Public IP loop, fixes #186

- Uses common http client with 15 seconds timeout
- Repeats on fail after 5 seconds sleep time

internal/publicip/loop.go

@@ -0,0 +1,73 @@
+package publicip
+
+import (
+	"context"
+	"time"
+
+	"github.com/qdm12/golibs/files"
+	"github.com/qdm12/golibs/logging"
+	"github.com/qdm12/golibs/network"
+	"github.com/qdm12/private-internet-access-docker/internal/models"
+)
+
+type Looper interface {
+	Run(ctx context.Context, restart <-chan struct{})
+}
+
+type looper struct {
+	getter           IPGetter
+	logger           logging.Logger
+	fileManager      files.FileManager
+	ipStatusFilepath models.Filepath
+	uid              int
+	gid              int
+}
+
+func NewLooper(client network.Client, logger logging.Logger, fileManager files.FileManager,
+	ipStatusFilepath models.Filepath, uid, gid int) Looper {
+	return &looper{
+		getter:           NewIPGetter(client),
+		logger:           logger.WithPrefix("ip getter: "),
+		fileManager:      fileManager,
+		ipStatusFilepath: ipStatusFilepath,
+		uid:              uid,
+		gid:              gid,
+	}
+}
+
+func (l *looper) logAndWait(err error) {
+	l.logger.Error(err)
+	l.logger.Info("retrying in 5 seconds")
+	time.Sleep(5 * time.Second)
+}
+
+func (l *looper) Run(ctx context.Context, restart <-chan struct{}) {
+	select {
+	case <-restart:
+	case <-ctx.Done():
+		return
+	}
+	for {
+		ip, err := l.getter.Get()
+		if err != nil {
+			l.logAndWait(err)
+			continue
+		}
+		l.logger.Info("Public IP address is %s", ip)
+		err = l.fileManager.WriteLinesToFile(
+			string(l.ipStatusFilepath),
+			[]string{ip.String()},
+			files.Ownership(l.uid, l.gid),
+			files.Permissions(0600))
+		if err != nil {
+			l.logAndWait(err)
+			continue
+		}
+		select {
+		case <-restart: // triggered restart
+		case <-ctx.Done():
+			l.logger.Warn("context canceled: exiting loop")
+			return
+		}
+	}
+}