feat: log output

util/contextlogger/context.go

@@ -0,0 +1,24 @@
+package contextlogger
+
+import (
+	"context"
+	"log/slog"
+)
+
+type key int
+
+var loggerKey key
+
+func New(ctx context.Context, logger *slog.Logger) context.Context {
+	return context.WithValue(ctx, loggerKey, logger)
+}
+
+func From(ctx context.Context) *slog.Logger {
+	if ctxLogger := ctx.Value(loggerKey); ctxLogger != nil {
+		if logger, ok := ctxLogger.(*slog.Logger); ok {
+			return logger
+		}
+	}
+
+	return slog.New(discardHandler{})
+}

util/contextlogger/discard.go

@@ -0,0 +1,15 @@
+package contextlogger
+
+import (
+	"context"
+	"log/slog"
+)
+
+// discardHandler is a [slog.Handler] that just discards any input. It is a safe default if any library
+// method does not get passed a logger through the context.
+type discardHandler struct{}
+
+func (discardHandler) Enabled(_ context.Context, _ slog.Level) bool  { return false }
+func (discardHandler) Handle(_ context.Context, _ slog.Record) error { return nil }
+func (d discardHandler) WithAttrs(_ []slog.Attr) slog.Handler        { return d }
+func (d discardHandler) WithGroup(_ string) slog.Handler             { return d }

util/control/retry.go

@@ -7,6 +7,8 @@ import (
 	"time"
 
 	"github.com/hetznercloud/hcloud-go/v2/hcloud"
+
+	"github.com/apricote/hcloud-upload-image/util/contextlogger"
 )
 
 // From https://github.com/hetznercloud/terraform-provider-hcloud/blob/v1.46.1/internal/control/retry.go
@@ -57,6 +59,8 @@ func AbortRetry(err error) error {
 
 // Retry executes f at most maxTries times.
 func Retry(ctx context.Context, maxTries int, f func() error) error {
+	logger := contextlogger.From(ctx)
+
 	var err error
 
 	backoff := ExponentialBackoffWithLimit(2, 1*time.Second, 30*time.Second)
@@ -74,6 +78,7 @@ func Retry(ctx context.Context, maxTries int, f func() error) error {
 		}
 		if err != nil {
 			sleep := backoff(try)
+			logger.DebugContext(ctx, "operation failed, waiting before trying again", "try", try, "backoff", sleep)
 			time.Sleep(sleep)
 			continue
 		}

util/randomid/randomid.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 )
 
+// From https://gitlab.com/hetznercloud/fleeting-plugin-hetzner/-/blob/0f60204582289c243599f8ca0f5be4822789131d/internal/utils/random.go
+
 func Generate() (string, error) {
 	b := make([]byte, 4)
 	_, err := rand.Read(b)

util/sshkey/ssh_key.go

@@ -7,6 +7,8 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
+// From https://gitlab.com/hetznercloud/fleeting-plugin-hetzner/-/blob/0f60204582289c243599f8ca0f5be4822789131d/internal/utils/ssh_key.go
+
 func GenerateKeyPair() ([]byte, []byte, error) {
 	pub, priv, err := ed25519.GenerateKey(nil)
 	if err != nil {