From 309c49413cec5576d0cb4b45aefff0a371eb1e79 Mon Sep 17 00:00:00 2001
From: Justin Chadwell <me@jedevc.com>
Date: Tue, 12 Jul 2022 13:10:05 +0100
Subject: [PATCH 1/2] buildx: log errors in initializing builders

Previously, errors within the driver config would not be reported to the
user until they tried to use the driver, even though they are easily
accessible from the node group info.

This patch reports these errors (but will not fail because of them,
since the data is already saved) - this should help improve
debuggability of some of the more complex drivers, and prevent error
messages being suppressed.

Signed-off-by: Justin Chadwell <me@jedevc.com>
---
 commands/create.go | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/commands/create.go b/commands/create.go
index 2a9c1296a08..9238551c949 100644
--- a/commands/create.go
+++ b/commands/create.go
@@ -242,6 +242,11 @@ func runCreate(dockerCli command.Cli, in createOptions, args []string) error {
 	if err = loadNodeGroupData(timeoutCtx, dockerCli, ngi); err != nil {
 		return err
 	}
+	for _, info := range ngi.drivers {
+		if err := info.di.Err; err != nil {
+			logrus.Errorf("failed to initialize builder %s (%s): %s", ng.Name, info.di.Name, err)
+		}
+	}
 
 	if in.bootstrap {
 		if _, err = boot(ctx, ngi); err != nil {

From 86825a95ce655383f9eec8b4d7637ccc6ad5a2dd Mon Sep 17 00:00:00 2001
From: Justin Chadwell <me@jedevc.com>
Date: Wed, 27 Jul 2022 11:48:52 +0100
Subject: [PATCH 2/2] buildx: rollback configuration if create fails

This builds on the added warnings from initialized builders, now
erroring the command, and additionally attempting to revert to the
previous configuration.

To preserve the previous configuration, we add a deep Copy() function to
the NodeGroup and Node so that we can easily restore it later if we
encounter a failure.

Signed-off-by: Justin Chadwell <me@jedevc.com>
---
 commands/create.go | 37 ++++++++++++++++++++++++++-----------
 store/nodegroup.go | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 11 deletions(-)

diff --git a/commands/create.go b/commands/create.go
index 9238551c949..87b53a806be 100644
--- a/commands/create.go
+++ b/commands/create.go
@@ -134,6 +134,11 @@ func runCreate(dockerCli command.Cli, in createOptions, args []string) error {
 		}
 	}
 
+	ngOriginal := ng
+	if ngOriginal != nil {
+		ngOriginal = ngOriginal.Copy()
+	}
+
 	if ng == nil {
 		ng = &store.NodeGroup{
 			Name: name,
@@ -224,16 +229,6 @@ func runCreate(dockerCli command.Cli, in createOptions, args []string) error {
 		return err
 	}
 
-	if in.use && ep != "" {
-		current, err := storeutil.GetCurrentEndpoint(dockerCli)
-		if err != nil {
-			return err
-		}
-		if err := txn.SetCurrent(current, ng.Name, false, false); err != nil {
-			return err
-		}
-	}
-
 	ngi := &nginfo{ng: ng}
 
 	timeoutCtx, cancel := context.WithTimeout(ctx, 20*time.Second)
@@ -244,7 +239,27 @@ func runCreate(dockerCli command.Cli, in createOptions, args []string) error {
 	}
 	for _, info := range ngi.drivers {
 		if err := info.di.Err; err != nil {
-			logrus.Errorf("failed to initialize builder %s (%s): %s", ng.Name, info.di.Name, err)
+			err := errors.Errorf("failed to initialize builder %s (%s): %s", ng.Name, info.di.Name, err)
+			var err2 error
+			if ngOriginal == nil {
+				err2 = txn.Remove(ng.Name)
+			} else {
+				err2 = txn.Save(ngOriginal)
+			}
+			if err2 != nil {
+				logrus.Warnf("Could not rollback to previous state: %s", err2)
+			}
+			return err
+		}
+	}
+
+	if in.use && ep != "" {
+		current, err := storeutil.GetCurrentEndpoint(dockerCli)
+		if err != nil {
+			return err
+		}
+		if err := txn.SetCurrent(current, ng.Name, false, false); err != nil {
+			return err
 		}
 	}
 
diff --git a/store/nodegroup.go b/store/nodegroup.go
index c9f97a67228..b6288e0981a 100644
--- a/store/nodegroup.go
+++ b/store/nodegroup.go
@@ -110,6 +110,44 @@ func (ng *NodeGroup) Update(name, endpoint string, platforms []string, endpoints
 	return nil
 }
 
+func (ng *NodeGroup) Copy() *NodeGroup {
+	nodes := make([]Node, len(ng.Nodes))
+	for i, node := range ng.Nodes {
+		nodes[i] = *node.Copy()
+	}
+	return &NodeGroup{
+		Name:    ng.Name,
+		Driver:  ng.Driver,
+		Nodes:   nodes,
+		Dynamic: ng.Dynamic,
+	}
+}
+
+func (n *Node) Copy() *Node {
+	platforms := []specs.Platform{}
+	copy(platforms, n.Platforms)
+	flags := []string{}
+	copy(flags, n.Flags)
+	driverOpts := map[string]string{}
+	for k, v := range n.DriverOpts {
+		driverOpts[k] = v
+	}
+	files := map[string][]byte{}
+	for k, v := range n.Files {
+		vv := []byte{}
+		copy(vv, v)
+		files[k] = vv
+	}
+	return &Node{
+		Name:       n.Name,
+		Endpoint:   n.Endpoint,
+		Platforms:  platforms,
+		Flags:      flags,
+		DriverOpts: driverOpts,
+		Files:      files,
+	}
+}
+
 func (ng *NodeGroup) validateDuplicates(ep string, idx int) error {
 	i := 0
 	for _, n := range ng.Nodes {