feat(embed): make authelia embedable (#8841)

This adds a highly experimental option for developers looking to embed Authelia within another go binary.

Closes #5803

Signed-off-by: James Elliott <james-d-elliott@users.noreply.github.com>

1 files changed, 81 insertions, 0 deletions

diff --git a/internal/service/signal.go b/internal/service/signal.go
new file mode 100644
index 000000000..b6445a792
--- /dev/null
+++ b/internal/service/signal.go
@@ -0,0 +1,81 @@
+package service
+
+import (
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/sirupsen/logrus"
+
+	"github.com/authelia/authelia/v4/internal/logging"
+)
+
+func ProvisionLoggingSignal(ctx Context) (service Provider, err error) {
+	config := ctx.GetConfiguration()
+
+	if config == nil || len(config.Log.FilePath) == 0 {
+		return nil, nil
+	}
+
+	return &Signal{
+		name:    "log-reload",
+		signals: []os.Signal{syscall.SIGHUP},
+		action:  logging.Reopen,
+		log:     ctx.GetLogger().WithFields(map[string]any{logFieldService: serviceTypeSignal, serviceTypeSignal: "log-reload"}),
+	}, nil
+}
+
+// Signal is a Service which performs actions on signals.
+type Signal struct {
+	name    string
+	signals []os.Signal
+	action  func() (err error)
+	log     *logrus.Entry
+
+	notify chan os.Signal
+	quit   chan struct{}
+}
+
+// ServiceType returns the service type for this service, which is always 'server'.
+func (service *Signal) ServiceType() string {
+	return serviceTypeSignal
+}
+
+// ServiceName returns the individual name for this service.
+func (service *Signal) ServiceName() string {
+	return service.name
+}
+
+// Run the ServerService.
+func (service *Signal) Run() (err error) {
+	service.quit = make(chan struct{})
+
+	service.notify = make(chan os.Signal, 1)
+
+	signal.Notify(service.notify, service.signals...)
+
+	for {
+		select {
+		case s := <-service.notify:
+			if err = service.action(); err != nil {
+				service.log.WithError(err).Error("Error occurred executing service action.")
+			} else {
+				service.log.WithFields(map[string]any{"signal-received": s.String()}).Debug("Successfully executed service action.")
+			}
+		case <-service.quit:
+			return
+		}
+	}
+}
+
+// Shutdown the ServerService.
+func (service *Signal) Shutdown() {
+	signal.Stop(service.notify)
+
+	service.quit <- struct{}{}
+}
+
+// Log returns the *logrus.Entry of the ServerService.
+func (service *Signal) Log() *logrus.Entry {
+	return service.log
+}