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MCO-1976: [Dev] Fix RHEL9-specific MCD Logic for RHEL10/CentOS10 Compatibility #5415

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Merged
merged 1 commit into from
Nov 20, 2025
Merged

MCO-1976: [Dev] Fix RHEL9-specific MCD Logic for RHEL10/CentOS10 Compatibility #5415

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13 changes: 11 additions & 2 deletions pkg/daemon/daemon.go
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Original file line number Diff line number Diff line change
Expand Up @@ -535,10 +535,19 @@ func ReexecuteForTargetRoot(target string) error {
if sourceOsVersion.IsLikeRHEL() && targetOsVersion.IsLikeRHEL() {
sourceMajor := sourceOsVersion.BaseVersionMajor()
targetMajor := targetOsVersion.BaseVersionMajor()
if sourceMajor == "9" && targetMajor == "8" {

// When container is newer than target, use target-compatible binary
switch {
case sourceMajor == "10" && targetMajor == "9":
sourceBinarySuffix = ".rhel9"
klog.Info("container is rhel10, target is rhel9")
case sourceMajor == "10" && targetMajor == "8":
sourceBinarySuffix = ".rhel8"
klog.Info("container is rhel10, target is rhel8")
case sourceMajor == "9" && targetMajor == "8":
Comment on lines -538 to +547
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@pablintino pablintino Nov 20, 2025

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Just my 2 cents, but I don't think continuing with version-specific conditionals is the right direction. This piece of code will need a revisit each time there's a new major, like now.
WDYT about something like this?

diff --git a/pkg/daemon/daemon.go b/pkg/daemon/daemon.go
index e990021ed..01170f701 100644
--- a/pkg/daemon/daemon.go
+++ b/pkg/daemon/daemon.go
@@ -14,7 +14,9 @@ import (
        "os/exec"
        "os/signal"
        "path/filepath"
+       "regexp"
        "slices"
+       "strconv"
        "strings"
        "sync"
        "syscall"
@@ -531,20 +533,34 @@ func ReexecuteForTargetRoot(target string) error {
                return fmt.Errorf("failed to get target OS: %w", err)
        }
 
-       var sourceBinarySuffix string
+       sourceBinary := "/usr/bin/machine-config-daemon"
        if sourceOsVersion.IsLikeRHEL() && targetOsVersion.IsLikeRHEL() {
-               sourceMajor := sourceOsVersion.BaseVersionMajor()
-               targetMajor := targetOsVersion.BaseVersionMajor()
-               if sourceMajor == "9" && targetMajor == "8" {
-                       sourceBinarySuffix = ".rhel8"
-                       klog.Info("container is rhel9, target is rhel8")
+               sourceVersion, err := strconv.Atoi(sourceOsVersion.BaseVersionMajor())
+               if err != nil {
+                       return fmt.Errorf("failed to convert source major version: %w", err)
+               }
+               targetVersion, err := strconv.Atoi(targetOsVersion.BaseVersionMajor())
+               if err != nil {
+                       return fmt.Errorf("failed to convert target major version: %w", err)
+               }
+               if sourceVersion > targetVersion {
+                       suffixes, err := getVersionedBinarySuffixes(sourceBinary + "*")
+                       if err != nil {
+                               return fmt.Errorf("failed to get machine-config-daemon versioned binaries: %w", err)
+                       }
+                       suffix, exists := suffixes[targetVersion]
+                       if exists {
+                               sourceBinary += suffix
+                       }
+                       klog.Infof("container is rhel%d, target is rhel%d", sourceVersion, targetVersion)
                } else {
-                       klog.Infof("using appropriate binary for source=rhel-%s target=rhel-%s", sourceMajor, targetMajor)
+                       klog.Infof("using appropriate binary for source=rhel-%d target=rhel-%d", sourceVersion, targetVersion)
                }
+
        } else {
                klog.Info("assuming we can use container binary chroot() to host")
        }
-       sourceBinary := "/usr/bin/machine-config-daemon" + sourceBinarySuffix
+
        src, err := os.Open(sourceBinary)
        if err != nil {
                return fmt.Errorf("opening %s: %w", sourceBinary, err)
@@ -596,6 +612,33 @@ func ReexecuteForTargetRoot(target string) error {
        return syscall.Exec(targetBin, newArgv, newEnv)
 }
 
+var regexDigits = regexp.MustCompile(`(\d)*$`)
+
+func getVersionedBinarySuffixes(basePath string) (map[int]string, error) {
+       result := map[int]string{}
+       matches, err := filepath.Glob(basePath)
+       if err != nil {
+               return nil, err
+       }
+       for _, match := range matches {
+               extension := filepath.Ext(match)
+               if extension != "" {
+                       versionBytes := regexDigits.Find([]byte(extension))
+                       if versionBytes == nil {
+                               // Skip, is a binary that doesn't have the pattern we are looking for
+                               continue
+                       }
+
+                       version, err := strconv.Atoi(string(versionBytes))
+                       if err != nil {
+                               return nil, err
+                       }
+                       result[version] = extension
+               }
+       }
+       return result, nil
+}
+
 // worker runs a worker thread that just dequeues items, processes them, and marks them done.
 // It enforces that the syncHandler is never invoked concurrently with the same key.
 func (dn *Daemon) worker() {

sourceBinarySuffix = ".rhel8"
klog.Info("container is rhel9, target is rhel8")
} else {
default:
klog.Infof("using appropriate binary for source=rhel-%s target=rhel-%s", sourceMajor, targetMajor)
}
} else {
Expand Down
2 changes: 1 addition & 1 deletion pkg/daemon/update.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2288,7 +2288,7 @@ func (dn *Daemon) updateKubeConfigPermission() error {
// (/home/core/.ssh/authorized_keys.d/ignition) or the old SSH key path
// (/home/core/.ssh/authorized_keys)
func (dn *Daemon) useNewSSHKeyPath() bool {
return dn.os.IsEL9() || dn.os.IsFCOS() || dn.os.IsSCOS()
return dn.os.IsEL9() || dn.os.IsEL10() || dn.os.IsFCOS() || dn.os.IsSCOS()
}

// Update a given PasswdUser's SSHKey
Expand Down