machine config: make write atomic

As indicated in #21849, loading the machine config can flake/fail with an EOF JSON error indicating an incomplete file. Address the issue by atomically writing the config. This way, it is not possible to load an incomplete or partially written file. The lock can be acquired later on to sync state. [NO NEW TESTS NEEDED] as it's a hard-to-hit race. Fixes: #21849 Signed-off-by: Valentin Rothberg <[email protected]>
containers · Feb 28, 2024 · f8abd7f · f8abd7f
1 parent 9d17043
commit f8abd7f
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/pkg/machine/vmconfigs/machine.go b/pkg/machine/vmconfigs/machine.go
@@ -16,6 +16,7 @@ import (
 	"github.com/containers/podman/v5/pkg/machine/define"
 	"github.com/containers/podman/v5/pkg/machine/lock"
 	"github.com/containers/podman/v5/utils"
+	"github.com/containers/storage/pkg/ioutils"
 	"github.com/sirupsen/logrus"
 )
 
@@ -133,7 +134,7 @@ func (mc *MachineConfig) write() error {
 		return err
 	}
 	logrus.Debugf("writing configuration file %q", mc.configPath.Path)
-	return os.WriteFile(mc.configPath.GetPath(), b, define.DefaultFilePerm)
+	return ioutils.AtomicWriteFile(mc.configPath.GetPath(), b, define.DefaultFilePerm)
 }
 
 func (mc *MachineConfig) SetRootful(rootful bool) error {