == EventTypeRequestReceived || event.Type() == EventTypeRequestHandled {
ctx = modular.WithSynchronousNotification(ctx)
if err := subject.NotifyObservers(ctx, event); err != nil {
return fmt.Errorf("failed to notify observers for event %s: %w", event.Type(), err)
}
return nil
}
go func(s modular.Subject, e cloudevents.Event) {
defer func() {
if r := recover(); r != nil {
if m.logger != nil {
m.logger.Error("observer panic", "error", r)
}
}
}()
if err := s.NotifyObservers(ctx, e); err != nil && m.logger != nil {
m.logger.Debug("Failed to notify observers", "error", err, "event_type", e.Type())
}
}(subject, event)
return nil
}
// wrapHandlerWithRequestEvents wraps the HTTP handler to emit request events
func (m *HTTPServerModule) wrapHandlerWithRequestEvents(handler http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Request lifecycle events are emitted for each real request
// Emit request received event SYNCHRONOUSLY to ensure immediate emission
requestReceivedEvent := modular.NewCloudEvent(EventTypeRequestReceived, "httpserver-service", map[string]interface{}{
"method": r.Method,
"url": r.URL.String(),
"remote_addr": r.RemoteAddr,
"user_agent": r.UserAgent(),
}, nil)
// Request events should be delivered synchronously; set hint via a background context to avoid cancellation
if emitErr := m.EmitEvent(modular.WithSynchronousNotification(r.Context()), requestReceivedEvent); emitErr != nil {
if m.logger != nil {
m.logger.Debug("Failed to emit request received event", "error", emitErr)
}
}
// Wrap response writer to capture status code
// Default to 0 (unset) to distinguish between explicit and implicit status codes
wrappedWriter := &responseWriter{ResponseWriter: w, statusCode: 0}
// Call the original handler
handler.ServeHTTP(wrappedWriter, r)
// Emit request handled event SYNCHRONOUSLY to ensure immediate emission
// Use the actual status code if set, otherwise default to 200 (HTTP OK)
statusCode := wrappedWriter.statusCode
if statusCode == 0 {
statusCode = http.StatusOK // Default for successful responses when not explicitly set
}
requestHandledEvent := modular.NewCloudEvent(EventTypeRequestHandled, "httpserver-service", map[string]interface{}{
"method": r.Method,
"url": r.URL.String(),
"status_code": statusCode,
"remote_addr": r.RemoteAddr,
}, nil)
// Request events should be delivered synchronously; set hint via a background context to avoid cancellation
if emitErr := m.EmitEvent(modular.WithSynchronousNotification(r.Context()), requestHandledEvent); emitErr != nil {
if m.logger != nil {
m.logger.Debug("Failed to emit request handled event", "error", emitErr)
}
}
})
}
// responseWriter wraps http.ResponseWriter to capture status code
type responseWriter struct {
http.ResponseWriter
statusCode int
headerWritten bool // Track if WriteHeader has been called
}
func (rw *responseWriter) WriteHeader(code int) {
// Prevent multiple calls to WriteHeader as per HTTP specification
if rw.headerWritten {
return
}
rw.statusCode = code
rw.headerWritten = true
rw.ResponseWriter.WriteHeader(code)
}
func (rw *responseWriter) Write(data []byte) (int, error) {
// If WriteHeader hasn't been called yet, it will be called implicitly with 200
if !rw.headerWritten {
rw.WriteHeader(http.StatusOK)
}
n, err := rw.ResponseWriter.Write(data)
if err != nil {
return n, fmt.Errorf("failed to write HTTP response: %w", err)
}
return n, nil
}
// GetRegisteredEventTypes implements the ObservableModule interface.
// Returns all event types that this httpserver module can emit.
func (m *HTTPServerModule) GetRegisteredEventTypes() []string {
return []string{
EventTypeServerStarted,
EventTypeServerStopped,
EventTypeRequestReceived,
EventTypeRequestHandled,
EventTypeTLSEnabled,
EventTypeTLSConfigured,
EventTypeConfigLoaded,
}
}