From c1f086867d363aea5ed4ef12c71e8c81067108cb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julian=20T=C3=B6lle?= <julian.toelle@hetzner-cloud.de>
Date: Fri, 9 May 2025 15:55:06 +0200
Subject: [PATCH] fix: timeout while waiting for SSH to become available

In #68 I reduced the general limits for the backoff, thinking that it
would speed up the upload on average because it was retrying faster. But
because it was retrying faster, the 10 available retries were used up
before SSH became available.

The new 100 retries match the 3 minutes of total timeout that the
previous solution had, and should fix all issues.

In addition I discovered that my implementation in
`hcloudimages/backoff.ExponentialBackoffWithLimit` has a bug where the
calculated offset could overflow before the limit was applied, resulting
in negative durations. I did not fix the issue because `hcloud-go`
provides such a method natively nowadays. Instead I marked the method as
deprected, to be removed in a later release.
---
 cmd/root.go                            | 3 +--
 hcloudimages/backoff/backoff.go        | 4 ++++
 hcloudimages/client.go                 | 2 +-
 hcloudimages/internal/control/retry.go | 5 +++--
 4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/cmd/root.go b/cmd/root.go
index 86cfe89..98a25d3 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -9,7 +9,6 @@ import (
 	"github.com/spf13/cobra"
 
 	"github.com/apricote/hcloud-upload-image/hcloudimages"
-	"github.com/apricote/hcloud-upload-image/hcloudimages/backoff"
 	"github.com/apricote/hcloud-upload-image/hcloudimages/contextlogger"
 	"github.com/apricote/hcloud-upload-image/internal/ui"
 	"github.com/apricote/hcloud-upload-image/internal/version"
@@ -89,7 +88,7 @@ func initClient(cmd *cobra.Command, _ []string) {
 	opts := []hcloud.ClientOption{
 		hcloud.WithToken(os.Getenv("HCLOUD_TOKEN")),
 		hcloud.WithApplication("hcloud-upload-image", version.Version),
-		hcloud.WithPollOpts(hcloud.PollOpts{BackoffFunc: backoff.ExponentialBackoffWithLimit(2, 1*time.Second, 30*time.Second)}),
+		hcloud.WithPollOpts(hcloud.PollOpts{BackoffFunc: hcloud.ExponentialBackoffWithOpts(hcloud.ExponentialBackoffOpts{Multiplier: 2, Base: 1 * time.Second, Cap: 30 * time.Second})}),
 	}
 
 	if os.Getenv("HCLOUD_DEBUG") != "" || verbose >= 2 {
diff --git a/hcloudimages/backoff/backoff.go b/hcloudimages/backoff/backoff.go
index 310312a..346fb8f 100644
--- a/hcloudimages/backoff/backoff.go
+++ b/hcloudimages/backoff/backoff.go
@@ -16,6 +16,10 @@ import (
 // It uses the formula:
 //
 //	min(b^retries * d, limit)
+//
+// This function has a known overflow issue and should not be used anymore.
+//
+// Deprecated: Use BackoffFuncWithOpts from github.com/hetznercloud/hcloud-go/v2/hcloud instead.
 func ExponentialBackoffWithLimit(b float64, d time.Duration, limit time.Duration) hcloud.BackoffFunc {
 	return func(retries int) time.Duration {
 		current := time.Duration(math.Pow(b, float64(retries))) * d
diff --git a/hcloudimages/client.go b/hcloudimages/client.go
index 62e218a..c30cef9 100644
--- a/hcloudimages/client.go
+++ b/hcloudimages/client.go
@@ -316,7 +316,7 @@ func (s *Client) Upload(ctx context.Context, options UploadOptions) (*hcloud.Ima
 
 	err = control.Retry(
 		contextlogger.New(ctx, logger.With("operation", "ssh")),
-		10,
+		100, // ~ 3 minutes
 		func() error {
 			var err error
 			logger.DebugContext(ctx, "trying to connect to server", "ip", server.PublicNet.IPv4.IP)
diff --git a/hcloudimages/internal/control/retry.go b/hcloudimages/internal/control/retry.go
index eb56721..44cfe55 100644
--- a/hcloudimages/internal/control/retry.go
+++ b/hcloudimages/internal/control/retry.go
@@ -8,7 +8,8 @@ import (
 	"context"
 	"time"
 
-	"github.com/apricote/hcloud-upload-image/hcloudimages/backoff"
+	"github.com/hetznercloud/hcloud-go/v2/hcloud"
+	
 	"github.com/apricote/hcloud-upload-image/hcloudimages/contextlogger"
 )
 
@@ -18,7 +19,7 @@ func Retry(ctx context.Context, maxTries int, f func() error) error {
 
 	var err error
 
-	backoffFunc := backoff.ExponentialBackoffWithLimit(2, 200*time.Millisecond, 2*time.Second)
+	backoffFunc := hcloud.ExponentialBackoffWithOpts(hcloud.ExponentialBackoffOpts{Multiplier: 2, Base: 200 * time.Millisecond, Cap: 2 * time.Second})
 
 	for try := 0; try < maxTries; try++ {
 		if ctx.Err() != nil {